WORK FOR THE COMING MONTH.

New Zealand Journal of Agriculture, Volume XV, Issue 4, 20 October 1917, Page 221

WORK FOR THE COMING MONTH.

THE ORCHARD.

J. A. CAMPBELL,

Assistant Director, Horticulture Division

The fruitgrower is at the present time passing through the most critical period of the whole year. His prospects for the season are very largely dependent upon the climatic conditions prevailing from September to November. Such conditions not only influence the setting of fruit and the prevalence of fungus diseases, but in those localities subject to late frost the grower has additional worries, as it is quite possible that his crop may be partially if not wholly destroyed in a single night. By the time these notes appear, if the season be a normal one, the orchardist should have rounded the corner satisfactorily. In any case he should be in a position to form a fairly correct opinion of what he may expect of the season. Although bad weather is not unknown at any season of the year, from November onward the fruitgrower has very much less to fear in this respect, and can therefore. rely to a far greater extent upon his own labours proving satisfactory than is the case earlier in the season. Such labours, however, must be continued and continued thoroughly, and also as extensively as the nature of the season demands.

SPRAYS AND SPRAYING

From now onward practically every phase of summer spraying will require more or less attention, and it is always better to err on the “ more ” rather than on the “ less ” side. The principal troubles to be dealt with are, —

Fungus Diseases. — Black-spot of apple and pear ; brown-rot (par ticularly of stone-fruits) ; powdery mildew.

Sucking-insects. — Woolly aphis ; black aphis ; red mite

Chewing-insects. - moth ; .leaf-roller caterpillar; pear-slug; bronze and brown beetle, &c.

It may be well to here specify some of the spraying-compounds that are found on the market and are in more or less popular use, as in many cases considerable confusion appears to exist regarding them :

Fungicides. Bordeaux mixture soda Bordeaux or Burgundy mixture; , Professor Pickering's lime-water Bordeaux ; copper-sulphate solution ; Cooper’s Improved Bordeaux ; Lawes Antiblight ; other Bordeaux powders and pastes ; lime-sulphur ; and atomic sulphur.

Contact Sprays.— Oil emulsion ; kerosene emulsion ; Black-leaf-40 ; resin-and-soda solution whale-oil soap Vistolene ;• Katakilla; limesulphur; and atomic sulphur. ' r

Poisonous ■ Sprays. — Arsenate-of-lead paste and powder, and hellebore powder.

Standardization not yet practicable:—Fungicides.

Now, from time to time questions are asked with all seriousness and increasing frequence —more often than not in the nature of a complaint—as to why the number of sprays cannot be reduced to one selected specific for each purpose, and why cannot a more definite recommendation be given with regard to a strength that can be relied upon to do the work required of each without injury to the fruit or foliage. The reply to this, of course, is because we have not yet reached perfection in the science of spraying. No one mixture we have yet at out disposal can be relied upon to give the best results in all circumstances.

Take bordeaux, for instance. This mixture is recognized to be the very best fungicide we have, but it is very destructive on the skin of most fruits when used in the summer. Burgundy mixture is the same or worse as far as scorching is concerned, and popular opinion is against it being equal as a fungicide to the lime bordeaux ; but, as well as being a good spray for potatoes, it does not clog the pump. Its main use, however, is when suitable lime or other ready-for-use fungicide is not available. Professor Pickering’s bordeaux, in which copper sulphate and lime-water is used, is no doubt from a chemical point of view the ideal bordeaux, and as the percentage of copper sulphate is very much less than in ordinary bordeaux it is of special interest just now owing to the high cost of bluestone. Although it is being tested, not -sufficient is yet known of it from a practical point of view to warrant its use being advocated.

Sulphate-of-copper solution is a good quick-acting fungicide for winter use, but the majority of those who have tested it are not quite satisfied that it is equal to bordeaux mixture.

Cooper’s Improved bordeaux is a patent preparation introduced with the idea of providing a reliable fungicide ready for use. Lawes Antiblight is on practically the same lines. Both are useful preparations, particularly to the owners of small orchards, as they save the trouble necessary in preparing bordeaux.

Lime-sulphur and atomic sulphur, besides being fungicides, are also insecticides. As fungicides they are superior to bordeaux for such fungus diseases as powdery mildew, but fall considerably short of bordeaux for all-round purposes. For the combined purpose of fungus and insect control they fill a very' useful . place, particularly if the season is not too favourable for black-spot. This applies to lime-sulphur particularly in connection with the latter disease. Bordeaux, owing to its tendency to blemish the fruit, should not be used in the orchard in the summer unless it is absolutely necessary, but lime-sulphur, if used with care, provides a good substitute under normal conditions as a preventive for black-spot, besides being useful, as previously stated, for other fungus diseases as well as insect pests.

The foregoing, therefore, explains to a certain extent the, difficulty that exists in reducing the number of spraying-compounds to one formula. All the fungicides mentioned, although the whole of them are never included in any spraying advice given, have their uses under certain conditions. Nor is it possible throughout to definitely standardize the strengths. Every fruitgrower who has taken an interest in spray-testing will, I am sure, agree that it is very difficult

to determine which is the best ■ under'all conditions of several sprays of almost equal merit, particularly i such sprays are fungicides ; and it is almost as difficult to definitely determine the exact strength at which such sprays should be used to give the best results under all conditions without injury to fruit or foliage. There are many conditions applying, such as variety, age and state of the tree, condition and situation of the orchard, &c. ; but the greatest of all is the variation in the climatic conditions. The apparently contradictory results so often yielded render deduction. uncertain and actual proof a matter of years. And so it will continue until the ideal spray is found— is, one that will be successful under all conditions.

Contact Sprays for Sucking-insects

Of the contact sprays mentioned for use in the summer, Black-leaf-40 appears to be one of the best, particularly for woolly aphis. This specific can be combined with arsenate of lead safely and used when spraying for codlin-moth. Black-leaf is, however, an imported preparation, and, besides being somewhat dear, New Zealand supplies are limited.

Resin-soda solution is also a good late-season spray for checking woolly aphis. It is considerably cheaper than Black-leaf. However, owing to its scorching effect it cannot be recommended for use early in the season. Even when used from March onward it is apt to do some damage. The extent of such damage at this stage, however, is not likely to be of any great danger to the tree. Oil emulsions, particularly those emulsified with soap, can be used on pip-fruits at 1-40 to 1-60, and are useful for checking sucking-insects. Kerosene emulsion is a spray which is not as popular now as it was a few years ago. Considerable damage has been done by this spray when improperly emulsified, but when the emulsion is perfect it can be used as strong as 1-12 on the majority of plants in foliage. Its principal use is in the destruction of young unprotected scale. This state in the mussel scale can be looked for during the latter part of October and early in November. Vistolene and Katakilla are also patent preparations, and are both of considerable value in the destruction of aphides and other suckinginsects. The first-named has proved very efficient against black aphis on the peach.

Whale-oil soap makes a very reliable spray for red mite in the growing season, and can be used on both pip and stone fruits, but particularly the latter. At the strength recommended it can be safely applied to peach-foliage. Preparation is as follows : Warm 14 lb. whale-oil, and in another vessel dissolve 2 lb. caustic soda. Let the latter cool until it is just warm, and then slowly add the warm oil, stirring well. When cold this will set as a hard soap. Boil for about half an hour 5 lb. of this soap, 7 oz. of sulphur, and 5 oz. caustic soda, in 3 gallons of water. Make up to 40 gallons. Spray in the evening or on a dull day.

. Lime-sulphur and atomic sulphur, as before stated, are insecticides as well as fungicides, and when combined and used with arsenate of lead throughout the season they keep many soft-bodied insects such as red mite well in check, but are of little use against woolly aphis.

Sprays for Chewing-insects.

Arsenate of lead, either in the paste or powder form, is the popular remedy for the chewing-insect group. There are many brands on the market, practically the whole of which are reliable. Among the popular are Swift’s, Hemingway’s, Bluebell, Electro, Sherwin Williams’s, Rogers’s, Lawes’s, Lion, &c. For codlin-moth the paste form of lead is recommended at lb. to 2 lb. to 50 gallons of water. The powdered form is almost if not quite as strong again as the paste, and is recommended for use at about 1 lb. to 50 gallons. Codlin-moth and leafroller caterpillar, are the two most destructive of the chewing-group. The former is well known, while the latter can now well dispense with letters of introduction as far as most districts are concerned. However, with pip-fruits the remedy for leaf-roller and codlin-moth is practically the z same, as follows :

Spray thoroughly and often with arsenate of lead.. Without counting the calyx-spray the intervals between sprayings should be about three weeks, commencing not later than the second week in November. It is quite understood that many growers allow a much greater time between spraying than that given here, but they run a considerable risk in doing so, not so much perhaps of affected fruit as of blemished fruit. • However, as far as moth is concerned, no doubt the practice can be followed with a fair amount of success under favourable circumstances. These circumstances depend upon how thoroughly the moth has been kept down in the past, and upon using a stronger spray than that previously mentioned, with, of course, the additional risk of scorching, also upon the absence of heavy rains. However, the advent of the leaf-roller alters the position. The habit of this pest is slightly different to that of the codlin-moth, making its satisfactory control a matter of more frequent spraying. 'Resin solution for bronze and brown beetle is prepared as follows : Take i|lb. resin, r lb. washing-soda, and 2 gallons water ; boil until the mixture ceases to foam.

4 Hellebore powder : Although arsenate of lead at half the strength recommended for pip-fruits has largely taken the place of hellebore powder for the control of pear-slug on stone-fruits, hellebore at | oz. to a gallon of water is still popular when spraying is required before the fruit is gathered.

Summary

Finally, in connection . with spraying and spray - strengths ticularly in connection with fungicides and many of the summer insecticides- must be remembered that the margin between the destruction of the insect or disease and the damage to foliage and fruit is often very small. Spray-strengths must be worked out' in consideration of both, and this can only be done in a general way unless after a very long and exhaustive study of locality and climate, not forgetting the very many variations of climate in any one locality. Progress is being made along these lines, but no doubt it will be a long time before we shall be able to foretell definitely what will take place under all circumstances. In the meantime the sprays are here formulated as they appear to be best suited to the average conditions, and although

reliable under such conditions any spray recommended for use may be found to do more or less damage when used under conditions other than normal.

The following is a summary of the different spraying-mixtures and the strengths at which they are recommended for use for the different purposes :

Pip-fruits. — Codlin-moth and leaf-roller ; pear-slug ; bronze and brown beetle : Arsenate of lead, powder 1 lb., paste ijlb. to 2 Ib., to 50 gallons of water. For bronze and brown beetle add f gallon of resin solution.

Woolly aphis : Black-leaf-40, 1 to 800, combined with arsenate of lead.

Red mite and other sucking-insects : Black-leaf-40, 1 to 800 ; limesulphur, 1-100 to 1-120 —or atomic sulphur, 10 lb. to 100 gallons water—combined with arsenate of lead.

Powdery mildew : Lime-sulphur, 1-100 to 1-120 ; or atomic sulphur, 10 lb. to 100 gallons water.

Black-spot : Pears —bordeaux, 3-4-40 ; or lime-sulphur, 1-80 to 1-100. Apples —lime-sulphur, 1-100 to 1-120. If season unfavourable, bordeaux, 2-3-40 for tender, and 3-4-40 for hardier varieties.

Stone-fruits. — Red mite : Whale-oil soap-atomic sulphur, 8 lb. to 100 gallons water ; or Vistolene, 1 to 100.

Black aphis : Vistolene, 1 to 100.

Brown-rot : Lime-sulphur, I to 125 ; or atomic sulphur, 8 lb. to 100 gallons water. Apply about the second week in November.

THINNING.

Thinning, as every experienced fruitgrower knows, has a very , beneficial effect on the fruit crop. This work, although it has ■ the effect of improving their quality as much as that of other fruits, is not extensively practised in the case of plums owing to their low market value. Judicious thinning becomes absolutely essential, however, with the peach, nectarine, and apricot.

Stone-fruits invariably drop more or less extensively about the time the stone begins to form. Thinning is usually deferred until after this drop takes place. It should, however, be gone on with as soon after as possible, as it is the formation of the stone that places the greatest strain on the vitality of the tree. In reality this is all the tree is concerned in-the reproduction of its seed. All our various classes of fruits have been brought to their present state of perfection by a process of careful cultivation and selection, but. if left to themselves they still have a tendency to revert back. The pulp, as we know and enjoy it, is only incidental to the seed, and under stressed conditions the pulp, not the seed, is the first to suffer. Therefore, if the cultivator would have his tree produce pulp of a maximum quantity and quality he must keep it in good heart and reduce its crop to reasonable limits.

Thinning, as some one has neatly put it, is an operation which an orchardist should employ his neighbour to do for him, as the neighbour

would be more thorough in his treatment of the crop than the owner would ever find the heart to be himself, and in most cases it is thorough treatment that is required. Peaches should be thinned until at least 4m. separate the closest fruits. Only one or at the most two fruits should be left on each twig or lateral. Whether it is to be one or two depends on the strength of the growth upon which the fruit is borne.

Under average conditions thinning means the destruction of a very large, percentage of the crop, but nevertheless it pays to do it, as it’ usually means the difference between good fruit and rubbish. Other conditions being right, over two-thirds of the crop of a tree properly thinned.- should be A-grade fruit and the remainder B-grade.

There is. ano er inducement to thinning, if such were required — namely, the control of the brown-rot fungus. Although it is agreed that this fungus in the first place finds entry to the fruit by means of a puncture in the skin, there is no doubt that the disease thrives to a very much greater extent when the fruits ‘of a tree are crowded or touching. . :

DISBUDDING.

From now onward disbudding should play an important part in the shaping of young trees. This should commence as soon as the growth is sufficiently defined to allow the proper selection to be made. Disbudding is preferable in many ways to the removal of misplaced growths later in the season, particularly in the case of newly planted trees. Young trees are required to grow as strongly as possible. To what extent strong growth takes place depends largely on the class of tree and the nature of the season, &c. Under the most favourable circumstances this for the first year is rarely more than is required, while under less favourable conditions the growth runs from poor to moderate. The removal 'of growth .in the summer gives a very decided check to the tree, and therefore should not be practised unless the strength of the latter warrants it ; and, as intimated, this is the exception rather than the rule with trees the first year after planting. Therefore cutting-out should not be too freely practisedif practised at all— other than free-growing trees during the first summer after planting. However, whether a tree is growing strongly or not, it is far better if the growths that it does make are properly placed. Here is where disbudding comes in. At the time this work is done little or no check will be given to the tree, leaving the operator free to shape his tree to the best advantage, which he can do very well if he is careful in selecting the , growths suitably placed, and by checking or removing those likely to defeat his object.

CULTIVATION

Through the summer the orchard should be kept well worked. Break up the surface well every three or four weeks with the cultivator. This will prevent the weeds from flourishing, and will also help to preserve the soil-moisture, which is a very necessary thing in a dry season.