Orchard pest control

Deakin University is not endorsed by or affiliated by the Shell Company of Australia

Efficient pest control is essential for successful fruit growing. It can only be achieved by the use of first quality sprays, applied with a thorough understanding of their properties, and of the nature and habits of the various orchard pests.

This book has been drawn from a wide selection of Australian and overseas material, in an attempt to put the elements of pest control in a concise, readable form; it is based on a long experience of spraying oil manufacture, and a study of Australian conditions extending over many years.

Technical officers of the Shell Company are at all times ready to advise and assist on pest control problems, and it is hoped that this book will prove a valuable extension of Shell service to Australian growers.

We acknowledge with thanks the ready co-operation and assistance of State Departments of Agriculture throughout Australia 8

In this colour supplement illustrations of common orchard pests have been grouped together for easy reference and identification. More detailed descriptions of the life histories of these pests and of the control measures recommended for them will be found set out in Section Eleven.

Adult forms are shown above. Immature stages of this pest are similar in form, except that the wing cases may not be fully developed. In colour, the red is less pronounced, and they are largely black with some white markings.

The green abdomen can be clearly seen in the underneath view at right; a specimen turned into this position would also show the long black sucking beak or rostrum carried along the abdomen.

At lower left is the wingless adult, which emerges from the roots in early winter to feed mainly in the twigs (the green aphid favours the leaves.)

After several generations, winged forms as shown at right, appear, and these migrate to other trees, spreading the attack.

A typical infestation, a few generations old, is pictured in the general view at left.

The ‘H’ marking on the adult black specimens is typical. The light brown scale is an immature form. These may often be green.

A small black and brown insect, about i inch long when fully grown, this pest is often mistakenly reported as a fly, but it is a true sucking bug. The stings on the fruit are typical of the damage caused.

6- —Portion of apple branch, showing the effect of Red Spider on leaves. Natural size.

The extremely long front legs of this mite distinguish it from all other orchard mites.

The yellow and black markings on the adult often show variation; the life stages follow, fairly closely, those of the Codling Moth.

The larvae shun the visible surfaces of the fruit, preferring to feed and enter from the centre of a cluster of apples.

The main illustration shows a relatively light infestation of white louse. In heavy infestations, it will move even on to the fiuit. At lowei left is an immature male, the adult male being winged. At lower right is an adult female. Heavy infestations result in severe bark injury causing cracking and gumming.

The black rough lesions of this disease can be seen on both fruit and leaves the illustration. Fruits may become distorted as shown at lower right.

On the leaves the spots aie always brown in colour, sunken and small, being about 1/16th inch in diameter. On the fruit the first symptoms are small rust red depressions. These may develop into small sub-circular spots, brown and sunken in the centre with a darker raised margin, or they may develop into a large light-brown irregular sunken area, involving as much as half the fruit surface.

Excess showing yellowing at the tips and margins. Deficiency showing corking and splitting of fruit and main veins.

The illustration shows the typical yellow mottling of the intervenal regions, which on citrus has given rise to the name of “mottle leaf for zinc deficiency. On deciduous fruits, it produces stunting of the terminal leaves —hence the name “little leaf’’.

The commercial orchard is a storehouse of nourishment for pests of all types. Improved fertilizers and cultural treatments increase the production of fruit, but at the same time may also increase the potential food supply for pests.

Many of these insect menaces are kept in check by parasites and natural enemies such as birds, but often the orchardist must use chemical weapons, i.e., insecticides.

To choose the type and time of spray it is necessary to know the insect's characteristics and life history, and also the effect of the insecticide on the pest and on the tree.

Insects attacking orchards can be divided into two main classes based on the type of mouthparts and methods of feeding. The first class consists of biting and chewing insects such as codling moth, the pear and cherry slug, and various beetles, borers and grubs. The second class has long slender beaks or mouths adapted to piercing and sucking; the plant juices are drawn up from beneath the surface of fruit, bark or foliage. Scale insects, aphids, plant bugs, etc., come into this class.

It is obvious that when the leaves or fruit of the host plant are covered with a film of chemical which is poisonous if eaten, chewing insects will be killed, but sucking insects will be unaffected because they are feeding in a zone beneath the surface.

insecticide which will kill them when applied externally. Hence there are two main types of insecticides—

Where the mature insects are difficult to control because of their brief life or habits, an insecticide may be directed against one vulnerable stage in the life cycle, e.g., many of the pests which lay their eggs on the surface of leaves or fruit are readily controlled by ovicides—a special form of contact spray which kills their eggs.

The adult fruit fly presents yet another problem. It does not feed freely on the fruit it attacks, but lays its eggs beneath the surface; the maggots which hatch also feed beneath the surface. Consequently the only way to protect the fruit is to attack the adult by offering a poison bait spray, containing an attractant and a stomach poison.

Further distinctions may be made for the sake of convenience; they are useful attempts to classify insecticides in such a way that the orchardist will realise why some are used for specific purposes and are relatively useless for others. A knowledge of the materials used, and of the reasons why a definite time and method of application is recommended, will result in improved pest control and an increased yield of fruit.

Lead Arsenate—widely used and perhaps the safest arsenical to use on foliage. There are many compounds, which vary slightly in properties and in the ratio of lead to arsenate. The common lead arsenate is really “Acid lead arsenate”. There is another compound “Basic lead arsenate” which is not used in Australia, but in certain other areas where conditions render the acid form unsafe.

Calcium Arsenate and similar arsenicals are used widely in baits and also as sprays, particularly on cotton crops overseas.

Tartar Emetic and Fluosilicates—most commonly used in bait sprays for flying insects.

Plant derivatives—nicotine, pyrethrum, derris root, etc. These insecticides are usually very rapid in action and produce almost immediate symptoms, but in most cases their effect is short lived and they possess almost no residual action.

Sulphur compounds. Lime sulphur is widely used in many orchards. Various chemical forms such as colloidal, atomic and wettable sulphur are also used, particularly against mites. Sulphur compounds are perhaps most effective against young or newly hatched insects.

Mineral oils. These are widely used as scalicides and ovicides, as well as being fatal to many adult insects such as aphids and leaf hoppers. A fuller discussion of the important properties and differences between various petroleum oil emulsions is given later.

Complex organic compounds. Recently several complex materials have been developed as most effective insecticides. D.D.T. (dichlor-diphenyl trichlorethane) and Gam-mexane (hexachlorocyclohexane) are typical examples. The precise uses and limitations of these insecticides have not yet been fully determined, but they offer a new combination of qualities which should be most helpful to the orchardist. They possess high contact effect plus a residual action which was previously obtainable only with the more stable stomach poisons.

Fumigants. A number of fumigants has been used for controlling insect pests, but Hydrocyanic acid gas (usually from Cyanogas) and carbon bisulphide are the two most common in orchards. Hydrocyanic acid gas is usually used on whole trees under tents, while carbon bisulphide has been used in tunnels of borers and as a soil fumigant. Both are extremely dangerous gases.

The fungi are a large self-contained group of the plant kingdom. The characteristic which distinguishes them from the higher plants is that they are not divided into root, stem and leaf.

The body (thallus) of the fungus varies in shape and structure, but consists of some form of web (mycelium) composed of many interlacing strands (hyphae).

These strands give rise to fruiting bodies, and produce the spores which disseminate and continue the species. The fruiting bodies are often microscopic, but sometimes, as in the common mushroom, they are much more noticeable than the web of tissue from which they originate.

Fungi possess no chlorophyll (the green matter in leaves, which builds up food from carbon dioxide in the air) ; consequently they cannot manufacture their own food from simple materials and must derive nourishment from either living or dead plants or animals.

Only those which feed on living plants and animals are true parasites; those which feed on dead organic remains are known as saprophytes.

The distinction is not very clear, however, since many fungi which normally live as saprophytes on dead tissue may in special circumstances become parasitic on a living host. For example, when the roots of a plant are unhealthy, due to water-

logging, they may be attacked by a variety of fungi which are normally present in the soil and have no effect on healthy roots.

Ectophytes such as powdery mildew develop on the outside of the plant tissue and obtain nourishment by sending rootlike strands down into the plant. Since the body of the fungus is external, they can be treated with a fungicide after infection takes place.

Endophytes such as peach leaf curl develop throughout the actual plant tissues, and only small portions or none at all of the fungus may be exposed at the surface of the plant. Consequently they cannot be killed after infection develops, without killing the whole plant tissue. These fungi are dealt with by preventive measures, such as orchard hygiene and protective sprays applied before and during the times when fungus infection may be expected.

Just as two main types of insecticides have been developed, one of which is direct in action, while the other is protective, so these two types of fungi have led to the development of two main types of fungicide.

Against the ectophytes or surface growers, direct action fungicides are used. Sulphur compounds are typical of this type of fungicide, although they do possess some residual or protective value.

For a crop which can be expected to suffer from endophyte infection, protection can best be afforded by placing a thin layer of fungicide over all the susceptible tissues, so that any parasitic spore falling on the tissues is destroyed before it can obtain a foothold. The most satisfactory protective fungicides for most purposes in the orchard are the copper fungicides.

Sulphur compounds: The most commonly used sulphur fungicide in Australian orchards is lime sulphur, which is widely used on both pome and stone fruits. Late in the season when other forms are more liable to cause injury, finely divided sulphurs under various designations are also widely used.

Bordeaux mixture. This well known fungicide is prepared from copper sulphate (bluestone) and lime. The standard formula (6:6:40) requires six pounds of copper sulphate, and six pounds of hydrated lime or four pounds of quicklime, to forty gallons of water. These quantities are often varied and more dilute mixtures are recommended for specific diseases. In this mixture the copper has been precipitated until none remains in solution. The spray is therefore non-injurious on plants, and resists washing by rain. Most fungus spores secrete small quantities of acid when germinating, and this liberates sufficient soluble copper compounds to destroy the fungus spore.

Burgundy mixture is similar to Bordeaux, although less well known. It is prepared by using washing soda instead of lime.

Copper oxychloride—another copper compound, which has strong fungicidal powers. It has the advantage of being available in a form ready for immediate use.

Copper oxide or Colloidal copper. This has also been used in Australia, particularly on tobacco and citrus, but is not so well known as the compounds mentioned above. It is prepared by mixing solutions A and B below.

When used at the rate of three gallons of the mixed stock to forty gallons of water, it is as effective as 3:3:40

Oil emulsions are frequently used with great advantage in combination with copper fungicides. The presence of the oil emulsion improves the spreading and adhesion of the fungicide, giving better results. It also lubricates the spray pump, while the harsh mixtures such as Bordeaux are passing through.

In addition, it has a softening effect on the bark of the tree, which tends to harden with age and frequent applications of harsh spray. One quart of oil emulsion in one hundred gallons of spray is beneficial for these reasons, but frequently greater quantities are used in order to give control of insect pests such as red spider and scale.

Many other sprays as well as insecticides and fungicides may be used in the orchard. Attempts have been made to destroy fungus infections before they reach the plant by spraying the dead leaves where they lie with a fertilizer. This promotes rapid rotting before the fungi in the leaves can mature and discharge spores. Other sprays may be applied for a direct manurial value to remedy soil deficiencies or for physiological effects, e.g., hormone sprays. Sometimes sprays have even been used for destructive purposes, to regulate fruiting or to kill weeds.

Manurial Sprays. Zinc deficiency (see plate, page 27) is probably the best known example of a condition which calls for a manurial spray. A lack of this element in the

soil leads to definite leaf symptoms which can be recognised—mottle leaf on citrus, and little leaf on apples. The response to sprays containing zinc is much more rapid and certain than to additions of zinc to the soil. Often these symptoms appear when there are adequate amounts of zinc present in the soil, but in an unavailable form; or where zinc compounds added to the soil are quickly rendered unavailable by other compounds present. Both zinc oxide and zinc sulphate are suitable for spraying against this condition, but if zinc sulphate is used, it must be combined with lime.

Either zinc spray can be combined with Shell White-spray to incorporate a treatment for scale with the manurial spray.

Boron deficiency (see plate, page 26) is also well known, giving rise to a condition in the fruit, particularly of apples, which is known as “internal cork”. Boron deficiency symptoms are not always as clear cut as those of zinc deficiency,, nor is the response always as certain, but applications of borax as a spray, or to the soil, have led to satisfactory recovery in many cases.

Boron excess (see plate, page 26) has also been noted in citrus. It causes yellowing at the tips and margins of the leaves, which later spreads to the tissue between the veins. The tips and sometimes isolated areas along the leaf margin eventually die. Circular resinous spots often develop on the under leaf surface. Lemon and grapefruit are more readily affected than orange.

Since the trouble is largely due to excess boron in irrigation water accumulating in soil and trees, curative treatment consists of using water containing less boron (if this is possible) and good drainage, to reduce the boron concentration below a toxic level.

Copper deficiency, which gives wither-tip symptoms, can also be treated by spray applications containing copper, but this condition is rare, since most fruit trees receive copper sprays at some time.

Manganese deficiency has been recorded in Australian citrus, but is corrected by a spray of manganese sulphate and lime.

Magnesium deficiency is not uncommon, particularly on citrus. This deficiency is usually treated by soil amendment methods, consisting of the application of dolomitic limestone where soils are acidic, or magnesium sulphate (Epsom salts) where soils are alkaline. Under certain circumstances a spray of Epsom salts and lime, applied direct to the tree, may be necessary.

The best example of a spray applied to fruit trees, to produce a physiological effect is the hormone spray.

Hormone or cling sprays have come into great prominence in recent years as a means of preventing the preharvest drop of apples and pears. These fruits, if left on the tree, normally develop an abscission layer in the stem, which permits the fruit to drop. Unfortunately, this may start to develop prematurely, leading to the serious drop of fruit, just prior to normal picking time. This layer only develops when the supply of a chemical messenger in the sap begins to fall. It has been found that alpha-naphthalene acetic acid will serve as the chemical messenger, and if sprayed on the fruit stems, will be absorbed and prevent the abscission layer. It must be remembered, however, that the maturity of the apple is not delayed, and the fact that the fruit will not be lost as windfalls should not persuade the grower that it can be left on the tree after the recommended stage of maturity is reached.

Blossoming. Petroleum oil sprays have been frequently used as a control for thrips, not by spraying the insects, but as a dormant treatment for apples, in order to speed up the break of dormancy of certain varieties, so that they blossom before the thrips are present in sufficient numbers to cause serious injury.- In some countries, notably South Africa, this hastening of blossoming by means of a dormant oil spray has been used to obtain interpollination between varieties of apples which normally blossom at different intervals.

The spray outfit, either hand operated or power driven, has proved an economical and efficient method of applying weedkillers. These sprays have in the past been confined largely to the destruction of noxious weeds, but weedkillers have been recently used in U.S.A. to replace cultivation in irrigated orchards. The primary purpose of this operation has been to eliminate weed competition with the fruit trees, while preserving a desirable soil structure. The soil structure has a very important bearing on fertility and on the penetration of irrigation water. Continuous clean cultivation may impair the soil structure; but none the less weeds compete with the fruit trees for food and water, and so must be kept down. Weed spraying answers both these requirements; the power required to spray is much less than that required for cultivation, hence spraying is preferable on economic grounds also.

Certain varieties of fruits, particularly the Delicious apple, have a tendency to bear good crops only in alternate years. For other reasons, also, involving individual management problems, or market conditions, it may be desirable to destroy the blossom, thus saving the additional expense of spraying an unwanted or unmanageable crop through the whole season.

Several materials are available which will achieve the purpose by spraying without the slow and costly process of hand picking. Among other materials, oil emulsions containing dinitrocresol, normally applied as dormant sprays, have been satisfactorily used for destroying the blossom.

All petroleum oils, whether used for lubricating or for pest control purposes, are composed of a large number of compounds, which are related to each other chemically, but may exhibit very different properties.

It is for this reason that we can never speak of oils having a boiling point, as we do of water and other pure compounds. Rather do we speak of the boiling range of an oil, and this term indicates the range of different compounds present in an oil, since a pure compound always boils at the same temperature under constant conditions.

Hence we see that just as a crude oil contains various fractions such as petrol, kerosine, lubricating oil, bitumen and waxes, so a commercial spraying oil consists of various compounds, some more volatile than others, some more reactive than others, some heavier than others, etc.

Because oils consist of complex mixtures of compounds, it is impossible to obtain the precise compound required by naming it as we can name nicotine sulphate, copper sulphate and other single compounds.

A series of specifications can, however, ensure that no undesirable compounds are present in the mixture which makes up the oil we wish to use.

For example, a specified boiling range will ensure that oil fractions which are too volatile, or not

volatile enough, are absent. Similarly, a specification of colour in oils used on textiles, will ensure that no compounds likely to stain the fabrics, are present.

It is obvious that if the orchardist is to obtain the maximum benefit from the use of spraying oils, it will be necessary for these oils to be carefully chosen, so that they conform to recognised standards of purity, stability, viscosity and volatility, as embodied in standard specifications.

The more important properties with which the orchardist may be concerned, because of their bearing on the performance of spraying oils, are discussed in some detail below.

The specific gravity of an oil is of no direct importance to the performance of the oil as an insecticide, but it is usually included in a specification because it may give a valuable indication of the chemical nature of the components of the oil, since oils of different types may differ appreciably in specific gravity.

The viscosity of an oil is an expression of the rate at which it will flow, under standard conditions. This is obviously of great importance in the use of oils on fruit trees, to destroy insects. The rate of flow of a spraying oil must be such that it will readily spread over the body of the insect or egg and in the former case, it must also be able to penetrate the very small pores or spiracles through which the insect breathes. It must be capable of adhering for sufficient time to cause suffocation. On the other hand, leaves also have pores or stomata, through which essential gaseous exchanges take place, and the rate at which oils penetrate foliage, compared with the amount lost by evaporation and the reactivity of the oil when it has penetrated the leaf or fruit, determines the degree of safety in using the oil for spraying on foliage.

This property measures the tendency of an oil to evaporate, and is closely related to viscosity, out may in certain oils be quite appreciably different for oils of similar viscosity. This property also has a direct bearing on the efficiency of spraying oils. Oils of high volatility such as kerosine types, would soon evaporate from insects or eggs, with little effect.

On the other hand the use of oils with extremely low volatilities on plants in foliage may lead to an interference with normal leaf functions, which is undesirable.

Again it is necessary to select a suitable range of volatility within which a satisfactory spraying oil must fall. This range will of course differ according to whether the oil is to be used in Summer or Winter.

The measurement of volatility so that it can be related to field performance presents some difficulties. It is recognised that a dish of oil may lose only a negligible amount by evaporation, yet if that oil is spread as a thin film on blotting paper and exposed to the sun and wind, it may show considerable losses. Because of the difficulty of determining suitable conditions, the volatility of an oil is more often judged from records of distillation under standard conditions, since volatility is closely related to distillation results.

It is a known fact that certain compounds may be present in mineral oils, which are injurious to plant tissues, or which may, when spread out in the sun in thin films, oxidise to form injurious compounds. Weather conditions other than sun may affect this reaction. These injurious or potentially injurious compounds may be completely removed by refining treatment, and it is especially necessary in summer spraying to use an oil that will show a minimum tendency to oxidise when exposed for long periods at high summer temperatures.

During winter and early spring the danger and rapidity of oxidation is less severe, and less stringent specifications are required, thus permitting a lower cost of refining and a cheaper insecticide for the orchardist.

To some extent the lack of colour or “whiteness” of an oil may be taken as an indication of its purity. The change in colour, if any, on exposing the oil in a thin film to direct sunlight is also a useful indication, but these tests alone cannot be entirely relied upon.

However, the dangerous and potentially dangerous compounds which may be present in an oil almost invariably combine with sulphuric acid under certain test conditions, and the extent to which an oil will combine with strong sulphuric acid is a valuable guide to its safety on plant tissue, providing the viscosity and volatility are satisfactory.

The more acute type of injury known as “burn” can be eliminated by selecting oils which combine with sulphuric acid only to a very limited degree. The less obvious ill-effects which could result from extremely viscous and nonvolatile oils, even of high refinement, are avoided by selecting suitable specifications, as discussed above.

It has been established that oils which are otherwise eminently suited for use as spraying oils, may differ quite widely in toxicity or insect kill. It has not as yet been possible to link this property definitely with physical or chemical tests which can be rapidly carried out in the laboratory. The only final answer to this question is the kill of insects obtained by the oil. For this reason, the wise and prudent orchardist will use only those products which have been proved over the years. The record of Shell spraying oils is proof of their efficiency.

The use of petroleum oils for control of insect pests on plants goes back through the centuries to the time of the Greeks and before, although the foregoing relationships between properties of oils and their suitability as insecticides were not known. In Grecian times oils were applied undiluted by means of a feather. With the development of the spray machine for fruit trees, oils were at first of limited value, because no method was known of atomising oils to such a fine state of division that trees could be treated without placing an excessive amount of oil on the tree.

Within the last few years developments have taken place which suggest that oils may be used for pest control in future, at least in many cases in the form of aerosols or finely divided clouds of vapour, which are blown through the trees without the use of large quantities of water as a diluent.

These aerosols may be obtained by mechanical atomisation or by the use of highly volatile, so-called “propellant gases,” but their development requires more research and field experiment before they can be offered to the orchardist with safety.

In the meantime emulsions provide a means to distribute the required amount of oil evenly throughout the trees on which the pests are present.

For our purposes an emulsion may be considered as a mixture of two immiscible liquids such as oil and water, the one being distributed throughout the other in the form of fine droplets. Since oil is lighter than water, the droplets of oil will float on the top of an emulsion and coalesce unless they are continually and powerfully agitated, as in the tank-mix oil emulsions used sometimes in America for fruit tree spraying, or unless an emulsifier is present which will prevent the droplets from coalescing. .

There are two main troubles which may occur with emulsions, when used in orchards. The emulsion may “break," in which case free oil will float on the top of the vat. This may be due to a lack of sufficient emulsifier, or interaction of the emulsifier with minerals in the water or deposits in the spray vat, which inactivate it. Alternately the emulsion may “invert," in which case a greasy scum will float on the top of the water in the vat. A normal spray emulsion consists of droplets of oil dispersed in water. The presence of other compounds from the spray water, residues in the vat, or improper mixing and diluting of the emulsion may cause the structure to change to a system of droplets of water dispersed in the oil. When this happens, the addition of further water will not mix with the oil or external phase, nor can it reach the water dispersed through the oil and in consequence, the inverted emulsion of water in oil will float as a greasy scum on the remainder of the water. If allowed to stand over a period, this inverted emulsion will also show free oil separating out above the greasy scum.

The effect of either of these mishaps on spraying is the same, and in each case most of the trees sprayed from that vat will receive hardly any oil at all, while the last few trees will receive all the oil and will probably be injured by the excessive deposit. Consequently, oil emulsions should be inspected from time to time during spraying and if there is separation of free oil or greasy scum, no further spraying should take place until the advice of some one trained in emulsions has been obtained.

Considering each of these properties in turn, it is obvious that for use in orchards by a wide range of individuals, any spraying oil emulsion must not be affected by transport or storage, and be capable of preparation for use by simple means. It must also remain stable in the spray vat, so that a constant quality spray with the same concentration of insecticide is drawn off by the spray pump.

The question of “quick breaking" may not be understood so easily. Everyone who has sprayed knows that a considerable amount of spray runs off the tree, and is lost on the ground. It is not so apparent, that oil emulsions, while running off the tree, may deposit some of their oil content in

passing, and that the emulsion lost to the ground may contain little oil. On the other hand, it has been shown that run off from some types of oil emulsion is actually richer in oil than the original emulsion. This is due to the action of the emulsion running off, which picks up oil deposited during the period of spraying prior to run off.

From this it follows that spraying the same amount of different oil emulsions at the same oil concentration, may result in widely differing amounts of oil actually being left behind on the tree. This has been demonstrated and proved frequently. It has also been shown that the deposit of oil on the tree is linked with the stability of the emulsion, and that the more unstable the emulsion the greater the deposit of oil. This gives us two contradictory requirements. Firstly the emulsion must be stable in the spray vat to prevent separation of oil, but secondly it must be as unstable as possible to give the maximum deposit of oil on the tree.

With the old type of soap emulsifiers, the only solution was to balance the amount of emulsifier as carefully as possible, in order to produce emulsions with the minimum stability which was safe in the vat.

A new type of emulsifier however is a great improvement. It has been found that this type of emulsifier gives stable emulsions when diluted with water in the spray vat, but

when the emulsion is divided into very small droplets at the spray nozzle, the emulsifier no longer prevents the coalescence of oil droplets. Consequently the emulsion becomes unstable and commences to “break” while the ₍Spray is driving towards the tree. This is the basis of the “quick breaking” type spraying oil emulsions, which may best be exemplified by the various pre-emulsified or mayonnaise type Shell spraying oils—Whitespray, Shellicide “D” and Pale-spray.

breaking emulsions have been developed, and these most recent types again place the accent on quick breaking properties,

It can be seen from this simple discussion of certain major factors involved, that the mere percentage of mineral oil in a spraying oil is insufficient grounds on which to judge an oil. Both the nature and the amount of emulsifiers present, the compatibility of the emulsifier with hard water and other spray materials, as well as the oil itself, all contribute towards the effectiveness of the spray.

The different requirements of basic oils and the differences in emulsion systems make it impossible for any one product to satisfy all the demands which are made on spraying oils. For this reason a variety of Shell spraying oils is available, and from these, an oil can be selected which is suitable for the purpose at the lowest price. A detailed discussion of the properties and purpose of each Shell Spraying Oil is given below to guide the fruitgrower in selecting the best spraying oil for any particular job. Representatives of The Shell Company will be most willing to expand these details and advise on precise recommendations at any time.

This product is primarily a foliage or summer spraying oil. The specifications for such an oil are much more exacting than those for spraying oils which are not used on foliage. The basic oil must be carefully selected so that volatility and viscosity are balanced to give a sufficiently stable oil film on the foliage without interfering with transpiration and respiration. Most important of all however, is the purity and stability of the basic oil, since certain fractions of crude petroleum and oxidation products of other fractions, may cause injury to fruit or foliage in mid-summer.

In order to produce this bland non-injurious basic oil, a great deal of refining must be carried out, using both physical methods such as distillation

and solvent extraction and chemical acid treatment to remove the reactive constituents. Despite this severe treatment, it has been found possible to retain in the oil, the highest degree of insecticidal and ovicidal efficiency. It has been commonly thought by many orchardists, that the fractions of petroleum oil which are most injurious to plants, must also be most injurious to insects. In other words, that the heavier the oil, the better it is, while highly refined oils have lost a great deal of their toxicity to insects. This is not so, and on the contrary, there exists very strong evidence for believing that within any given viscosity and volatility range, the more highly refined oils are more toxic to insects.

Shell Whitespray is one of the “quick breaking'’ emulsions, which when sprayed upon the tree gives a maximum deposit of oil on the foliage and fruit, while a minimum quantity is lost in the runoff.

This “quick breaking” emulsion is recommended for summer treatment of scale insects of all kinds, codling moth, red spider, bryobia mite and various aphids. It is unaffected by hard water and will mix readily and safely with both nicotine sulphate and lead arsenate; and it has been amply demonstrated that the use of Whitespray in conjunction with either of these materials increases their effectiveness. Whitespray should not be combined with lime sulphur or other sulphur compounds, nor should it be used on trees during the foliage period within two to three weeks of a sulphur treatment.

The method of mixing Whitespray for spraying must be carefully followed if the best results are to be obtained. The basic oil in Whitespray is already emulsified, but if water is added carelessly, or too rapidly, it may thin down unevenly to give small lumps which are very difficult to disperse.

The recommended method of dilution is to take one part of water and add to this ten parts of Whitespray.

is added. Then add one more part of water and again stir into a smooth cream. Water can now be added continuously with vigorous stirring, until the Whitespray has been diluted with an equal volume of water. At this stage the primary

There is a very great amount of spraying performed during the semi-dormant stage of growth of deciduous fruits. A high proportion of this spraying consists of fungicidal applications, but many growers apply oil sprays at this stage for the control of insect pests, such as red mite. The period described as semi-dormant in this book, is the time from early green tip stage in apples and pears, or bud opening in stone fruits, up to the pink stage just prior to the opening of the actual blossoms.

There may be several reasons for applying oil sprays during this period. In some cases continuous wet weather or machinery breakdown may prevent a dormant spraying and the use of Shellicide “D” at the semi-dormant stage may still prevent insect pests from running riot. Other growers prefer a semi-dormant spraying oil, since they consider the pests are more susceptible in early Spring than in the dormant season. Still other orchardists combine the oil spraying with a fungicide. Both these necessary treatments are then applied simultaneously, thus saving one spraying.

Shellicide ”D” is a prepared emulsion similar to White-spray, except for the basic oil, which is appreciably heavier and less volatile. The emulsion is unaffected by hard water and is specifically designed to combine with Bordeaux mixture and lime sulphur. Directions are given later for the detailed methods of preparing these combination sprays. For the present it can be pointed out that not only is it possible to combine oils with these fungicides, but the combination is definitely beneficial, since the Shellicide “D” acts both as a spreader and more particularly as a sticker, leading to more uniform and more permanent cover.

It should be noted here, that although Shellicide "D” combines with lime sulphur, with perfect safety up to the pink stage of development, the use of oil sprays with sulphur sprays may be dangerous later in the season, and should be avoided.

Shellicide “D” is a “quick breaking” emulsion of the same type as Whitespray. While possessing a high degree of purity and stability, the basic oil specifications are not as stringent as those of Whitespray and consequently Shellicide “D” is cheaper than Whitespray.

It is used at a period intermediate between dormant and foliage type sprays, and is truly intermediate in the character and nature of its basic oils between Whitespray and dormant oils. Directions for diluting and mixing Shellicide “D” are identical with those given for Whitespray.

Palespray is a pre-emulsified spraying oil of the “quick breaking" type, the emulsion system being similar to White-spray and Shellicide “D," but it embodies a dormant oil similar to that which has been used for so long in Redspray. It is unaffected by hard water and can be combined with lime sulphur or Bordeaux mixture.

Palespray is considered to be the most efficient dormant oil spray which is available. It retains the high quality basic oil which has proved its toxicity and efficiency for many years in Redspray. This basic oil is moreover incorporated in an emulsion which is suitable for all types of natural waters and maintains a high oil content with “quick breaking" characteristics to give a high oil deposit on the tree.

Palespray is replacing Redspray because as a more modern development, it will do everything that Redspray does and has additional advantages.

It must be remembered that Palespray is a true dormant oil, and should not be used after the break of dormancy.

In some cases lime sulphur and spraying oil give more efficient dormant or semi-dormant pest control than the use of either of these materials separately, and the combination of Palespray with lime sulphur as a dormant spray can be thoroughly recommended.

The method of mixing Palespray and diluting with water is identical with that given above for Whitespray. It is important that the initial dilution should be made very gradually, just as in the case of Whitespray.

This product has been on the market for a great many years, and has achieved a high reputation in all orchard districts of Australia and New Zealand, because of its consistent results. While it is believed that Palespray is even more efficient than Redspray, the latter is still marketed to meet the demands of those growers who have always used “red oil" and prefer to continue with it.

Redspray cannot be classed as a “quick breaking" type, nor can it be combined with lime sulphur or Bordeaux mixture. Difficulties of emulsification and stability may arise if the water available for spraying carries dissolved mineral salts.

With these limitations Redspray has given good service and general satisfaction over wide areas in Australia, and the consistent quality and basic oil specifications are being maintained.

This spray oil being a clear oil in appearance, is not a pre-emulsified type like those discussed above. Care is again essentia] in preparing a primary emulsion. Equal parts of Redspray and water (or slightly less water if difficulty is being experienced) are poured into a clean vessel and stirred vigorously until a creamy white emulsion is produced. This primary emulsion can then be added to the bulk of the water in the spray vat with the agitator operating.

This product resembles Redspray “A” in general properties, but has been modified so that it will emulsify with naturally hard water. It has only been possible to do this at the expense of the percentage of oil present and Redspray “C” contains appreciably less oil content than Palespray and cannot be expected to give comparable oil deposit on the tree.

Redspray “C” is renowned for its wetting and spreading properties and while these may not always be advantageous, if they result in too thin a film of insecticide, this product is of particular value when attacking a pest which is difficult to wet properly, such as woolly aphis.

The directions for mixing are identical with those for Redspray. A primary emulsion is prepared using equal parts of oil and water. This creamy white emulsion can be poured into the remainder of the water in the spray vat.

. Redspray heavy is a similar spraying oil to Redspray but incorporating a heavier oil of lower volatility. This product has proved very popular under Tasmanian conditions.

It cannot be relied upon to emulsify satisfactorily, if the water used is appreciably hard, and it cannot be safely combined with lime sulphur or Bordeaux mixture. Nevertheless, where it has been used as a straight dormant spray, it has given general satisfaction for the control of Red Mite eggs, scale insects and other pests present on pome trees during the dormant season.

Directions for mixing Redspray Heavy are identical with those already described for Redspray.

_# This product differs from all the other Shell spraying oils described above, in that the insecticidal properties of the basic mineral_ oil are increased by adding a potent organic insecticide—dinitrocresol.

T his poison increases the range of pests which can be killed and is primarily designed for control of the tough overwintering eggs of green peach aphid and black cherry aphid, with a simultaneous control of other pests linked with these on peaches and cherries, such as San Jose Scale and Red Mite. Dinitrocresol also has an appreciable effect on fungi, and except on susceptible varieties in years of severe infection, it will give protection against peach leaf curl disease. In the dessert peach areas, however, a fungicidal application is still recommended in addition to Universal Winterspray, since every year must be considered a potential year of severe infection with peach leaf curl, because it cannot be controlled once infection appears in the leaves.

While Universal Winterspray will control some pests of apples and pears, it is not recommended for this purpose, since at equivalent concentrations it is more expensive than straight spraying oils, which give equal performance. It is specially designed for use on peaches and cherries.

Universal Winterspray is a pre-emulsified type of spraying oil and can be combined with hard water without any ill-effects. It is designed for purely dormant use, and cannot be used after the buds commence to break dormancy, without risk of serious damage.

The method of mixing Universal Winterspray is identical with that used for Whitespray and described above. Be careful to add only approximately one-tenth water compared with the amount of oil, and stir this into a smooth cream before further dilution.

Shell Ditrene A is essentially a DDT concentrate in the form of an emulsion which is outstanding for the high DDT content achieved. The DDT present in this product represents at least 36% para-para isomer of DDT by weight/volume, i.e., 3.6 lbs. per gallon. The particle size of this DDT is carefully controlled to give fine uniform dispersions without any coarse aggregates which might settle in the vat or block spray nozzles.

I he product is so formulated that no compounds are included which are potentially dangerous to plants, such as the high aromatic solvents frequently used for DDT. The small amount of highly refined oil used, however, ensures that the deposit of DDT will adhere to the foliage, and not powder off, as might otherwise be the case. It is recognised that maximum effect can be achieved in this way, both in the adhesion of the deposit to the foliage, and in toxicity of the preparation to insects. Moreover, as a result of the ingredients being used, this material is safe to apply to foliage at any period of the year.

Shell Ditrene A may be used for the control of all orchard and vegetable pests which are known to be controlled by DDT, such as codling moth, Rutherglen bug, oriental peach moth, green and black peach aphids, canary fly or apple leaf hopper, apple root borer, pear and cherry slug, bronzy orange bug, Fuller’s rose weevil, cabbage caterpillar, bean fly and many other common pests.

At the time of writing, further investigations with DDT are being actively pursued against these and other pests. Hence this list is not exhaustive, and any complete list at this juncture would be incomplete in twelve months’ time. Nevertheless, it can be safely accepted that where DDT is known to control a pest, Shell Ditrene A will equal or surpass other DDT preparations.

Experience so far indicates that Shell Ditrene A will prove a valuable aid to growers when used as directed. It should not be combined with nicotine sprays, since there is evidence that the two materials are incompatible. The use of Shell Ditrene A in combination with White Oil emulsions has been satisfactory in all tests so far completed, but this combination should not be used except at the grower’s own responsibility, until further information is available.

DDT has already shown its usefulness in fields of agriculture other than horticulture, and Shell Ditrene A will be found to give excellent results when used for the control of flies and mosquitoes around dairies, stables, barns and other farm buildings. Specific instructions for these applications are given on the label. Other applications include spraying on cattle for the control of buffalo fly, and as a treatment for ticks, lice and fleas on farm animals.

Full mixing directions as given on the individual containers show that this product is notable for the ease with which it can be diluted for use. Before removing any concentrate, ^rol^ *-he. P^ackage and thoroughly stir the contents to ensure uniformity; then pour off the required amount of concentrate, and thin down by stirring in an equal quantity of water before adding to the spray vat.

For most horticultural pest control para-para DDT is used at the rate of 1 lb. per 100 gallons. To obtain this dilution Shell Ditrene A is used at 1 part in 360. This is equivalent to 45 fluid ounces or 2\ pints per 100 gallons. Double this concentration is used for a few pests, such as the larger horned citrus bug and the orange piercer moth. It is entirely probable that modifications of dosage will be made, as further experience in the use of DDT for pest control is accumulated.

Shellestone is a plant hormone spray for the control of preharvest drop of apples and pears. In addition to the main hormone constituent, alpha naphthalene acetic acid, this product contains wetting and spreading agents to assist in thorough coverage and produce the maximum effect from the hormone applied.

Shellestone mixes immediately with hard or soft water, and can be used by pouring directly into the spray vat with the agitators in operation.

The results obtained will depend on the thoroughness of application, and on the timing of the spray. It is essential to wet the fruit stalk and in order to achieve this, a driving spray under high pressure, should be used.

The spray does not become effective for 2-3 days, but then remains effective over a period of 2-3 weeks. Consequently the spray should be applied about twelve days before picking commences, and should the harvesting period be delayed more than a week, a further application should be given to provide protection against drop.

Shellestone, while preventing premature drop of fruit, will not delay maturity and the fruit should not be allowed to hang beyond normal maturity.

The combining of two or more spray materials is frequently very attractive for reasons of economy in labour or time. In general, it is advisable to keep the composition of sprays as simple as possible and avoid undue combinations, but occasions repeatedly arise where the spraying program is such that combination sprays may be economical, speedy and safe.

A revised compatibility chart is given in this book to enable growers to determine readily whether combinations which suggest themselves are in fact safe and desirable. ''Compatible may be used in several senses such as physical, chemical or biological. For example, tartar emetic and sugar are used as a poison bait spray for thrips. Oil sprays can be combined with this mixture without any chemical change or any damage to fruit or leaves, but if this is done the thrips just don’t feed on the mixture, so the combination is undesirable. Similarly Whitespray and lime sulphur will combine perfectly in the spray vat but if the combination is used on fruit or foliage, damage may result; obviously these materials are classed as incompatible. Yet again, Palespray and Redspray are compatible in a spray vat but there seems no reason why such a combination should ever be used. Hence the compatibility chart given here is restricted to those mixtures which are compatible in use, and spray materials may be shown as incompatible due to physical, chemical or biological

interactions. Because of the frequency with which they are used, specific details on the mixing of spraying oils with certain other materials are given here.

Only the pre-emulsified mayonnaise type of spraying oil should be used with Bordeaux mixture.

Prepare the Bordeaux mixture in the spray vat using about three-quarters of the total water. Make a primary emulsion by diluting the oil spray with equal parts of water, carefully following the directions given for the particular oil either on the label or in this book.

Add the creamy primary emulsion to the Bordeaux mixture in the spray vat with the agitator running, and make up to the total desired with the little water which may be required.

Make a primary dilution of the required amount of spray oil with an equal volume of water. With about three-quarters of the total water in the spray vat, add this primary emulsion with the agitators running. Then add the required amount of lime sulphur slowly with the agitators still running and finally top up with water to the required volume.

With solids such as lead arsenate, cryolite, zinc oxide, etc., it is desirable to disperse the solid in about three-quarters of the total water in the spray vat. The oil spray is then diluted with an equal volume of water according to directions and added to the suspension in the spray vat with the agitator running.

Such supplements as water conditioners, stabilizers, etc., should be added first of all to the spray vat if they are being used. Spreaders and stickers should be used according to individual directions on the container.

COM PAT I B! LIT Y CHART

Whilst the choice of the correct spray material and its proper application at the right time are the basic principles underlying efficient pest control, nevertheless a most important part is played by the spray equipment itself. Factors such as the capacity of the plant, the pressure at which it operates during prolonged spraying periods, its mobility and reliability can make or mar the efficiency of any spraying programme, and we therefore propose dealing in some detail with the more important points.

Many growers are giving serious thought to the installation of stationary equipment, because under their conditions this type appears to offer greater efficiency with lower operating costs. The advantages of stationary equipment are briefly as follows:

• Speedier spray application. With mobile equipment a considerable amount of '‘non-spraying" time occurs, because of time lost travelling to and from the water supply (probably 25% to 30%), and because under excessively wet conditions the equipment cannot travel in the orchard. More time is also spent on adjustments and repairs to mobile equipment, since it is exposed to weather, spray drift and jolting.

• Timeliness of sprays. The whole success of a season’s pest control programme may be endangered by the inability to move a mobile outfit in the orchard at some critical stage.

• Reduced running and labour costs. Stationary systems eliminate “non-spraying” time, while fuel costs are less than those required for a mobile plant when the latter is tractor-drawn. In one case well know^Tn to us, running costs were reduced from 3/4d. per 1,000 gallons to 1/lid. per 1,000 gallons. The saving of labour by a stationary system is furthermore important at a time when labour is difficult to obtain.

• Ease of application. Slopes and hillsides present little difficulty to stationary system, and there is no damage to cover crops as is the case with a mobile unit.

• Depreciation and repairs. These are materially less when the pump and engine are housed under permanent cover.

• Higher initial outlay. This may be an insuperable barrier in some cases, but particularly with apples and pears, where a large number of sprays is applied, the annual saving would soon offset the higher initial outlay. Perhaps with citrus and stone fruit where relatively few sprays are applied each year the cost may not be fully justified. In these cases, however, the economical factors associated with pest control in each individual orchard would need to be given careful consideration.

• Time wastage. Despite what has been written under advantages, exceptional circumstances can occur under which time is actually lost using a stationary system. Such may be the case when different varieties of trees requiring different treatment are scattered throughout the orchard.

• Loss of spray material. Some loss in the pipelines cannot be avoided, but the extent of this loss can be minimised by skilful management in the pumphouse.

The next question to be decided is the capacity required. For proper pest control it is absolutely essential that each variety of tree be covered as quickly as possible. The equipment, therefore, must be capable of handling the required sprays within a week at the outside, otherwise the pests at the bottom of the orchard will be having a grand time before you get around to them.

To arrive at the required capacity one must allow, firstly, for “non-spraying time’’ (which is in the region of 25-30% for mobile equipment), the likelihood of temporary delays such as adverse weather conditions, and the fact that most equipment manufacturers rate their capacity at maximum operating speed, whereas it is more economical from the viewpoint of fuel and maintenance costs to run the equipment at half speed or even less. All these factors must be carefully considered.

As a general rule, however, it can safely be said that for each acre which must be sprayed at a given time (this applying particularly to apples and pears) the equipment should have a capacity of about 8/20ths of a gallon per minute when operating at the economical half speed. This would mean that for a 20-acre orchard of apples and pears sufficient plant would be needed to apply 8 gallons per minute at half speed or 16 gallons per minute at full speed, if this is the basis of capacity rating used by the manufacturers.

In America equipment capable of giving an average of 600 lbs. sq. in. at the nozzle appears to be regarded as standard. In Australia there is a need for such high pressure for citrus spraying, to carry the spray through and over the foliage, but experience suggests, however, that a nozzle pressure of 400 lbs. sq. in. is all that is needed to give thorough coverage of deciduous trees.

The pressure at the nozzle should be identical when using mobile or stationary equipment, but stationary plant has the additional job of pumping the spray throughout the orchard. A pressure drop due to frictional losses in

the pipelines occurs, and, in addition, where spray has to be pumped uphill there is a further loss due to gravitational effects. Provided the layout is properly planned, however, the pressure lost due to these causes should not exceed 150 lbs. sq. in., but provision for this amount should be made: hence the stationary spray pump must be capable of producing a pressure for deciduous fruits of at least 550 lbs. sq. in., and for citrus of perhaps 650-700 lbs. sq. in.

All equipment should be fitted with a proper pressure regulator, so that when the rod or gun is shut off the surplus spray can return to the vat with the engine running at idling speed rather than under full load. One must ensure that the power unit is adequate, so that it does not have to be run at maximum speed to maintain the pressure and throughput needed.

As a guide the required horsepower has been calculated to be approximately 1 b.h.p. for each 10 gallons pump capacity at 100 lbs. sq. in. Thus, if you require 20 gallons per minute capacity at 500 lbs. sq. in. pressure you will re-

From time to time claims are made that rakes will simplify spraying operations and will give better pest control. Experience suggests, however, that when rakes are used one sweep covers such an area that the spray operator may be mistaken as to the thoroughness with which the spray has been applied. In this way the success of the whole season’s pest control may easily be jeopardised.

Rods and guns are both very efficient, but each has its place. In the case of calyx sprays on apples and pears it is important to fill the calyx cup and a spray rod, preferably with “Y” nozzles, should, in the interests of efficient pest control, be used for these sprays. Only by the use of a rod can you spray into those calyx cups which are pointing upwards. At a later stage when the fruit is tending to hang downwards and the thickening foliage might prevent the use of a spray rod inside the tree, a spray gun is quite effective. For big trees it should be remembered that somewhat higher pressure is needed with a spray gun so as to cover the entire tree.

Some spray materials form undesirable and dangerous combinations with others; consequently, every care must be taken to clean out the plant after each spray operation. This applies with equal or greater force to stationary equipment, in which partial or total blockage of piping may follow sedimentation or corrosion by spray materials left in the pipeline. The entire outfit should, therefore, be flushed out after each day’s spraying, and if the spray residues cannot be removed in this way more drastic cleaning methods, such as an alkaline cleaning agent for the spray vat, or dilute hydrochloric acid for the pipelines of stationary equipment should periodically be used.

The trouble-free running of the spray equipment is a first essential in any efficient pest control programme; consequently, the equipment should be thoroughly overhauled before the spraying season commences and, in addition, certain precautions should be taken during and between seasons so as to maintain the equipment in a first-class condition.

Grind in the valves and/or fit new piston rings if compression is not satisfactory.

Examine electrical equipment, particularly spark plugs, which should be cleaned, adjusted to correct gap or replaced if worn out.

The hose has to stand up to very high pressures and much of the material used in spraying deciduous trees is somewhat abrasive, consequently, the hose should be carefully examined, and mended if necessary so as to avoid bursting under operating conditions. The hose should always be flushed clean and stored in a cool, dry and dark place.

I he pump piping and hose must be thoroughly flushed of all sediment after each day’s work.

The spray pump must be housed under cover, particularly in areas subject to heavy frosts. The pump should be covered with bags and care taken in very cold weather when starting up. If there is any risk of the pump cylinders freezing up, hot water should be applied before starting.

As mentioned earlier the trend in America particularly has been to the use of high capacity, high pressure equipment, and, as a matter of interest, several units of this type are illustrated.

One important feature which applies particularly to citrus spraying is the use of towers, some fitted with catwalks, enabling the spray to be applied directly to the tops of the trees. As reinfestation by citrus Red Scale frequently starts from this point, the use of attachments of this kind to Australian equipment would undoubtedly pay handsome dividends in control of citrus pests. Towers are not so necessary where deciduous trees are sprayed with the use of rods, and may even be a nuisance in the orchard unless trees are widely spaced.

One very recent development is the use of large volume, low velocity mechanical sprayers, which rely on an air stream to carry the spray through and over trees. This type of

sprayer eliminates the hand application of sprays, and consequently cuts down labour costs to a very marked extent. It depends for its operation upon the draught created by a large fan blowing past a number of jets which deliver the spray.

The spray material is immediately atomised by the volume of air passing over it, and is carried through and over the trees by the air stream.

One unit, as illustrated, is stated to be capable of applying 15,000 gallons of spray in a 10-hour day. To maintain a high hourly output it is necessary for “non-spraying time” to be cut to a minimum, and this is achieved by the use of a tender which brings the spray material to the spray plant.

Although such equipment would obviously enable very rapid coverage of the orchard, it has not yet been adapted to a capacity suitable for individual small holdings. It is mainly suitable for contract spraying of deciduous fruits.

The theory underlying the design of smoke generators, used during the war for smoke screens, is being used in the development of insecticide dispensing equipment. Here an insecticide such as DDT is dissolved in a special oil and the oil solution generated in the form of fog, which rapidly penetrates the foliage. The particle size of the fog is such that the majority soon settles, binding the insecticide to the leaves, fruit, etc.

Surprisingly high kills of some insect pests have followed the use of this equipment, due largely to the penetrating power of the fog and the very fine state of division of the insecticide.

Insecticides of the mist type are being applied by aeroplanes and helicopters, and this type of application has already been used on a small scale in Australia for the control of Rutherglen bug and plague locusts.

These mist sprays are intermediate between fogs and ordinary sprays. Oils carrying toxicants are used at a low rate (5-15 gals./acre) without any dilution with water. They are widely used for vegetables and row crops, as well as orchards, in U.S.A.

Many points which appear on the surface to be of minor importance can play a significant part in the success or failure of the pest control programme. The following represent but a few factors contributing to success: —

Probably one of the weakest features of many pest control programmes is the fact that the men operating the spray gun are not always fully aware of the life cycle of the pest against which the spray is being applied. The education of these men so that they will realise what they are doing and the importance of each phase of pest control is a vital necessity in all orchards.

Proper spraying really starts with adequate pruning, for the former cannot be undertaken if the tree is full of unnecessary laterals and foliage which prevent proper manipulation of the spray rod or gun.

This point has been referred to before and cannot be over-emphasised. No spray programme can hope to be successful unless it is applied at the correct time. In the case of Red Scale control on citrus there is a somewhat greater margin for tolerance than in the case of Codling Moth control. In the latter case, however, the sprays must be applied at the correct time, and no amount of concentrated effort at a later stage will make up for earlier deficiency on this score.

One cannot repeat too frequently the need for thorough coverage of every part of the tree, and the 64

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extra time necessary to give a thorough coverage is well repaid in clean fruit. If the spray equipment has adequate capacity, thoroughness and timeliness can still run together, but there is no doubt that if the spraying is skimped so as to apply the spray within the shortest possible period, there can be only one result —inefficient pest control.

The amount of spray per tree varies considerably, but a rough guide for a spray applied during the growing period is approximately 1 gallon per case of fruit.

It is a fallacy to think that one must spray during showers or immediately afterwards so as not to lose time. Actually, the trees should never be sprayed when they are wet, as by so doing the moisture on the trees breaks down the concentration of the spray material and may, in other ways, interfere with the complete coverage of the tree. For complete pest control it is a sound and economical proposition to cease spraying until the trees are dry.

Whilst no known harm will occur to the tree as a result of spraying under frosty conditions, this should not be done for the reasons set out under (5) above, i.e., dilution of the spray material. In this case also trees should not be sprayed until they are dry.

Although most sprays can be applied under high temperature and high humidity conditions, it is usually desirable to cease spraying when the temperature is in excess of 100°F., as burning may occur. In the case of lime sulphur sprays high humidity seems to be more important than high temperature, and it is sometimes found that where high temperature and humidity in excess of 65% occur together damage may result which would not be the case with lower humidities.

8. Calyx sprays on apples and pears must be applied from all directions, particularly downwards, as it is essential to fill the calyx cups.

9. Downward spraying for the tops of citrus trees is also essential for Red Scale control. Usually the scale control is very effective to a height of 6-8 ft., but above this height the efficiency decreases unless the spray operator gets above his work. With large citrus trees towers are a necessity.

10. DDT preparations should not be applied during blossoming, as this material is deadly to bees, which are essential in the orchard for cross pollination.

Because some materials used as insecticides are toxic to humans as well as to insects the several Departments of Agriculture have introduced certain maximum tolerances for fruit offered for sale. The materials mainly concerned are arsenic, lead and DDT.

The maximum amount of arsenic expressed as arsenic trioxide is 1/100th grain per lb. of fruit.

By careful selection of the pest control programme it is frequently possible to keep the arsenical residues below the allowable limit without impairing the control of Codling Moth, but this is not always possible and, therefore, methods have been devised for removing the arsenic from the fruit.

These involve washing of the fruit either in specially designed washing machines or in open troughs with-a 3% solution of commercial hydrochloric acid (i.e., 3 gallons per 100 gallons of solution). With those fruits with open calyx tubes, such as Delicious, Five Crown and Cleopatra, immersion should not exceed 6", otherwise the acid will probably penetrate into the fruit. The fruit should be immersed for approximately 2-3 minutes, drained, rinsed in water, or with the open calyx type in lime water (made by adding 10 lbs. of slaked lime to 100 gallons of water) and finally douched in running water to remove final traces of acid.

by small additions of acid at intervals, and in the trough type the acid solution should be entirely replaced for every 1,000 cases washed.

Because of the action of the acid on metals, it is essential for metal to be absent from all contact with the solution. Lead Residues:

Lead residues which, of course, occur in conjunction with arsenic following the use of lead arsenate sprays, are also toxic to humans, the maximum allowed being 1 /7th grain per lb. of fruit.

In practice, it is found that if the arsenical residues are within the limits allowed, the lead residues are also within the allowable limits. Consequently, no method of removal other than that outlined under arsenical residues is necessary.

DDT residues cannot be identified by visual observation, but can be determined by chemical means. Consequently, those who use DDT should satisfy themselves that their marketed fruit does not carry more DDT than the allowable limit of 10 parts per million parts of fruit.

DDT can be removed by washing in an alkaline bath, such as sodium metasilicate, but American practice, which is soundly based, is to avoid spraying with DDT preparations within three weeks of harvesting.

In some States health regulations exist which impose a maximum for any poisonous material of 1/25th grain per lb. However, this relates more to vegetable production than to fruit growing.

The right spray at the right time will control the spread of insect pests and fungus diseases very effec tively, but lack of attention to general cleanliness in and around the orchard, packing sheds, etc., can soon undo all the good work. Orchard hygiene involves:

Codling moth grub harbours in loose bark, crevices in props, old fruit cases, etc., and suitable action must be taken to destroy it.

Bandaging is an important aid to spraying in the control of various fruit pests, particularly the Codling Moth grub. 'The cost is not excessive, and, if the bandages are cut from old wool packs, duck or felt, they will cost less than Id. each for material and labour in cutting them, while one man can bandage about 400 trees a day.

The following points concerning bandaging for Codling Moth need special attention:—

The material used must be of a fairly thick and close character such as the above: chaff bags are practically useless on account of the openness of the weave.

Examine every week—otherwise the bands will form ideal breeding grounds for grubs. Unless this condition is complied with, it is much better to have no bandages at all.

Bandaging may be supplemented by stuffing paper in the lower forks of the tree. Burn and renew the paper every week.

Scraping the trees; all rough bark must be thoroughly removed, otherwise half the efficacy of the band is lost.

The necessity for this practice is apparent when it is remembered that apple and pear trees close to the packing shed are more severely attacked by Codling grubs than those growing some distance away. The grubs are carried in the fruit to the shed where they pupate and later emerge as moths. Eggs are then laid on the nearest trees. The packing shed, therefore, should be kept thoroughly clean and free from debris of any kind. The provision of moth-proof flywire screens over doors and windows is the best method of preventing egress of emerging moths.

Before using new props they should be barked, otherwise the loose bark affords excellent shelter for Codling grubs. See that the props are carefully stacked away at the end of the season.

Care should be taken of fruit cases that are used in the orchard. At the close of the season these cases should not be dumped under trees. They become stained and broken, and harbour many pests if allowed to remain in the open. Arrange, if possible, to place them under suitable cover; always stack them so that air can circulate about them, and see that the bottom row does not rest directly on the ground. It is a good plan when stacking the old cases to separate the broken ones from the others. Reconditioning is then much easier and should be done some time previous to the commencement of the busy season. Dipping secondhand cases in a solution of Lime Sulphur, 1 in 100, or Copper Sulphate, 1 lb. in 10 gals.

water, will greatly lessen risk of transit rot and other fungus diseases; while steaming or dipping the cases in boiling water will have a similar effect and will destroy the Codling grubs.

All loose bark on apple and pear trees should be removed. If allowed to remain, it affords protection for the Codling grub, Red Mite, and, in some areas, Mussel Scale. The removal of such bark also makes spraying easier. It should be burned, together with prunings.

A not uncommon sight in many of the older orchards is the great number of trees requiring surgical attention. It is very necessary to devote attention to fractures and other tree wounds, because it is these parts which offer ideal conditions for the development of fungus diseases, and shelter insect pests. This subject of tree surgery is such an important one that a special chapter dealing with it has been included on page 123.

Underground drains are usually only installed at great cost, and therefore should receive constant attention to see that they serve their purpose. The outlets must be frequently inspected and cleared of weeds and rubbish. A covering of fine

galvanised wire or perforated zinc is also recommended as this prevents the entry of small animals. Some experienced or-chardists, when laying covered drains, leave the higher end open. The grower can then test for freedom from blockage by shouting down the opening to another man stationed at the outlet of the drain. Any block prevents the voice carrying through.

In most orchards the Spring cultivation is important for the purpose of killing weeds, etc. Leaves and other vegetation that are so buried no longer provide shelter for insects and fungi. Apart from this, there is a manurial value in the matter turned in.

The uncultivated squares and strips at the butts of trees should never be allowed to remain, as they harbour a great number of pests.

The destruction of all diseased fruit, windfalls, etc., is of the greatest importance. Most windfalls are affected with one insect or another and therefore should be gathered about every 48 hours during the growing season and destroyed by burning or some other equally effective means.

Most States have proclaimed certain pests under their respective Plant Diseases Acts. Amongst these are the Codling Moth, Red Scale on citrus, and Fruit Fly. Generally the onus is on the grower to take specified control measures, with which the local Fruit Inspector is familiar.

It is in the grower’s own interest to take the necessary action and such Acts are only needed to compel growers to take the necessary measures in very few instances.

It is also profitable to pick all infested fruit at least once per week and destroy. If diseased fruit is left on the trees then millions of spores of fungus diseases, such as Brown Rot, Brown Spot, etc., will be carried by the wind, birds, etc., and affect sound fruit. The larvae of Codling Moth and other insects will mature and propagate their kind, thus leading to further infestation and greater loss.

Lures in pome fruit orchards not only act as guides for spray applications, but can assist in the destruction of many pests. Refer to page 76 for details of lures.

A knowledge of the life cycle of a pest is essential, not only to select the appropriate spray but to apply it at the right time and to best effect. The Shell Spray Programme is given later in this book; meanwhile this section outlines the life history, feeding habits and control methods of the principal orchard pests in sufficient detail to provide a thorough background to the problems of spray application.

An insect on hatching from its egg may either be a wingless copy of its parents or may differ from them completely. Examples of the first group are the sucking bugs, known in their immature stages as nymphs. During their development they moult several times, the wings gradually developing as wing pads. With some exceptions nymphs usually feed on the same food as adult insects.

The other group of insects includes flies, moths and beetles which in their immature stages are known collectively as larvae. The larvae of flies are also called maggots; larvae of moths, caterpillars and beetles are called grubs. They differ considerably from their parents in habits, structure and food preferences, and it is not until they pupate that any trace of wings appears. The pupal stage is followed by the adult or winged stage.

The insect may often be a horticultural pest at only one stage in the life cycle—e.g., only the larvae of the Codling Moth are destructive.

Other insects may cause damage in both larval and adult stages—for instance the larvae of the Apple Root Borer tunnel in the roots of the apple, while the adult feeds on the foliage.

Again, some species attack a different host plant at each stage; while the sucking bugs remain active pests on the same host from time of hatching until death.

Knowledge of the life cycle of an insect pest is therefore of paramount importance in devising effective control measures.

The two main types of insect pests which are encountered are those which feed by chewing pieces of the food material, and the sucking insects, which pierce the tissue and suck out the plant juices.

The attack of chewing insects is usually easily recognized in that the plant is actually chewed away. In some cases the damage is very characteristic and the treatment can be specified without actually seeing the insect.

In general, control is exercised by coating the plant surface with an insoluble poison which is harmless to the plant and is eaten by the insect. Protection is established by maintaining this layer.

This pest is found on native acacias and on apples, attacking young healthy trees as well as those weakened by other causes.

The adult insects may be found feeding on the leaves through the spring and summer months. Eggs are laid on the leaves, a pair of leaves being gummed together to form a sack for their protection. The larvae, on hatching, work their way down to the soil and attack the larger roots, rapidly destroying their usefulness by tunnelling along the surface. When fully grown, the larvae enclose themselves in an earthen cell for the pupation period, emerging in the spring as adult insects. The adults leave the soil and crawl up the trunk of the tree in the spring and summer, when the eggs are laid on the leaves.

Where this pest has selected weakened trees for attack, treatment must include correction of original causes of weakness, i.e., by pruning, cultivation, manurial treatment, etc.

Control of the borer may be obtained by hand picking the adult insects and the collection of the egg sacks. A very heavy lead arsenate spray is sometimes employed early in the spring when the adult beetles are first noticed.

Despite the many years of control investigations carried out all over the world against the Codling Moth it still remains the principal pest of apples and pears. It attacks all pome fruits, and occasionally some of the stone fruits and the walnut. It is impossible to estimate with any accuracy the loss to the fruit growing industry caused by the Codling Moth, but it probably ranges from 2% to 20% of the apple crops in different districts according to the climatic and seasonal conditions. Extra costs are also entailed of course in the buying and application of sprays.

Western Australia alone has been kept free of codling moth. There the unremitting efforts of departmental officers and the close co-operation of growers have prevented the pest from establishing itself, though occasional isolated outbreaks have been known.

The damage is caused by the larvae attacking the fruit and feeding on it internally; they devour the seeds and core tissue and leave an unpleasant mass of excrement in their place. Apples affected early will fall prematurely; but fruit attacked at any stage is rendered unfit for marketing. In addition, the presence of “stings” may seriously lower the market value of the fruit. These are the marks left by grubs which are poisoned after the first few mouthfuls are taken.

During Winter the full grown larvae lie in tough silken cocoons located in crevices of the bark, in the soil at the foot of the tree, in packing sheds and old used cases. In Spring, the larvae turn into inactive brown pupae from which small grey brown moths with copper coloured patches on the tips of the forewings emerge, usually towards late October. After a few days of inactivity the females commence to lay eggs, usually at dusk on warm evenings. WTen the larvae hatch they may feed on the leaves, but in a few hours they crawl to the fruit and chew their way inside, often entering near the calyx. When growth is completed inside the fruit the

larvae burrow their way to the outside and seek a sheltered place in which to spin cocoons. Pupation takes place within the cocoon and the adult emerges later to continue the life cycle.

The life history of the Codling Moth, in so far as the number of broods and the time of emergence is concerned, varies throughout Australia—for example, Queensland and New South Wales have up to three broods a season, while in Tasmania there would appear to be only one, with sometimes a partial second.

Control measures against Codling Moth can be divided into three sections, all of which are complementary and necessary for adequate control. It is interesting to note how these are built around the life cycle of the moth.

Orchard hygiene: this involves the destruction of overwintering larvae by the removal of rubbish from packing sheds and orchard, the clearing up of old cases, and the scraping of old bark from the trees.

Bandaging: this makes use of the habit of larvae to seek sheltered places to spin their cocoons. Thick bag or chemically prepared bandages are placed around the trees and the cocoons spun in them are destroyed.

Spraying: satisfactory control of the moth depends on the application of all methods, but spraying is the most important.

Sprays are only effective at two stages of the life cycle— a white oil ovicide such as Shell Whitespray is effective against the eggs, and a constant cover of lead arsenate is maintained on the fruit to poison the young larvae as they attempt to enter.

To carry out this programme effectively a calyx spray and a number of cover sprays are necessary, the number varying according to district and season.

After the calyx spray, which must be applied before the calyx closes, so that a plug of lead arsenate is present in the calyx throughout the season, most effective results are obtained if the cover sprays are applied at times of maximum moth activity.

For this purpose the use of lures can be of inestimable value in deciding when to apply cover sprays and often enable the number of sprays to be reduced, without loss of effectiveness.

A wide mouthed jar containing a 10% cheap wine or molasses solution makes a satisfactory lure. Usually 10 to 20 per 100 trees are sufficient. These should be inspected twice a week and cleaned and refilled regularly. Sprays should be completed within about seven days after periods of maximum moth emergence.

Shell Ditrene ‘A' has given outstanding control of Codling Moth. However, where DDT has been used there has often been a very serious build up of Red Spider and Mite and Woolly Aphid. To combat this applications of Shell Whitespray should be made as required.

The Oriental Peach Moth has caused serious losses to the fruit industry during past years and has proved to be a most difficult pest to control in seasons favourable for its development. It has been discovered from a close study of this pest that neither the numbers present at the end of the previous season, nor even the rate of increase of the moth population during the season can be taken as an index of the damage that will occur to the fruit.

The larvae not only enter the fruit but also tunnel into the twigs and growing shoots. Infestations as high as 80% of a canning crop have been reported.

In peach orchards eggs are laid near the young shoots or fruit, usually on the undersurface of leaves or on smooth stems, but never on the fruit. The hatched larva seeks a suitable place to enter a twig or fruit, and after spinning a web about itself, tunnels into the tissue until its body is buried. Twigs are entered near the tip, often through a petiole. A larva has been found to attack as many as three shoots during its feeding period.

Penetration into the fruit is usually effected at the stem end and the larvae tunnel to the stone of the fruit. When fully grown the larva leaves its host and seeks a place to spin its cocoon. In the early and mid-season these are spun high in the trees, but the overwintering generation descend to the ground by a silken thread, or crawl down the tree and form their cocoons in the soil under rubbish, or under rough bark on the tree.

Because of the peculiar habits of both larvae and moths and the vigorous growth of peach trees, particularly under irrigation, the effectiveness of cover sprays is considerably shortened, and a satisfactory control of the Oriental Peach Moth by means of spraying has not been developed.

Such things as bandaging, spring cultivation, proper orchard sanitation and sterilization of fruit cases are all valuable aids in controlling the moth. The introduction of D.D.T. has given excellent control of this pest and seems likely to become a standard spray treatment for late varieties.

The Light Brown Apple Moth is a native pest which feeds on a wide range of native and cultivated trees, including citrus, pome, stone and vine fruits. The caterpillar of this moth is, in certain seasons, a most injurious pest of apples and vines. It is spasmodic however, the fluctuations being due to the two factors of weather conditions and parasitic control.

Eggs are laid on the leaves during November and December. These eggs, which are green in colour and almost flat, hatch in about ten days, and the minute caterpillars feed on the underside of the leaves. They construct silken tunnels alongside the veins and midribs under cover of which they feed. After about three weeks the caterpillars burrow into tender leaves and stick the two sides of a leaf or two leaves together. They feed under cover, irregular areas of tissue being removed. In January growing shoots begin to appear very ragged and curled leaves become abundant. In late January or February injury is caused to the fruit, ranging from small blemishes to extensive markings. When mature the caterpillars turn into pupae, remaining where they have been feeding; and in 2-3 weeks the second generation of moths emerge. Their eggs, also laid on the leaves, take longer to hatch as the weather is cooler. Caterpillars will be found while there are leaves on the tree, and when these fall they will feed on available weeds. Caterpillars which have reached a certain stage will survive over winter without feeding.

When the buds open in Spring the caterpillars climb the tree and feed on the lower leaves and blossom clusters. Development is completed by October and the moths emerge and lay their eggs in November and December.

On the apple, normal Codling Moth spraying will keep this pest in check, while on other trees a lead arsenate spray should be applied.

Bandaging is obviously useless against this pest as the cocoons are spun at the feeding sites.

Very little work has yet been done on control of this pest with DDT, and it is possible that DDT sprays will prove effective.

These two species of fruit fly are perhaps the worst orchard pests found in Australia. The difficulty of controlling fruit fly is due chiefly to the female fly of each species depositing her eggs beneath the skin of the fruit.

Two other factors in favour of the flies are the extremely large range of host plants which they attack and their rapid adaptability to the climate of a new district.

The damage due to these insects is caused in the larval or maggot stage. The larvae feed and tunnel throughout the fruit in all directions, not only destroying a lot of tissue, but causing the attacked fruit to rot, which renders it useless for marketing.

The life histories of the Mediterranean and Queensland Fruit Flies are practically identical, hence an outline of the life of the Mediterranean Fly will apply to both.

The female fly when ready for egg laying makes a puncture in the skin of a suitable fruit, and then deposits a number of eggs in the underlying tissue. These minute punctures can sometimes be seen, and discoloured spots may develop around them on oranges, pears and apples. In some fruits the puncture exudes a small quantity of gum.

The young creamy white maggots feed and burrow in the fruit tissue for about two weeks until fully grown, when they crawl from the infested fruit and work their way down into the ground to a depth of 2 or 3 inches, where they pupate. After a period in the pupal stage the adult fly emerges and forces its way up through the soil to the surface. After its wings harden it flies away. Mating occurs during the next 4 or 5 days and the female commences laying her eggs. From egg to adult takes from 4 to 5 weeks in summer, but much longer in cold weather.

Owing to the egg laying habits of these flies control is rather difficult; but in fruit fly areas there are certain control measures which are compulsory, including the use of foliage poison sprays, fruit fly traps, and the regular destruction of fallen and infested fruits.

All infested fruit must be removed from the trees, and all fallen fruit collected at intervals not exceeding three days. Destruction of this fruit may be carried out by boiling in water for 10 minutes, burning, or by its disposal in a pit with an insect proof cover, so that the adult flies do not escape to re-infest the orchard.

This spray is applied to patches of foliage at weekly intervals for at least five weeks prior to the maturing of the fruit. Splashing the fruit should be avoided.

One trap is required to every eight trees at least, and is hung about 5 or 6 ft. from the ground in a sheltered position. The traps should be cleaned out and the lure renewed at least once a week.

The sucking insects include some of the most serious tree pests. Some sucking insects always betray their presence by the black mass of sooty mould fungus on the host plant. This fungus grows on the honeydew excreted by some species; otherwise the damage might be hard to detect. With other species curling and distortion of the leaves, and destruction of the green leaf colour are noticed before the insect itself.

In some cases damage is so severe that the introduction of a toxin into the tree by the pest is suspected. Due to the feeding habit, control must be aimed at killing the insect. Contact insecticides such as nicotine sulphate and oil sprays are used, but it is difficult to obtain lasting protection except by eradication.

The Green Peach Aphid is one of the chief pests of peaches and nectarines in Australia. It is also commonly found on a wide variety of garden and crop plants during the summer months. The damage caused by this Aphid is well known and takes place during Spring and early Summer. Where the infestation is severe the blossoms shrivel and fail to set fruit, while the leaves become distorted, curl over, and thicken to enclose the mass of feeding insects. Where fruit does set its quality and size are affected; serious damage may also be caused to the fruiting wood, thus injuring the following season’s crop.

T he Green Peach Aphid passes through the Winter in the egg stage, the eggs being laid during May to July on peach and nectarine trees, behind buds on the laterals and in small cracks. These eggs commence hatching about the end of July or early August, giving rise to minute wingless, olive green aphids. When the buds burst the aphids commence feeding on the young tissues and begin to multiply very rapidly by producing living young for several generations. It is at this stage that all the injury is caused to the trees. These Spring generations are wingless, but in early Summer winged forms are produced and the aphids migrate from the trees to various plants and weeds on which they live throughout the Summer and Autumn. In late Autumn winged forms are produced which fly back to the peach trees. There the wingless egg laying females are produced, and after mating with winged males, lay their minute, black eggs to repeat the seasonal life cycle.

As can be seen from the account of the life history of this pest, the obvious method of control is the application of an ovicidal spray during the dormant season just after egg laying has ceased. This is now general practice, using Shell Winterspray, which consists of an oil base containing an organic toxicant.

If Winter spraying is neglected nicotine compounds may be used after growth commences, but it is difficult to obtain good control at this stage.

The Black Cherry Aphid is closely allied to the Green Peach Aphid. It attacks cherries mainly but has also been found on plums. The effect of this pest on cherry trees is much the same as the effect of the Green Peach Aphid on peach trees.

The life cycle of the Cherry Aphid is similar in general outline to that of the Green Peach Aphid, except in a few details. Overwintering eggs are laid about the bases of fruit and leaf buds during May and June, and commence hatching about mid-July into black wingless aphids. In addition, however, to overwintering in the egg stage, small colonies may be found on some of the trees producing living young throughout the Winter. The presence of these aphids is usually indicated by the premature growth of infested parts. It has also been suggested that while migration takes place to other plants in the Summer months in other parts of the world, it is probable that in Australia the aphids remain on the cherry trees throughout the whole year.

The same principles and methods of control are followed as for the Green Peach Aphid, using Shell Universal Winterspray or DDT sprays.

The black Peach Aphid is rather difficult to control but fortunately is not as widespread as the Green Peach Aphid. The main damage caused by this Aphid is to the young shoots and leaves, which become shrivelled, distorted and blackened with fumagine—a fungus which grows on the honeydew excreted by the aphids. When severe, infestations may completely arrest young growth and an almost total crop failure will result.

Unlike the two preceding Aphid species the Black Peach Aphid does not overwinter in the egg stage, but as an aphid on the roots of peach trees. In Winter root feeding wingless aphids emerge from the soil, ascend the tree and attack the young growth, particularly the buds. After a few generations of wingless insects winged forms are produced, which migrate to other trees and give rise to fresh generations of living young. This species is not known to lay eggs nor have any true sexual forms been observed. About November the aphids return to the roots of the tree.

Because of its entirely different life cycle, the use of dormant ovicides as for Green Peach Aphid is of no use against Black Peach Aphid. As there are at present no economic and effective means of killing the root feeding aphids, all that can be done is to watch for and destroy those ascending the tree in the early Spring, using a nicotine spray.

DDT sprays may now be used for the successful control of this pest, because its effect lasts over the period that the aphids ascend the tree.

Red Scale is present in all the main citrus growing districts and is the most injurious pest of citrus trees. The economic loss due to this insect is very considerable.

Red Scale infests all above ground parts of citrus trees, and by extracting the sap reduces them to a weakened condition, even causing the death of shoots and branches. It is also suggested that the insect introduces a toxin into the tree while feeding, so that even small numbers may weaken a tree. A more direct type of loss is caused by infestation of the fruit, which must be brushed and washed before sale. These processes injure the rind and facilitate the entry of moulds, thus destroying the keeping quality of the fruit. Its appearance and consequently its market value may also be affected.

Red Scale does not normally reproduce during the Winter, and established individuals either die or develop very slowly into adults which can reproduce in the following summer.

Female scales begin to produce living young about the middle of November to early December, and these larvae or “crawlers” move away from the mother scale, and search for a suitable place to settle.

Having found a suitable place to settle, usually within a few inches of the mother scale, the “crawler” inserts its sucking mouthparts into the plant tissue and commences to feed. Simultaneously it secretes cottony threads which ultimately form the wax covering. The insect increases in size and casts its skin during growth, the female twice and the male three times. Development to maturity is slow, females taking about 9 weeks in Summer and 20 weeks in Winter. The average time is about 13 weeks, the females being fertilized at about 8 weeks old and the young being produced about 5 weeks later. Male insects are fully developed, with wings, at about 8 weeks, and leave their scales to fertilize the females. Each female produces approximately 150 “crawlers”.

As favourable conditions for reproduction extend from about November to April a rapid increase in Red Scale population occurs during Summer.

Life history studies show that from November to May there may be two generations and a partial third.

Red Scale is in most areas the most difficult and expensive pest to control on citrus. It may be controlled by efficient spraying with Shell Whitespray, the best treatment being two Summer sprayings applied December to end of February. A single Summer spraying can also be effective if conditions are favourable.

It can also be controlled by fumigation with hydrocyanic acid gas, or by using a combination of the two methods, an application of Shell Whitespray being followed within a fortnight by fumigation.

Bordeaux mixture for the control of black spot may be combined with Whitespray, but where Bordeaux mixture is used, fumigation cannot be applied within 6 months.

The Brown Olive or Black Scale is widespread in Australia and is chiefly a pest of citrus. Although the scales may be found on the fruit, it is the leaves and twigs which are usually infested. The insect damages the tree by sucking the sap, but injury also results from the copious growth of sooty moulds on the honeydew excretions of the scales. This causes a smutting of the leaves and fruit and greatly reduces its market value.

Brown Olive Scale is larger than the Red Scale, is oval in shape and has a raised H marking on the back. The colour ranges from a light to a very dark brown.

The females begin to lay eggs about 8 to 10 months after hatching and may each lay between 1,500 to 2,000 eggs. After hatching, the young remain for a short period beneath the parent scale, and then crawl actively about before finally becoming fixed.

The females moult twice and reach maturity in about 3 months. The male passes through an additional stage— the pupal stage—and unlike the female, which remains fixed, emerges from the scale as a minute two-winged insect. As egg laying extends over several months all stages of the insect may be found at nearly any time.

If spraying is carried out when the young scales are appearing a satisfactory control can be obtained with Shell Whitespray. Once the scale has been killed the sooty moulds will disappear.

The San Jose Scale is an injurious pest of deciduous fruit trees throughout the world, and is present to varying degrees in a large number of the orchard districts in Australia where pome and stone fruits are grown.

It is not serious, however, unless proper control measures are neglected. It has a wide range of host plants including apples, pears, peaches, plum, apricots and cherries.

The scale occurs on the limbs, twigs and the fruit. Badly infested trees have a scurfy appearance due to overlapping scales and show a decrease in general vigour, and unless the scale is checked may eventually die. Infested young wood and fruit usually have a pink inflamed area around each scale.

The Winter is passed in an immature condition, the scales of the last generation gradually developing to reach maturity by the following Spring. In the Spring the males emerge from the scale and mate with the females. The females continue to grow and produce living young which may number several hundred.

The young leave the mother scale, find a spot to settle down, insert their mouthparts into the plant tissue and commence sucking the sap. They gradually become covered with waxy threads and eventually the protective scale is produced. The young insects moult in a fortnight and then lose their legs. The males undergo two more moults and then emerge as two-winged insects. The females moult a second time and remain wingless, legless insects. They mate with the males and commence producing living young. There are a number of generations each year.

With the approach of Winter, breeding gradually ceases, and the half-grown scales hibernate over Winter, while the old and very young scales are killed.

The adult female scale is circular, slightly convex, and about the size of a pin’s head. The scale itself is greyish brown with a yellowy orange centre, and is merely a waxy secretion incorporating moulted skins.

The soft bodied, yellowish insect is circular and legless. The male scale is smaller and more elongated in shape. The

adult male insect is totally different from the female and is a delicate insect with a single pair of wings.

The San Jose scale can be controlled by a dormant application of Shell Redspray, Palespray or Universal Winter-spray. Lime sulphur can also be used, but is apparently less effective than oil emulsions.

In seasons which are favourable for its development the Rutherglen Bug may during the mid-Summer become a serious pest, particularly on stone fruits. Peaches, cherries and apricots may become so pitted by the bugs sucking the fruit that they are spoiled as either fresh or canning fruit.

The Winter is passed in the adult stage, the adults hibernating in grasslands and weeds, or sheltering under clods of earth and dead vegetation. In the early Spring eggs are laid in the soil, the leaves of grasses, or in the flower heads of certain weeds. The bugs are wingless when hatched, and pass through five immature stages before the winged adult stage is reached, usually in December. When their wings are developed they are able to travel great distances for food, attacking field and vegetable crops as well as fruit trees in mid-Summer, particularly in favourable seasons where there is considerable competition for food. There are numerous broods in a season.

The adult bugs are about 1/6" long, narrow bodied and brownish in colour. They have four gauzy wings and are very active.

The Rutherglen Bug is a particularly difficult insect to control, largely due to its very wide range of host plants and the consequent opportunities for rapid re-infestation; hence spraying with a contact insecticide serves little purpose.

The use of smudge fires may be a temporary aid in picking fruit before it is seriously damaged.

Clean cultivation is also recommended as it removes many of the bug’s alternate hosts and destroys favourable breeding places. DDT sprays have been used with great success against the Rutherglen Bug as a ground spray (Shell Ditrene ‘A’) and by spraying from aeroplanes.

1 he Bronzy Orange Bug is a pest in citrus orchards in New South Wales and Queensland, and at times causes considerable damage.

1 he bugs suck the sap from flowers, young fruit and stalks and cause them to fall. Young foliage and tender twigs which are attacked wither and die. The bug also ejects a foul smelling liquid which causes a certain amount of “leaf-burn”.

1 he yellowish light green eggs are usually laid on the leaves during February and March and hatch in 9-10 days. 1 he bugs grow by a series of moults, and in their immature stages are wingless and roughly oval in outline. At first they are glossy green, becoming lighter green, orange or pink in colour as they grow. The winged adults are reddish brown with a bronze sheen and are about an inch in length.

The bugs pass through the Winter in their early immature stages, in a more or less inactive state. In Spring they become active and feed on the new growth. There is only a single generation each year, with the adults most numerous from December to February.

The control officially recommended for this pest is the application of a resin-caustic-fish oil spray. This is very effective applied in the late Autumn when the insects are in an early stage of development.

More effective control is obtained using Shell Ditrene ‘A’ but it is necessary for this pest to use 0.2% p.p. DDT in the final spray. This is double the concentration at which it is normally used in horticulture.

These insects feed on the apple tree, causing curling and yellowing of the leaves and their premature fall. The fruit is also spotted with brown specks of excrement which are difficult to remove, except by washing the blemished apples before marketing. In addition the sugar in the excrement forms a suitable starting point for the growth of moulds when the fruit is stored or exported. This pest is also known to occur on pear, plum and cherry trees, but it is unable to maintain itself on these hosts over consecutive seasons.

A related yellow leaf-hopper can be found on weeds growing in orchards, but this form never feeds or breeds on apple trees.

The hopper passes the Winter as an egg buried in the bark of the twigs. These eggs usually hatch in early September, and large numbers of tiny yellow wingless nymphs may be found on the underside of leaves up to November.

Each insect passes through five wingless stages before the adult winged insects appear in late October or early November.

When the females reach maturity eggs are laid singly in the midribs and veins of leaves. These eggs hatch during January and the adults of the second generation appear from early February to March. This generation is the most injurious. The female insects lay most of their eggs in wood of the current season’s growth, and the insect overwinters in this form. The presence of insects up to May, June and July suggests that there is at least a partial third generation.

As the overwintering eggs are well protected under the bark they cannot be destroyed by spraying, so that any winter treatment is useless. Effective control can, however, be obtained by the application of at least one and preferably two nicotine sulphate sprays—the first of these being applied as soon as the nymphs of the first generation have developed wing pads, but before many adults are in evidence. This can usually be combined with the calyx spray against Codling Moth. Follow with a similar spray two or three weeks later.

The common or plague thrips are present every year to a limited extent, but occur in plague numbers only during the Spring and early Summer in years when the Autumn and Winter rainfalls have been above normal. The abundance and activity of the insects is then largely influenced by subsequent weather conditions, particularly temperature.

Apples, pears, peaches and plums may be heavily infested, apples the most seriously. Damage is caused as a result of the thrips feeding in large numbers on the blossoms, which wither and fall prematurely, preventing the setting of

The minute eggs are inserted just below the skin in all parts of the blossoms, and also in leaves adjacent to blossoms. After hatching, the immature forms usually cluster inside the blooms and feed mainly on the stamens. They may also feed on the young leaves. These immature forms resemble the adults in appearance except that they lack wings, which are developed later. When fully grown the larvae pass down

stages. Finally the adults emerge and fly back to the blossoms. Control Measures.

Due to the large number and variety of host plants the control of this pest is most difficult. Another factor in favour of the pest is that the eggs are protected by being placed under the skin of the plant.

Nicotine sprays however, can be used to keep the pest in check when it first appears. Winter spraying with a dormant type of oil such as Shell Palespray is useful on certain apple varieties, e.g., Rome Beauty. It hastens the break of dormancy and the trees blossom before appreciable numbers of thrips are present.

Shell Ditrene ‘A’ has proved very effective against a number of species of thrips, but no opportunity has yet been available to test it on a field scale against plague thrips. Because of its success against other species it seems very likely that DDT will be used at the first sign of plague thrips.

There are a number of different mites collectively known as Red Spiders of which the following are the most important.

The Bryobia Mite is the largest of the common plant feeding mites. It feeds on a wide range of plants and trees including most deciduous fruit trees, clovers and grasses. Injury is caused by the mites puncturing the leaf cells and extracting their contents, causing a characteristic bleached appearance. Severe attacks may seriously weaken the trees.

Hot, dry conditions favour these mites, hence the damage caused is most discernible during late Summer, especially in seasons and districts of low rainfall.

The eggs are bright red, smoothly spherical, and during early Summer are laid singly on the underside of the leaves. In late Summer and Autumn they are laid in masses on the rough bark of the spurs, at the base of laterals, and on stones lying on the ground.

These overwintering eggs hatch in mid-September, and adult mites appear by the middle of October. There are usually two or three complete broods during the Summer. Control Measures.

As can be seen from the life history, the most obvious method of attack is against the overwintering eggs, and this is usually done by using a dormant oil spray such as Shell Redspray or Palespray. The pest can also be checked in Summer by Shell Whitespray. ,

Vast increases in the population of these pests accompany the use of DDT sprays, due probably to the toxic effects of DDT on predatory and parasitic insects.

This mite feeds and spins fine webs on deciduous fruit and other trees. It is brownish red in colour, and its eggs are bright red, onion shaped and finely corrugated.

The injury caused by this pest is similar to that of the Bryobia Mite, but is often more serious as it is less dependent on weather conditions; severe infestations occur in wet as well as in dry seasons.

The life history is similar to that of the Bryobia Mite. The overwintering eggs are laid in similar positions and hatch about mid-September. Each female lays about 30 eggs, which during the Summer months hatch in approximately two weeks. There are probably three generations, but they are not distinct, and overlap each other.

This mite is usually called the “Red Spider” or “Red Spider Mite.” Although reddish in colour during the winter it is greenish yellow for most of the year. It feeds on a wide variety of plants, including the deciduous fruit trees, and is a serious pest in glasshouses. This mite is a profuse web spinner, and infested leaves become yellow and shrivel. Like the Bryobia Mite it is particularly injurious in hot, dry weather.

The Winter is passed in the adult stage, the mites hibernating in the soil and in cracks and crevices in the bark. Eggs are laid as soon as they become active in the Spring. The eggs are pale yellow, globular and hatch in about three days. The young mites reach maturity in about 12 days and live for a further two weeks.

Because of the habits of th's mite Winter control measures are impossible. In the Summer, however, spraying with Shell Whitespray is an effective check.

Vast increases in the populations of these pests accompany the use of DDT sprays, due orobably to the toxic effects of DDT on predatory and parasitic insects.

The Larger Horned Citrus Bug is a pest of major importance in Queensland citrus areas and in some seasons causes considerable damage. This very large insect causes damage by inserting its proboscis through the rind of developing fruit and feeding by suction.

The effects of its attacks differ somewhat according to the variety of citrus. Much of the affected fruit falls, but if it does not fall, it becomes yellow and dries out completely. Gumming is also frequently noticed on trees affected by this pest.

Lemons appear to be particularly attractive to this pest and are the type of citrus most severely attacked.

As is usual for this type of insect, there are seven stages in its life history—that is, the egg, five larval instars, and the adult or mature bug. The bugs overwinter as adults and egg laying is commenced early in September. There are four generations each year, these all overlapping to some extent.

There is a considerable variation in the times taken for development, the principal factors being temperature and the quantity of available food.

Control is very difficult, but providing sufficient measures are taken it is quite practicable.

In the early spring, the suggested control is to hand pick the bugs in the early morning and late afternoon—this will normally keep the trees clean until mid-summer. If this fails, fumigation with hydrocyanic acid should be carried out, but not earlier than November—this should control the pest till January.

Fumigation is again recommended at this stage, the orchard being covered as quickly as possible to prevent dispersion of the insects from untreated to treated trees. In some cases, a resin-soda-fish oil spray is used in place of fumigation, the normal strength being 10 lbs. of resin, 3 lbs. of caustic soda, U lb. of fish oil to 40 galls, of water.

Results obtained so far show that DD T gives very effective control of this pest.

The Soldier Bug is a large brightly coloured insect, hence its alternative name of Harlequin Bug. The adult bugs are yellow, red and brown on the upper surface and green underneath. This pest feeds by suction on garden plants, vegetables and fruit trees on rare occasions.

The life history of this bug is very similar to that of the Rutherglen Bug. The bugs overwinter as adults under the bark of trees and in dry litter.

If the bug migrates to tree or market crops, control may be achieved by dusting with a nicotine (not tobacco) dust or by spraying with a combined spray of 40% nicotine sulphate 1 in 800 and Shell Whitespray at 1 in 80. Kerosene emulsions may also be used for destroying the nymphs.

Infested vegetable gardens should be cleared of weed growth and debris in which the bug breeds.

The Woolly Aphid can be included in the category of highly destructive pests of the apple. It has gradually become widely distributed throughout the world and there are few apple growing regions free from this pest today.

The Woolly Aphid feeds by means of its piercing mouth-parts and as a result of its characteristic colony feeding typical gall like formations are produced on the infested branches and roots. In addition to this deformation, the vitality of the tree is seriously reduced by the continual sap removal. Infestation by this pest is serious in trees of any age, but it may even be fatal in young stock.

Woolly Aphids are dark purple or purplish brown in colour and are normally covered with bluish-white waxy threads. For most of the year wingless females capable of producing young without mating are on the trees, and it is only in late summer or early autumn that winged forms appear. Wingless females and young are also found on the roots, and there is a general but irregular and incomplete migration between the roots and the trunk and branches; upwards in early summer and downwards in late autumn.

Root damage, which may be serious, is controlled by using stocks resistant to attack by the aphid. These stocks, for example, Northern Spy and Winter Majetin, are now in general use. In the colder apple districts, the aphid is controlled on the upper parts of the tree by a parasitic wasp (Aphelinus mali Hald).

In the warmer districts, the parasite occasionally fails to establish itself, the aphid growing away before the parasite becomes active in early Spring. In these districts, Shell Palespray at a strength of 1 in 20 may be used during the winter, and during the growing period, nicotine sulphate at 1 in 800 combined with Shell Whitespray at 1 in 80; the latter being the preferred treatment. High pressure is essential.

Vast increases in the population of Woolly Aphid accompany the use of DDT sprays, due probably to the toxic effects of DDT on the aphid parasite, Aphelinus mali.

This scale pest of citrus is not such a voracious feeder as red or yellow scales, but when present is usually found in huge numbers and twigs may be killed. It is also serious in reducing the vigour of twigs leading to reduction in fruit size and also to attack by other pests. Sooty moulds thrive in large amounts upon the secretions of white wax scale, and this in turn leads to reduced photosynthesis and detracts from the appearance and value of the fruit.

Pink Wax scale which is not separately described here is almost identical in the type of injury caused and the recommended control measures, but is usually found in different areas to those showing white wax scale.

The pest passes through the winter principally in immature form. In spring maturity is reached and large numbers of small reddish eggs are laid beneath the waxy covering. The crawlers which hatch out mainly in early summer are also reddish in colour and are very active. After a short time they settle along the mid-ribs and veins of the foliage, and secrete a waxy covering above them with radiating waxy bands. At this stage they are about the size of a pin head and are most vulnerable to attack. Later the young scales crawl back to the twigs and branches and complete the rest of their development in a fixed position. They increase in size and produce wax at a greater rate until the form of the pest is lost beneath the prominent blob of wax. There is only one generation a year normally, and the insects spend some ten months on the twigs before reaching maturity and laying eggs in the following season.

The materials used to control white wax scale vary somewhat with the stage of development of the pest.

The preferred control must be carried out while the pest is in the “pinhead” stage on the leaves when Shell White-spray at 1 in 40 gives excellent control if applied thoroughly. Once this stage is passed the pest tends to move on to the stems and produces copious quantities of wax, from which its name is derived, and this wax acts as a shield against spray materials.

If through circumstances such as machinery break-down the preferred treatment has not been applied, the pest can be checked at the peak stage by a combination of washing soda 20 lbs., and Shell Whitespray 2i gals, in 100 gals, of water.

This scale pest is one of the commonest pests infesting citrus trees in the coastal citrus areas of N.S.W. and Queensland.

Light infestations of the scale are found mainly on the trunk and main limbs of the tree, but it can build up rapidly and spread on to the young twigs, leaves and even on the fruit when the infestation is heavy. The feeding of heavy infestations can seriously devitalise the tree and lead to splitting of the bark. Much dead wood may follow the attack.

It has been stated that the female produces young crawlers and these can be found practically all the year round (Queensland Agricultural and Pastoral Handbook, Vol. 111). These crawlers eventually settle down in depressions in the bark. The female is dull brown or almost black and becomes coated with dust particles so that it is difficult to detect. They are elongate and oval, but somewhat irregular in outline. The males, however, are conspicuously white, and in a heavy infestation give the tree the appearance of being whitewashed.

The pest overwinters in all stages, but principally as the mature female, giving rise to a noticeable brood in late spring. Young may be produced over a period of from 3-6 weeks by any female, and as the life cycle can be completed in 2-3 months the generations become confused and definite broods are not clearly defined.

This pest is rather difficult to control with scalecides, and to achieve good results it is necessary to use them at concentrations which limit them to the winter when the trees are less susceptible to injury. Lime Sulphur at 1 in 10 to 1 in 15 is commonly used with the addition of Shell Whitespray as a spreader and sticking agent. It should be applied in May to August, and at this time it will control the over-wintering females which otherwise give rise to the strong spring brood. The trunk and main limbs should be thoroughly sprayed from the inside, taking care to avoid spraying the fruit.

This pest, although readily controlled, can cause serious damage where it is present in large numbers. It infests twigs, leaves, wood and fruit. It is also responsible through its debilitating effect on the tree for the entry of melanose and other harmful conditions. The scale as its name implies is roughly mussel shaped and the mature female is nearly one-tenth of an inch in length. It is originally purple, but

The scale overwinters in the adult stage, and during this period and early Spring eggs are developed and laid, the average number of eggs produced by each female being 150. Hatching occurs in Spring from September onwards, the young scale reaching maturity by December-January. The eggs laid by this brood reach maturity in February to early March, and in this way four or five generations may develop in a year.

This pest is controlled by Shell Whitespray at a dilution of 1 in 40, as normally applied for control of red scale or other scale pests of citrus.

As production in the fruit industry increases, the threat of insect pests and diseases becomes potentially more dangerous, and their effect progressively more severe. For this reason the correct selection and application of sprays is of supreme importance.

To assist orchardists in this vital task, Shell offers quality products and accurate information. Highly trained research and field officers are continually at work, preparing and testing new materials for cheaper and better pest control.

Deakin University is not endorsed by or affiliated by the Shell Company of Australia

CITRUS.		SHELL SPRAY	SCHEDULE
Pest or Disease	State	Spray Material	When to Spray	Remarks
Red Scale Brown Olive Scale Purple Scale	Queensland N.SW. West Aust. Sth. Aust.	Shell Whitespray 2i : 100	When the crawlers first appear in early summer— usually December.	It is sometimes necessary to give a second similar spray in February to April. Where the spray-fumigation programme is used, control is effected by fumigation every few years and spraying annually.
	Victoria	Shell Whitespray 2i : 100	First week in December for early districts, and third week in December for heavy infestations of later districts. For these and for light infestations of later districts a similar spray in March is necessary.	Where fumigation is practised for heavy infestations of red scale, a December spraying should be given prior to January-February fumigation.
White Wax		Shell Whitespray 2i : 100	Pin-head stage on the leaf.	This spray cannot be delayed beyond the pin-head stage.

Fruit Fly

Queensland

Spray Bait:

Should be applied at six-

(Contd.)

Lead Arsenate 2\

Sugar ......2

Water ......4

oz.

lbs.

gls.

day intervals, when lures indicate the pest is active.

Treatment should be repeated if rain washes bait from trees.

Lure:

Vanilla: 1 teaspoonful.

Ammonia (household)

1 tablespoonful.

Water: 3 breakfast

cups.

Spray Bait:

Tartar Emetic or Sodium Fluosilicate 2 oz.

Sugar ...... 21 lbs.

Water ......4 gls.

Lure:

Pollard ...... 8 ozs.

Borax ......6 ozs.

Water ......1 gl.

Draw off clear liquid after allowing the above to stand overnight.

Spray Bait:

Juice of 12 ripe oranges.

Molasses or treacle: 4 lbs.

Lead Arsenate Powder: 2i ozs.

Water: 4 gls.

Other essential control measures involve orchard hygiene and bandaging. Notes on these will be found in Section 11

Remember that over-wintering grubs are the sole source of the following season’s infestation: their destruction is of great importance.

It is necessary to use lures to ascertain the peaks of moth activity. Control measures are -compulsory in some States.

Certain varieties of apples, such as Cleopatras and Five Crowns, are susceptible to spray injury; therefore, leave out oil from last cover spray for these varieties.

As the Codling grub often enters through the calyx, make certain the calyx cup is filled with spray.

If at the end of the season it is believed arsenical residue is inclined to be high because of late cover sprays, the lead arsenate should be eliminated or reduced, but oil sprays can still be given.

107

Pest or Disease	State	Spray Material	When to Spray		Remarks
Codling Moth (Contd.) f	Other States	Last Spray: Unless varieties are susceptible to oil spray injury eliminate lead arsenate from the last cover spray.			In South Australia, for varieties susceptible to arsenical leaf scorch, add 4 lbs. of slaked lime to each 100 gallons of lead arsenate spray.
	All States	Cover sprays of Shell Ditrene ‘A’ at 2J pints : 100 gls. (i.e., 0.1% p.p. DDT) may be used alternatively.			This programme will probably cause build up of other pests. See Codling Moth, Section 11, “Orchard Pest Control.”
San Jose Scale and Brown Scale	All States	Shell Palespray or Red-Spray, 5-7 : 100 or	Late as possible in mant season.	dor-	This will also control Mussel Scale in N.S.W. and Queensland.
	West Aust. and Victoria	Palespray...... 3 gls. Lime Sulphur 7 : 100	Late as possible in mant season.	dor-
San Jose and	All States	Shellicide “D” 1\ gls.	Spring.		In States other than N.S.W.

Pest or Disease	State	Spray Material	When to Spray	Remarks
Black Spot or Apple Scab	Queensland N.S.W. Victoria Sth. Aust. Tasmania	Bordeaux Mixture. 15 : 15 : 100 Palespray, i gl. : 100 gls.	“Green tip.” (For wet parts of Sth. Aust. this should be early “green tip” stage, and a 6:6: 100 Bordeaux should be given at the “closed cluster.”)	Bordeaux is more strongly recommended for control of Scab than is lime sulphur, but may cause some russet on sensitive varieties.
		Lime Sulphur, 14-24 : 100	Pink.
		Lime Sulphur, 1-2 : 100	“Petal-fall.”
		Lime Sulphur, 1-2 : 100	First cover.

This schedule may cause some From ^ open cluster to russet on sensitive varieties, but P'ⁿk.” better control of the disease is

Pest or Disease	State	Spray Material	When to Spray	Remarks
Black Spot or Apple Scab (Contd.)	West Aust.	Bordeaux Mixture, Apple 4 : 10 : 100 Pear 6 : 8 : 100 Shellicide ‘D’ i gl. in each case.	“Petal fall.”
		Bordeaux Mixture, Apple 4 : 10 : 100 Pear ..6 : 8 : 100 Whitespray, i gl. in each case.	Ten days later, if required, and thereafter at monthly intervals if required.
Pear	West Aust.	See Apple.
	Queensland N.S.W. Sth. Aust. Tasmania	(a) Bordeaux Mixture 15 : 15 : 100 Palespray, i gl.	“Green tip.”	(a) and (b) only for Josephine and Buerre Bose.
		Bordeaux Mixtures, 15 : 15 : 100 (except Q’land 7 : 5 : 100), plus Shellicide ‘D,’ i gl.	When leaf buds commence to open.	(a) Only for Winter Cole.
		(b) Lime Sulphur 1-2 : 100	White stage.
		(c) Lime Sulphur 1-1 : 100	If necessary, with lead arsenate sprays for Codling Moth.	If insect pests are present full strength oil can be combined at the “green tip.”

Pest or Disease	State	Spray Material		When to Spray	Remarks
Black Spot or	Victoria	Bordeaux oil sprays as		“Green tip.’’	Spray (c) and petal fall spray
Apple Scab		above (a).			for Victoria usually combined
(Contd.)		Bordeaux oil sprays as		Cluster stage.	with Codling Moth sprays.
		above (a). Bordeaux, 6:6:	100	Petal fall.	with Codling Moth sprays.
		above (a). Bordeaux, 6:6:	100	Petal fall.
Apple and Pear	West Aust.	Lime Sulphur 6 :	100	Bud movement.	Prune out and burn infested
Mildew		Lime Sulphur 2 :	100	Early pink stage.	wood during dormant season.
or Powdery Mildew		Lime Sulphur 1 :	100	At later stages. May be combined with lead ar-	Temperature during spraying should be below 75° F.

senate cover sprays.
Queensland	Lime Sulphur 4 :	100	“Pink” stage.
N.S.W.	Lime Sulphur, 1 :	100	Early green tip.	These sprays	are a	supplement
				to the Black	Spot	programme.
	Lime Sulphur, 1 :	160	Cover sprays with Codling Moth sprays.
Victoria	Black Spot schedule
T asmania	will control this	dis-
Sth. Aust.	ease.

See Black Spot.

Pest or Disease	State	Spray Material	When to Spray	Remarks
Shot Hole		Bordeaux Mixture, 15 : 15 : 100 Shell Palespray, i gl.	In autumn, as final leaves are falling.	If Red Mite also present, increase oil in first spray to 5-7 gls. : 100 gls.
		Shellicide "D” .. 1 gl. Plus Bordeaux Mixture. 15 : 15 : 100	Early pink bud stage.
	Queensland	Bordeaux Mixture, 15 : 15 : 100 or Lime Sulphur, 6 : 100	Bud movement.

Brown Rot and Freckle

Bordeaux Mixture,

15 : 15 : 100 Shell Palespray, i gl.

When buds commence to swell.

Remove and destroy mummies and burn prunings.

Bordeaux Mixture,

15 : 15 : 100 Shellicide ‘D\ i gl.

Pink stage.

If Red Mite also present, increase oil in first spray to 5-7 gals. : 100 gals.

116

Pest or Disease	State	Spray Material	When to Spray	Remarks
Fruit Fly		See under Citrus and Section II of “Orchard Pest Control.”
Oriental Peach Moth		Shell Ditrene ‘A’, 24 pints : 100 gls. (i.e., 0.1% para para DDT)	Spray generally 6 and 3 weeks before harvest if it is known moths will be active.	Timing of these sprays may be modified to coincide with maximum moth activity.
Rutherglen Bug		Shell Ditrene ‘A’, 24 pints : 100 gls. (i.e., 0.1% p.p. DDT)	When pest appears.	DDT sprays have proved effective when applied by aeroplane and by normal spraying.
San Jose Scale Brown and other Scales		Shell Universal DNC, Winterspray, 24 : 100	Late dormant season, before buds show first signs of bursting.
Bryobia Mite, Red Mite and Red Spider		Shell Universal DNC, Winterspray, 24 : 100 If this dormant spray	Late dormant season, before buds show first signs of bursting.	Red Spider does not overwinter in the egg stage and cannot be controlled by the dormant spray.

was not applied,

Shell Whitespray,

117

Pest or Disease

State

Spray Material

When to Spray

Remarks

Root Borer

Round the trunks of the trees place a verandah made by bending zinc or tin sheeting. Collect the beetles which accumulate and destroy them. Sticky bands are also effective. DDT painted on the butt below the band will probably give good control.

Brown Rot

Sth. Aust.

Bordeaux Mixture,

15 : 15 : 100 Shellicide ‘D’, i gl. Lime Sulphur,

li : 100 Lime Sulphur,

li : 100

Pink bud.

Petal fall, i grown. i grown.

Additional sprays of Lime Sulphur li : 100 are recommended at any period of extended wet weather.

Colloidal Sulphur should be At weekly intervals to used where coastal varieties do fruit set. not tolerate Lime Sulphur.

N.S.W. Bordeaux Mixture,

(M.I.A. only) 15 : 15 : 100

plus

Shellicide ‘D’, 4 gl. Bordeaux Mixture,

14 : 1 : 80 plus

Whitespray, 4 gl. Bordeaux Mixture,

14 : 1 : 80 plus

Whitespray, 4 gl.

Other States Bordeaux Mixture,

15 : 15 : 100 plus

Shellicide ‘D’, 4 gl. Lime Sulphur,

14—lf : 100

Dry-mix Sulphur Lime.

1 20

CHERRY AND	PLUM.
Pest or Disease	State	Spray Material	When to Spray	Remarks
Black Cherry Aphid		Shell Universal DNC Winterspray, 24 : 100	Spray late in dormant season, against over-wintering eggs, but be certain to complete spraying before 31st July — i.e. , before bud burst.	This spray also controls Red Mite and San Jose Scale.
		Shell Whitespray, 1 : 100 gls. Plus Black Leaf 40, 1 pt.	As soon as Aphids observed. DDT shows great promise for this pest, but is still under review. Refer Section on DDT in the text.	This application should be made if winter control has been omitted. Spray as early in foliage stage as possible before leaf curling becomes complete.
San Jose Scale		If no Black Cherry Aphid use Shell Pale- spray ...... 5-7 : 100	Spray late in dormant season.	Shell Universal DNC Winter-spray for Black Cherry Aphid controls this pest.
Bryobia Mite and Red Mite		If no Black Cherry Aphid use Shell Pale-spray ...... 5-7 : 100	Spray late in dormant season.	Shell Universal DNC Winter-spray for Black Cherry Aphid controls these pests.
Pear and Cherry Slug		Shell Whitespray, 1 gl. Lead Arsenate: 14 lb. of powder or 3 lbs. of	Apply when the pest is observed.

Pest or Disease	State	Spray Material		When to Spray	Remarks
Hawk Moth Light Brown Apple Moth Silver Striped Vine Moth Vine Moth		Lead Arsenate Powder .......... 3 lbs. Water...... 100 gls.		In the spring.
Vine Weevil		Bait: Calcium Arsenate, 1 oz. Bran.......... 1 lb. Water, 1 pt. (approx.)		Applied around butts of vines in small heaps when observed.	Causes complete defoliation of the vine.
Greater Vine Scale		Shell Palespray or spray .. .. 5-7 : Shell Whitespray, 2i :	Red- 100 100	During winter, after pruning. If necessary when young scales appear in summer.	If possible prunings should be burnt near the vine to avoid spread.
Bunch Mite or Vine-berry Mite		Lime Sulphur, 10 :	100	Late in winter, just before buds begin to swell.	A brownish scaly or corky incrustation associated with these mites may be found on the grapes and stalks.
		Colloidal Sulphur, 2 Soft Soap .. .. 4 Water...... 100	lbs. lbs. gls.	When new growth is between 12 in. and 18 in. long. Second application three weeks later.

It is a common sight in orchards to see tree wounds, sometimes exposing large areas of wood. These wounds comprise broken limbs due to heavy cropping, bark wounds and fractures which have been caused by soil cultivation implements and, in some cases, damage caused by heavy falls of snow. The removal of large limbs then becomes necessary. It is also quite often essential to remove large limbs during pruning and grafting operations. Whatever the cause of the wound, some system of tree surgery must be used to keep the tree bearing and to prevent these wounds becoming affected by wood rot fungi. The instructions given below apply to any form of tree surgery.

When removing a main limb from a tree, first make a clean cut with the saw to a depth of on the underneath side. This will prevent premature fracture and splitting during the sawing operation. It is most important that the saw cut be made at an angle which will leave the smallest area to heal over. It is then necessary to trim all the rough surfaces smooth with a sharp knife. Owing to the prevalence of the fungus Polystictus versicolor, saw cuts must heal over as quickly as possible, and a thorough dressing with one of the Shell Grafting Mastics is recommended. Grafting Mastic “L” is applied by hand-working, and Grafting Mastic “H” by melting it and painting or working it on to the cut. Shell Colgraft is widely used for this purpose also.

First remove the soil from around the butt of diseased trees and discover how far the roots are affected. If any badly diseased roots are found, these should be completely removed. The main roots within a radius of about 3 feet from the butt should be left exposed for some months afterwards to allow the admission of sunlight and air. The method of treating the diseased parts is to take a sharp, heavy knife and remove all diseased bark, together with one or two inches of the apparently healthy bark all around the diseased area. This is done by making vertical cuts into the bark and inserting the knife blade between the bark and the wood, thus removing the bark in strips. The wounds should then be painted over thoroughly with a fungicide, Bordeaux Paste being recommended for this purpose.

Crown gall is a parasitic organism and is found on many plants. It is most serious in stone fruit trees. The infection is mainly introduced from the nursery at planting. Organisms may persist in the soil for some considerable time, so that the continued use of the ground where infected trees grew for nursery trees or for re-planting is most unwise.

Infection of the trees is first noticeable when gall-like growths are apparent, usually about the crown of the tree. The galls, which are small in the early stages, gradually develop to a large size.

Despite repeated experiments, no satisfactory method of controlling the disease in either nursery or orchard has yet been evolved. At planting, any affected trees should be returned to the nursery or destroyed. It may even be best to refrain from planting the consignment of trees, if the percentage of affected trees is considered high.

If the trees are in bearing, there is little that can be done to reduce or combat infection, but luckily trees may crop satisfactorily for many years despite the appearance of the disease. Control of crown gall in the nursery seems to be the most hopeful line of approach. Investigations in U.S.A. have shown some promising results which are being investigated in Australia. At the present time these are only in the experimental stage, and no recommendations can be made other than for adequate orchard and nursery sanitation.

An infection causing gumming and die-back of stone fruit trees has been found in various parts of New South Wales. No control measures can be recommended at the present stage, but since the organism is most active during winter and spring, late summer or early autumn pruning is recommended.

One cause of root rot in many fruit trees is armillaria. If the soil is removed from around the butts ot trees and the main roots exposed, the tree attacked by this fungus will show

a rotten condition of the bark at and below the ground line. Bark can readily be peeled away, exposing the white fungus lying between the bark and wood.

The treatment of this disease is similar to that of collar rot, i.e., remove the soil from around the butt of the diseased trees and discover how far the roots are affected. If any badly diseased roots are found, these should be completely removed.

The main roots within about a radius of 3 feet from the butt should be left exposed for an indefinite period afterwards, to allow the admission of sunlight and air. All diseased bark, together with one or two inches of the healthy bark around the diseased area, should be removed, and the wounds then painted over with Bordeaux Paste. Trees in an advanced stage of the disease should be removed.

Bordeaux paint is simply Bordeaux Mixture, but with such a small quantity of water that a paint or paste is produced. The method of preparing it is as follows:—

Take H lbs. bluestone (copper sulphate) and dissolve in approximately one gallon of water. Then take 1 lb. of lime which is broken down with approximately one gallon of water. This is then poured into the blue-stone solution to form the paint.

NOTE: Bluestone should always be dissolved in a wooden or earthenware container; iron or galvanised iron vessels must not be used.

Plant propagation is an artificial means of increasing the number of plants normally produced by any species.

Fruit tree propagation is an art which can only be learned by making a thorough study of its fundamental principles, and the skill required can only be gained through practice. Only a brief outline of the process can be given here, to indicate the main essentials which must be adhered to as far as the commercial orchardist is concerned. For instance, seedling or clonal root stocks must be tested out for many years before they can be recommended for working on to them various commercial varieties, as such things as incompatibility, transmission of disease, scion influence over stock, stock influence over scion, etc., must be closely studied.

Various methods of grafting and budding must also be studied, a knowledge of the sealing of grafts, and the after care of grafts and buds being most essential for success. Full information on fruit tree propagation is readily available in pamphlet form from State Departments of Agriculture.

Budding offers a ready means of changing over the production of a tree to a new variety without replanting the tree. Use is made of the existing healthy stock to carry the new wood. Like grafting, it is an art which cannot be explained in a few

paragraphs, and practical experience is the best teacher, hence only a general outline of the process is given here.

Budding is done when the sap is running freely—in December, January and February—and the buds inserted on the current year’s growth. Citrus trees are budded in March-April or September-October. Only well developed buds from high-yielding trees should be used. In removing the bud the cut should not be made too deeply. The small piece of wood cut with the bud should be removed from apricot, peach and cherry buds, but on apple, pear, plum and citrus a thin piece should be allowed to remain. The small ‘‘pinpoint” of wood running to the eye of the bud should never be removed, otherwise the bud will be useless. The stalk of the leaf is left on the bud and used as a handle when putting it into place.

The bud is inserted just under the bark and the cambium layer, which is the soft, greenish colored tissue between the bark and the wood. The illustrations show the steps to be taken from the T-shaped cut at A to the final tying-up of the bud with raffia or string.

A good union should be apparent after a few weeks, when the tie can be cut or loosened. The bud from a deciduous tree, or from the autumn-budded citrus, remains dormant till the Spring. Citrus buds inserted in Spring however will make growth the following summer. Cut off the old wood just above the new bud sometime in the Winter or Spring, as the new growth from the bud will become the main arm of the tree at this point.

To bud over old trees, it is more usual to cut the trees back hard during the dormant season, and bud into the new Spring growth which follows, especially with citrus trees.

GRAFTING

This is the most popular method of working over all kinds of nursery stock, including root grafts, and stocks in which dormant buds have failed are usually worked in this way.

The stock is prepared by making a flat sloping cut from. H to 2 inches long, and then at a point about a third of the way down from the top of the main cut, another shorter cut, about i" to f" long, in the opposite direction.

The scion is prepared in exactly the same manner, and stock and scion are then joined together by inserting the tongue of the scion into the cleft on the stock and forcing them firmly into place. If stock and scion are approximately the same diameter, a very neat join will result, but if the stock is larger than the scion, the latter should be placed over to one side of the stock cut, in order that the cambium layers of both may be in contact on one side. When in position, the graft should be tightly tied and effectively sealed with one of the Shell Grafting Mastics.

This is an excellent graft for small limbs. Although once used extensively, it is not as suitable for large limbs as a strap or a bark graft.

The limb to be grafted is cut off where desired, and split about 2" in depth across the cut surface. The scions are cut wedge - shaped, with the outer edge a shade thicker than the inner one so that the stock will hold it firmly at the point where the union takes place, i.e., the cambium layer between bark and wood. When inserting the scion care must be taken to see that the cambium layer of both stock and scion are in contact.

After insertion the graft should be tied and thoroughly sealed with Shell Grafting Mastic.

The bark of the stock is split down for an inch or so, and loosened at the top to allow entry of the scion. The scion is prepared by making one main sloping cut about li inches in length, and then taking a thin slice of bark and wood from the back of the point of the cut, thus making a chisel-like point which facilitates pushing the scion down between the bark and the wood of the stock. The scion is then pushed home, tied tightly and sealed. This style of grafting is best done when the sap is flowing fairly freely.

The strap graft is an improved type of bark graft; the stock wounds heal over much more quickly, and there is little chance of wind damage, as with ordinary bark grafts. It takes a little longer to prepare the scions and the stock, but the advantages are well worth the little extra trouble. Strap grafting is eminently suitable for the ends of the limbs when re-furnishing, and for large cuts such as result from stump-grafting. In the latter case, it is mostly used with supplementary bark-grafts to ensure quick callousing of the wound.

This graft is prepared by a similar method to that described for the “rind” graft, except that, before making the diagonal cut, a thin piece of bark with some wood attached is cut upwards on one side of the scion. This is then laid back and the graft completed. When it is inserted, the “strap” is brought over the top of the tree limb and tacked under a piece of bark which is raised on the opposite side. This is one of the neatest methods of grafting limbs where a large surface has to be healed over, and although it takes longer to do, the results are well worth the extra labour.

The principal cause of failure with strap grafts is cutting the strap too thin, and care should be taken, when cutting, to see that a good piece of wood, as well as bark, is incorporated in the strap.

A system of reworking trees which renders them far less susceptible to attack by wood rot fungi and, in addition, causes the trees to crop several years earlier than those worked by the stump method, has been developed. This system is known as refurnishing, and though the actual details of the operation may vary slightly according to the operator’s ability and views, the principle is basically the same, i.e., to retain as much of the tree’s original framework as possible or desirable, and to replace the fruit-carrying surface of the tree with the desired variety. Naturally, this method is more costly than the old way, but its advantages more than compensate for the increased initial expense.

The first operation is to strip the tree of all laterals and fruit spurs. The main limbs are cut back and only a skeleton framework is retained. This can be done at any time during spring when the bark lifts freely. Rind or strap grafts are then inserted at the terminals of the main branches.

For side grafts, an inverted L-shaped incision (thus ~j) is made through the bark at an angle of about 40-45 degrees to the axis of the limb. The long cut of the L should be about li inches in length, and the shorter cut about i inch.

The corner of bark in the angle of the L is raised and the scion—prepared as illustrated on this page, but with a thin sliver of bark pared from the side adjacent to the long cut of the L which is not lifted—pushed well under the raised flap of bark, and a fine tack or panel pin then driven through the bark and scion into the main limb to hold the scion firmly in position. The graft is then sealed to exclude air and moisture.

Where the bark of the stock tree is fairly thick, it is advisable to remove a tapering slice of bark above the angle of the L so that the scion will fit neatly on to the wood of the stock. If this is not done, the scion will be squeezed against the edge of the bark underneath, and a weak spot in the union will result.

The handiest and best method of making the incision in the bark is by means of a small L-shaped punch—easily made by any blacksmith.

The matter of spacing the scion should be kept in mind when stripping the trees, and if it is desired to utilise laterals and small limbs, etc., for stub grafts, it should be remembered that the idea is not necessarily to refurnish the tree with approximately the same number of spurs, laterals, etc., as appeared on the original tree.

Most of the new grafts, if treated correctly, will develop, if required, into small limbs, thus it is needless waste of time and material to put on more scions than required. Generally speaking, if the scions are spaced 8" to 10", or even 12" apart, there will be ample for the purpose.

Both these items are of great importance, and a little extra time spent on them is well worth while. When selecting wood for grafting purposes, care should be taken that it is obtained only from the best type of trees available, i.e., mature trees which have consistently borne heavy crops of good quality fruit. Select only well-matured wood of the current season's growth, with well developed buds and free from pest or disease. The best developed buds are formed on about the centre half of a lateral; therefore, avoid using the butt ends or tips, if possible.

Laterals carrying weak or latent buds, and also strong growing water-shoots, should be avoided.

A good supply of scions should be collected, as it is poor policy to skimp the grafts, and the selected wood should be of varying thickness—the larger ones for strap and stub-grafts and the remainder for bark side-grafts.

Several methods of storing scions, until required, have proved satisfactory and simple. If cool storage facilities are available, the scions may be simply tied in bundles and held at ordinary fruit temperatures for short periods. For comparatively long storage periods, however, it is advisable to pack the wood in layers with moist sand in boxes.

If cool storage is not available, or for any reason is not convenient, the scions may be buried in a cool, moist place until required. The spot selected for burying the scions should be well drained, and, if long storage is desired, should be in such a position that the sun does not shine on it. The wood may be completely buried, being spread out in a fairly thin layer on the bottom of the trench and covered with hessian to prevent it becoming too dirty, and at least 4 or 5 inches of soil placed on top. Heeling-in the scions to about half their length is satisfactory for short periods, provided the site chosen is cold and free from the sun. All scions for keeping should be cut from the tree as late as possible, but whilst still completely dormant.

Inarching is a method of grafting by which young seedling trees are planted near the butt of an older tree and grafted on to either the stem or limb of such tree.

The system may be used to “repair” old trees damaged by rabbits or some other agency, or to rejuvenate an old tree which has an injured or weak root system.

The best method is to plant at least three or four well-grown yearling whip trees equidistant around and as close to the trunk as possible. The trees may then be inarched into the trunk or limbs according to the damage.

Because of the nature of this operation whip, cleft or strap grafts cannot be used. The top of the young stock is grafted to the tree by means of a modified sidegraft and consequently must be done when the sap is running freely. It is sealed with the appropriate Shell Grafting Mastic in the same way as other grafts.

A scion long enough to bridge the injured portion is grafted into sound tissue below and above the injury, thus providing a channel to carry the sap across the injured part.

This is a valuable method of overcoming ring-barking of the butts of trees by rabbits, etc.

Grafting Mastics, as the name implies, are used by or-chardists, after pruning and grafting, to seal cuts and wounds on fruit trees to prevent the entrance of wood rot fungi.

The main function of a Grafting Mastic is to seal the wounds and grafts thoroughly so as to render these^ wounds air and water tight and allow the cut surfaces to unite. Simple as this operation is, very poor “takes can be traced back to faulty sealing. Even if only a small hole is left particularly between the scion and the limb—there is a very good chance of the scion “missing."

Considerable care should be taken over the sealing process. The mastic must, therefore, be easily moulded, but, at the same time, it must have setting properties which give a certain rigidity to the graft. However, any material which may prove toxic to the tree or the graft must be excluded.

In areas with high summer temperatures, crude petroleum jelly is unsafe to use, as it has a tendency to melt during very hot days. This can cause considerable damage to the newly-formed callous and bark tissues, and the damage forms ideal starting points for wood-rot fungi such as Polystictus versicolor.

For refurnishing, Grafting Mastic “L” is ideal. It requires no heating, even on the coldest of days. Callous forms readily under Grafting Mastic “L.” It will melt, of course, but nevertheless will withstand much higher temperatures than crude petroleum jelly. Mastic “L” is excellent for stump grafting also, provided that cuts are not large, in which case either Mastic “H” or Colgraft is preferably used.

This has a higher softening point than Mastic “L” and cannot be readily moulded by the fingers. Preferably it should be melted and brushed on to the wounds and around the grafts. It is particularly useful for covering large wounds such as occur in stump grafting, where Mastic “L” would melt in very hot weather. It is also recommended for use in the root grafting of nursery trees. For this purpose it is unexcelled.

A durable bituminous emulsion with excellent working qualities, Colgraft is widely used in stump grafting and in the pruning of large limbs.

Colgraft can be thinned to any desired consistency with water. Excessive dilution will cause poor “takes” due to cracking around the graft. To cover large saw cuts, it is best to thin Colgraft down a little more than for normal grafting, to enable it to be brushed on with ease. When used in this way it is much superior to ordinary types of paint.

Colgraft is unsuitable for root-grafting because it is too durable, and prevents the raffia tying material from rotting in the ground. Mastics “L” and “H” are superior in this respect.

SHELL

Here are pictures of a £ 100,000 investment —Shell's new Agricultural Laboratory in California. The 142 acre site was specially selected to allow the widest possible range of trees, vines and field crops to be grown on a commercial scale. New developments in the twin sciences of plant nutrition and pest control will be studied and tested in the laboratories, the greenhouses, and finally under field conditions.

Petroleum is a natural storehouse of valuable products for the agricultural industry, and from the Shell Agricultural Laboratory will come new materials and new scientific techniques to improve food crops all over the world.

Aerial view of the laboratory buildings and part of the surrounding experimental farm. Behind the laboratory and administrative building, lie the three greenhouses with connecting head house, and a large lath house. The garage and service building stands nearby.

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Aviation Gasolines.

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Cross Power Kerosine. Diesoline.

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Fuel Oil

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Shellite for petrol stoves, irons, lamps, etc.

Mineral Turpentine.

White Spirit.

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Naphthenic Oil Residue.

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Industrial Oils and Greases.

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Specialised Cutting Fluids.

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Malariol.

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Bordeaux against most citrus		diseases.
Solution A		Solution B
Copper sulphate ........	1 lb.	Caustic Soda ............	5 ozs.
Molasses or honey ....	1 pint	Water ...................	3 pints
Water ....................	4 pints

Pest or Disease	State	Spray Material	When to Spray	Remarks
Pink Wax		Refer White Wax Scale	Refer White Wax Scale.	If allowed to mature the wax becomes very hard, and spraying has little effect.
Rust Mite or Silver Mite	Queensland	Lime Sulphur 7 : 100 „ 34 : 100	Pre-blossom stage in early August. November to early December.	Damage to the fruit commences when it is only 4 in. to 1 in. in diameter, and control measures should be undertaken then.
	N.S.W.	„ „ 24 : 100	Early December.	Damage to the fruit commences when it is only 4 in. to 1 in. in diameter, and control measures should be undertaken then.
	Victoria Sth. Aust. West Aust.	„ 4-5 : 100	November to early December.	Damage to the fruit commences when it is only 4 in. to 1 in. in diameter, and control measures should be undertaken then.
Aphids		Shell Whitespray 4 gl. Black Leaf 40 .. 1 pt. Water...... 100 gls.	Sp ay as soon as observed.	An early spray is necessary to prevent injury to young growth
Bronzy Orange Bug Larger Horned Citrus Bug Curculio Beetle		Shell Ditrene ‘A’ 24 pints : 100 gals (i.e., 0.1% p.p. DDT)	When observed.
Bronzy Orange Bug Larger Horned Citrus Bug Curculio Beetle	Alternative	Resin ..... 25 lbs. Caustic Soda 74 lbs. Fish Oil...... 4 lbs.	Early November and again in January.

Pest or Disease	State	Spray Material	When to Spray	Remarks
Soft Brown Scale		Shell Whitespray 24 : 100	Early summer.
Cottony Cushion Scale		Shell Whitespray 24 gls. Black Leaf 40 .. 1 pt. Water...... 100 gls.	When pest is in very early stages.	Similar spray may be necessarv three weeks later.
Orange Piercer Moth		Shell Whitespray 24 : 100, plus standard lead arsenate as used in Codling Moth in Apples.	When observed.	Some tests indicate that 0.2% p.p. DDT sprays are effective for controlling this pest. If this is so, Shell Ditrene ‘A’ at 44 pints : 100 gls. should be used.
White Louse		Lime Sulphur 7 : 100 to 10 : 100.	May to August.	Trunk and main limbs should be sprayed from the inside of the tree. Do not spray the fruit.
Dicky Rice Weevil		Band the tree trunks with sticky tree banding material	Banding should be completed by 1st August, and maintained in an effective condition until December.
Fruit Fly	Queensland	Lure: Rind and rag of a ripe orange 24 in. diameter, 6 teaspoons 18% aqueous ammonia, \| pt. water.	Commence luring full scale in late February. Keep “pilot” lures until late maturing fruit, such as Valencias, have been harvested, so that sudden influx of flies may be de-	Each trap requires about 6 fluid ozs. of lure, and should be recharged every six days. The location of traps is dependent on the size and distribution of trees.

Pest or Disease	State	Spray Material	When to Spray	Remarks
Exanthema		Bordeaux Mixture— 7:5: 100. or Soil application of bluestone, 1 to 4 lbs. per tree.	Spray at blossoming. Apply in early spring or in autumn.	Drainage, application of farmyard manure and resoiling are also control measures.
Melanose	Queensland	Cuprous Oxide Mixture—3 : 40.	Half to three-quarter petal fall.
	N.S.W.	Bordeaux Mixture— 4 : 4 : 100 Plus Shell Whitespray: i gl.	Immediately after all the blossoms have shed their petals.	The use of Shell Whitespray with the Bordeaux vastly improves its efficiency because of better sticking and spreading.
Brown Spot (Mandarins)	Queensland	Cuprous Oxide Mixture—3 : 40.	1. Half to three-quarter petal fall. 2 Two months later. 3. Late February.	Thinning out crowded limbs and inside growth is recommended. Avoid severe pruning.
	Other States	Bordeaux Mixture— 2 : 2 : 100. plus Shell Whitespray: i gl.	A half to three-quarter petal fall, also 5, 10 and 15 weeks later.
Citrus Blast and Black Pit of Lemons		Bordeaux Mixture— 6:6: 100. plus Shell Whitespray: i gl.	Apply in Autumn. Where infection has been severe applications should also be made in Spring.	Occurs mainly on lemons, and particularly exposed trees, hence it is desirable to shelter trees as much as possible. Appears as black depressed spot g in. to i in. diameter.

Pest or Disease	State	Spray Material	When to Spray		Remarks
Collar Rot (Gummosis)		Cut away diseased parts carefully, - and paint the wound with Bordeaux Paste.	Whenever observed.
Brown Rot	Sth. Aust.	Bordeaux Mixture—■ 6:6: 100. Plus Shell Whitespray: 4 gl.	At onset of wet weather.	Clear trees.	away cover crop beneath
	Other States	Bordeaux Mixture— 4 : 4 : 100. Plus Shell Whitespray: 4 gl.	Early April, or immediately after the first autumn rains.	Prune with trees.	away branches soil, and spray	in contact soil under
Leaf Yellowing		Apply dolomitic limestone (1 to 2 tons per acre) to the soil.	At any time other than simultaneously with nitrogenous fertilisers.
Septoria Spot		Bordeaux Mixture—-4 : 4 : 100. Plus Shell Whitespray: 4 gl.	In March, before autumn rains, and in spring if necessary.

Pest or Disease State	Spray Material	When to Spray	Remarks
San Jose, Brown Olive and other Scales	Shell Palespray or Shell Redspray 5-7 : 100	Before buds burst.
Fruit Fly	See Citrus Schedule and Section 11 of “Orchard Pest Control."
Apricot Beetle	As for Codling Moth
Looper Caterpillar	See under Schedule for Apples and Pears.
Bryobia Mite Red Mites.	Shell Palespray or Shell Redspray, 5-7 : 100 Alternatively, Shellicide “D” 2i : 100	Before buds burst. Up to “pink bud” stage.	Red Spiders, as distinct from the Mites, cannot be controlled in the dormant period Combine with Bordeaux for Shot Hole or Brown Rot.

eefo’on

COM PAT I B! LIT Y CHART

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