HOME ORCHARD

Wairarapa Times-Age, 25 October 1939, Page 3

HOME ORCHARD

INSECT PESTS & FUNGUS BLIGHTS BEST MEANS OF COMBAT. VARIOUS TYPES OF SPRAYS. (Bulletin published by the Department of Agriculture.) This bulletin is published in response to numerous inquiries from the occupiers of the smaller farm and suburban orchards. The directions are given in an elementary form to suit the special requirements for the control of codling-moth, scale insects, woolly aphis (American blight), red mite, black-spot of apples and pears, powdery mildew of apple-trees, and peachcurl in such orchards. The accepted method of dealing effectively- with these orchard pests and blights is that of spraying, different sprays being used as required. For instance, the codling-moth grub, which directly feeds upon the fruit, is destroyed by keeping the fruit covered with a film of arsenate of lead during the few months when this pest is active. It has been found that this compound renders the skin, when eaten, toxic to the insect, which is thus destroyed. On the other hand, scale insects, wooly aphis, and red mite feed upon the juices of the fruit, stem, and foliage by means of a beak which penetrates the surface and sucks up the natural juices of the plant. For such pests, it will readily be seen, arsenate of lead would be useless as a remedy. The present method is to destroy them with a contact spray, which is effective as soon as they receive a coating of the mixture, this being generally of a caustic or oily nature. Black-spot on the apple and pear is a deformity of the surface of the fruit, which is not due to insects at all, but a parasitic fungus, for the prevention of which a different spray, again, must be used. During the period of the year when this blight is prevalent it is customary to cover the surface of the fruit-tree with a spray, which prevents the almost invisible spores of the fungus from germinating and establishing themselves in the fruit or leaves. POWDERY MILDEW. Powdery mildew attacks the leaves, shoots, blossom buds and also causes a web-like russet on affected fruits. On the foliage it appears as greyish, cobwebby patches, giving the affected areas the appearance of having been dusted with flour. The affected shoots take on a white, glistening appearance, become bare of foliage, and ultimately die. Infested blossom buds become covered with a greyish-coloured mycelium of the fungus. The diseased blossom bud clusters are usually smaller in size than the healthy clusters, and rarely set fruit. ,

The early spring prior to the “petalfall” stage of the flower is the appropriate period to apply sprays for the control of this disease. Sulphur sprays, such as lime-sulphur and colloidal sulphur, are the specifics recommended to keep this disease in check. Money and time are often spent on spraying without obtaining the expected results. This is because it is not properly performed. A few points which will ffialfe for effective work are given here. SPRAY-PUMPS. The effective spraying of the home orchard requires a pump in good order. For a few trees the well-known bucket pump is quite suitable, but it should be clean, and the packing and unions tight. The small length of hose usually supplied with the pump is unsuitable for orchard spraying. Bft of good Jin hose and a 4ft directing-rod improve the outfit very much. To do good work requires one person to carry the bucket of spray and pump and another to apply the spray to the trees. This operation must be done thoroughly and systematically, for most of the pests and blights shelter in the angles of twigs, under the leaives, and in abrasions of the bark of the tree. Commence at the top and work downwards giving .as much attention to the inside of the tree as is given to the outside parts. Consider the windage, and work in dull weather, or afternoons is possible. For larger areas a barrel pump, is more suitable than the bucket pump. ATTENTION TO DETAILS. Another important point affecting results is the preparation of sprays. Buckets used for oil should not be used for bordeaux mixture or lime-sulphur without being washed, or vice-versa; it is a good plan to keep separate vessels for the purpose. Weighing and measuring of ingredients must be accurate. A little too much or too little may burn the trees and cause loss of the crop. When mixing have a batten handy to stir the mixture well, and again occasionally, while applying it, so as to prevent any settlement of the ingredients. SPRAY.AT THE RIGHT TIME. To be effective sprays must be applied at the right time. Codling-grubs are feeding in November, and are about until February and March, the period varying slightly with locality. Scale insects are dealt with at almost any time, but are more easily destroyed in early spring just before their eggs begin to hatch. Woolly aphis is most dangerous in autumn, when winged emigrants appear, which establish new colonies. Red-mite eggs, which are often found about the base of leaves and twigs, hatch in early spring, and. egglaying is active about the month of March in such places; effective work can be done by spraying at these times. Black-spot spores issue in early spring from the fungus wintering on leaves and branches; they are so small as to be invisible, and settling on the leaves and fruit, under suitable conditions, make root-like growths which penetrate the tissues of the host. Usually the most dangerous period is during September, October, and November. Powdery mildew spores become active early in the spring at the time the buds are swelling. Suitable measures taken during September, October, November and December will do much to control this trouble. These facts are given to show the

importance of spraying at the time mentioned in the directions which follow. i CODLING-MOTH. Considerable loss results each season from the depredations of codling-moth in apples, pears, and quinces. This can easily be remedied by careful and systematic spraying with arsenate of lead. Although it may not 'appear so. codling-moth is one of the easiest insect pests in the orchard to control, always provided that the main principles are adhered to —namely, correct strength of arsenate of lead and thoroughness of application at the correct times. A knowledge of the habits of this insect at once indicates a method of intelligent control. We have learned that (1) it lives by eating the fruit, therefore we cover the latter with a weak poison, such as arsenate of lead, thereby destroying the grub;. (2) the grubs hatch in late spring and through summer from eggs laid by the female moth on the young forming fruit or leaves, consequently we commence spraying the young forming fruit early, and continue at frequent intervals throughout the summer; (3) as a large proportion of the grubs enter through the eye or calyx end, we endeavour to fill the calyx cavity with spray before it finally closes; (4) the grub changes into a moth, the female of which will lay eggs to hatch into more grubs, and we must therefore destroy all grubby fruit to reduce the numbers for further infection. SPRAYING TREATMENT. From these considerations, therefore, the following spraying treatment is recommended: — Proportions. —Arsenate of lead powder form, loz (if in paste form 2oz); water, 4 gallons. Preparation. —Weigh out loz of arsenate of lead (powder) and place in a small vessel; slowly add a very small quantity of water, mixing thoroughly all the time. When the whole is about the consistency of milk pour into a kerosene-tin or other vessel and make up to 4 gallons with water. This wash requires to be frequently stirred while beinfe used. Application.—Spray when two-thirds of the blossoms have fallen, with considerable pressure, and force the liquid into’ the “eyes” of the young fruit. Repeat every three weeks until February. Future applications will depend on district and climatic conditions. Usually it is necessary to spray towards the middle of February, and in some of the northern districts again a month later. These late sprayings, in conjunction with the earlier ones, are also necessary for the control of leaf-roller caterpillar.

In addition to the spraying treatment advocated, it is absolutely necessaiy to gather all grubby fruit from the trees and ground as soon as they appear infested, so that it may be destroyed before the grub leaves it.

(To be continued.)