WORK FOR THE COMING MONTH.

New Zealand Journal of Agriculture, Volume XIII, Issue 4, 20 October 1916, Page 318

WORK FOR THE COMING MONTH.

THE ORCHARD.

J. A. CAMPBELL,

Assistant Director, Horticulture Di,vision.

The month of November marks the opening of the summer work in the orchard. To what extent this work is to be comparatively simple and plain sailing depends to a large extent on two things —firstly, the thoroughness with which the winter and early spring work has been attended to, and, secondly, the climatic conditions obtaining.

' Sucking-insects, such as red mite, woolly aphis, mussel and San Jose scale, &c., appear very, early in the season. Mussel scale hatch out . and are on the . move during the latter part of October and November. Red mite and San Jose scale in many instances commence activities with the spring of the. blossoms, ’ and increase rapidly in numbers through the summer. If left unchecked they seriously affect the health of the tree and. consequently the fruit crop. The winter application of insecticides such as oil emulsion, &c., previously recommended, reduces the extent of summer. affection and consequently the amount of summer spraying • required in respect to the insects mentioned, according to the thoroughness with which it has . been applied. It must be remembered . that the summer is not the time to undertake the eradication of such pests. Summer treatment at best is only 'a check, but in’ most instances ’it becomes a necessary work in order to minimize the damage which otherwise would result. .

The control of fungus diseases and the amount of work required during the early summer also depends very largely upon the late winter and early spring spraying. Under any circumstances such fungus diseases as black-spot, brown-rot, &c., are liable to cause trouble if the weather during the early summer is moist and muggy, but even under such conditions the danger is increased or otherwise according to the circumstances governing the earlier sprayings.

CONTROL OF DISEASES.

Codlin-moth.

Calyx-spraying to be of any value for the control of moth must be done before the calyx closes. The object of this spray is not to prevent the immediate affection of the fruit, but for the

purpose of secreting a small amount of poison within the eye of the apple, to be held there by the closing-of the calyx to guard against the entry of the grub at this point later in the season. •

Only under exceptional circumstances is the codlin-moth active in the orchard before the end of the second week in November. Therefore, when the earlier sprayings are not applied before the calyx closes and this period is now past the spray becomes practically wasted material if applied before the 10th or 12th November. From this time onward, however, spraying should be regularly and thoroughly done. The period between sprayings should not be more than three to four weeks, the former interval being in every way preferable.

It is well known that many orchardists spray much less frequently than this. Four, five, or even six weeks’ interval between sprayings is not uncommon, but in all such cases the loss of fruit is very much greater than would pay for the additional applications. Not only does this loss apply to grubby and moth-blemished fruit, but also to fruit blemished by the leaf-roller caterpillar, which in some districts- during the past season or two has become a more serious menace than the codlin-moth. For the control of moth spray with arsenate of lead at the rate of i| lb. to 2 lb. (paste) or 1 lb. to lb. ' (powder) to 50 gallons of water.

-roller Caterpillar.

As far as all practical purposes are concerned the life-history of this pest resembles that of the codlin-moth, with three important exceptions, (i.) The young grub is not entirely dependent on the fruit for food, but secures nourishment also from the foliage, and may be therefore more or less grown, and consequently more difficult to kill, where it attacks the fruit. (2.) The chrysalis stage is passed between leaves rolled or sealed together for protection, and also in the stem end of the fruit. In regard to the latter condition, fruit is often wrapped with the chrysalis still in the stem-cavity. The . rolling •of the leaves and the sealing of the leaf to the side of an apple not only affords protection for the chrysalis, but also protects the grubs in different stages of development from the effects of the spray. (3.) Unlike the codlin grub, the leaf-roller caterpillar does not necessarily confine its attention to single fruit, but may pass on from one to. another, blemishing several. Therefore fruit unblemished when packed may open up considerably damaged through a few grubs being packed within the case.

The ability of the grub to survive on the foliage would at first glance appear to afford it little advantage, as the foliage as well as the fruit of a sprayed tree is more or less coated with

the material. At the same time, apart from the fact that there is considerably more foliage than fruit on a tree, and therefore a greater percentage apt to be missed, it must be remembered that in the case of the apple the spraying of the foliage is incidental to spraying the fruit, and so long as the fruit is covered no special care is given -to the foliage unless there is a special object in view. The result, no doubt, is that sufficient food is provided in this way by the new foliage that is constantly being produced by the tree to sustain quite a large number of grubs, which later, when their strength increases and the strength of the spray decreases, may attack the fruit with impunity.

The means of reducing possible damage by the leaf-roller to a minimum necessitates frequent spraying with arsenate of lead, as recommended for the control of codlin-moth, taking care to cover the foliage as well as the fruit of the tree with the material.

Black-spot

For the control of black-spot combine lime-sulphur with the arsenate of lead when spraying for moth. Should the weather during the month be favourable to the spread of fungus diseases, extra care will require to be taken to guard against outbreaks by taking advantage of any brief spells of suitable weather for spraying. Should the disease break out and the fruit become at all badly affected, it may be necessary to' resort to 3-4-40 Bordeaux mixture as a means of checking its further spread; but this should be avoided if possible, owing to the russeting effect this spray has upon the fruit.

Brown-rot

This disease usually attacks the fruit just prior to ripening, hence the name of “ ripe-rot,” by which the disease is also known. But its attacks are by no means confined to this period; if the weather is at all wet and favourable, stone-fruits very often become affected shortly after they are set. Brown-rot affects both pip and stone fruits, but is particularly destructive in regard to the latter. Thinning has a very beneficial effect, and for this reason alone should be carried out in districts affected with the disease. As soon as the disease is noticed all affected fruit should be picked off and destroyed, and the tree sprayed with a weak solution of Bordeaux mixture, or lime-sulphur i-ioo to 1-125.

Powdery Mildew, Mussel Scale, and Red Mite.

For powdery mildew remove all affected parts, and spray with lime-sulphur combined with arsenate of lead when spraying for moth. This will also prove satisfactory in keeping in check red

mite, and will destroy the unprotected mussel scale. Strength of lime-sulphur 1-80 to i-ioo.

DISBUDDING

The formation of young trees can be greatly assisted by the rubbing - off or removal of undesirable wood-growths. This work pays very well for a little attention, and the earlier it is commenced the greater will be the advantage gained by the permanent branches through the operation.

CULTIVATION.

An abundance of rain has fallen throughout New Zealand during the last few months. This should prove very beneficial generally, but particularly so to several districts which have suffered more or less from a . limited rainfall for some considerable time. The subsoil has been well saturated, and where good drainage exists the surplus water has drained away. Such conditions are favourable to a good season, for without an adequate supply of moisture the best of soils become of little or no use. All that is required now is to cultivate the orchard in such a way as to maintain the fullest advantage of the present conditions. To do this the surface of the soil should be thoroughly worked up with the cultivator as soon as it is in a fit state, otherwise the surface will bake and crack and the loss of moisture will commence. The operation should be repeated every few weeks throughout the summer. Should this be done it will be found that fruit-trees will remain healthy and thrifty with little or no rain for the remainder of the season.