THE ORCHARD.

New Zealand Journal of Agriculture, Volume 43, Issue 4, 20 October 1931, Page 292

THE ORCHARD.

Disease and Pest Control.

The unsatisfactory results obtained from some of the commoner washes,the high cost of material, and the additional labour required for the everincreasing number of applications now being made for the control of orchard pests and diseases has caused considerable activity on the part of our research workers and others interested in commercial fruitgrowing. The ultimate goal is to increase effectiveness at reduced cost in material and number of applications to find out the strongest at which the material can be applied without injuring the tree or the greatest number of appli-s cations which the tree will withstand, but the weakest dilution at which a particular spray can be successfully applied and with the fewest number of applications. As a result, it might well be said that our spray schedules are at present in a state of flux. In the meantime, therefore, growers who feel that they have a safe and effective programme would be well advised, at any rate this season, not to drastically depart from, past practice, at the same time keeping in contact with those who are in close touch with the new movement.

It is regrettable that reference so often has to be made to the lack of thoroughness in the application of sprays, even among a number of our better growers. In the control of red mite, for instance, a very few patches, the size of the end of a lead pencil or less, scattered over a tree leave many points for fresh infection, and the tree is very soon again covered with the pest. In spraying, one is liable at each application to drive the team of the portable sprayer or work the hose of the stationary plant in the same direction, .doing the same tree first and commencing on identically the same spot on that tree. If a portion is missed the first time it is liable to be again missed on subsequent occasions. An endeavour should be made to avoid this by taking a different direction with each application, such as starting at the top of the row on one occasion and at the bottom on the next, or, with the stationary plant, working round one way at the first application and reversing it on the second.

Pip Fruits.

When these notes, reach growers in the earlier districts the calyx spray for codlin moth will have been applied or will be in the course of application. In later districts early November should, see this operation completed. Some growers, especially in Otago, have not yet realized the necessity for this spray, and often delay it until the eye of the young forming fruit is closed. In Otago the delay may be safe in some seasons, but a season occasionally occurs which upsets all calculations, with disastrous results. Moreover, seldom is it unnecessary to apply a spray at this period for other pests and diseases ; indeed, it is generally necessary to apply it as soon after blossoming as possible so as to lessen the time which has elapsed since the pink spray. The addition of arsenate of lead, therefore, is a very small item, and will act as an insurance.

With the calyx spray of i-g-lb. powder arsenate of lead per 100 gallons of water for the control of codlin moth may be combined other insecticides and fungicides. If control of leaf-hopper is necessary include 1 pint of Black Leaf 40. Bordeaux mixture, 3-4-50 (34-2-50 if hydrated lime is used), or lime-sulphur, 1 in 120 to 170 according to the strength (sulphide sulphur content) of the material purchased, will be necessary if blackspot is troublesome ; of the two, lime-sulphur is preferable on varieties subject to russet, or if either powdery mildew or red mite is a factor.

Later sprays will probably consist of applications of arsenate of lead, 14 lb. per 100 gallons water, lime-sulphur, 1 in 120 to 170, and a finely divided sulphur, 2 to 5 lb. per 100 gallons, according to the article used. It will be necessary to make these applications at intervals of ten days to three weeks according to locality and necessity. By including spreader at the rate of | lb. to f lb. per 100 gallons in each application efficiency is greatly increased. The addition of 4 lb. to 6 lb. of hydrated lime to the 100 gallons of wash will considerably reduce any liability to burning of the foliage.

. In the event of red-mite infection becoming serious the addition of f gallon of winter oil to 100 gallons of the mixture will prove very effective. The use of “ summer ” or so-called “ white ” oils, although effective against red-mite, must be restricted to applications at such times when there is no residue of sulphur or lime-sulphur on the trees, and neither of the latter should be applied for some weeks after the trees have received an application of a summer oil.

For fireblight control the advice given in last month’s Journal should be followed.

Stone- Fruits.

For the control of brown-rot and other fungi lime-sulphur, 1 in 120 to 170 (according to strength), will probably have been applied at petalfall. Another application is advisable as soon as the calyces have fallen

from the young forming fruit. When peach-green aphis first makes its appearance add Black Leaf 40, lin 800, to the lime-sulphur. As nicotine sulphate, the destroying agent in Black Leaf 40 is in itself inert, it requires such substances as arsenate of lead, bordeaux, lime-sulphur, or soap to liberate the nicotine which is the actual killing agent; therefore, if it is to be used alone, add 2to 4 lb. of soap per 100 gallons of wash. The effectiveness of nicotine lies in its volatility, and as it becomes more volatile with increasing heat more effective work is done with this spray in hot weather.

Leech on Cherries, Plums, and Young Pear-trees.

With the first appearance of leech eggs on the leaves an application of arsenate of lead, lb., and spreader, |to f lb., per 100 gallons of water should be made. At this time the fruit is not far advanced, and is not likely to have its appearance spoiled by the spray, especially if a spreader is used. This spray gives a good coating to the earlier developed leaves, which will remain for a considerable time. Through the maturing and picking season a spray on a still day directed not at the tree but upwards in the air above it, so that it will fall like a mist on the tree, will afford additional protection to the older leaves, also some will fall on many of the young leaves, while very little will be deposited on the fruit. The leech grub does not remain on one portion of the leaf or even on the one leaf, but travels to a number, and is liable to be poisoned before it has moved very far. Much injury has been done to cherry-trees by neglecting the control of leech during the season when the fruit is on the trees, and considerable protection of the foliage has been achieved with a very light mist in the manner described without disfigurement to the fruit.

Earwigs.

In districts where this pest is troublesome the banding of the trunks of stone-fruit trees with one of the sticky tanglefoot substances now on the market should be immediately undertaken. If, during the season the substance becomes ineffective through dust forming on the surface, rake it through with a stick or apply a little more. For this protection to be effective the trees must be free of herbage around the trunk, otherwise the earwigs will use a stem of grass. or weed to bridge the banding. Baits poisoned with sodium fluoride have been found very effective in reducing this pest.

Cultivation.

Where the soil has been worked down to a good tilth harrowing, with an occasional heavier working. with cultivator and disks, especially after heavy rain or irrigation, will be the main operation in this branch of operation. Where difficulty has been experienced earlier in the spring in obtaining efficient pulverization of the soil, the opportunity should be taken when clods have been softened by rain. Every effort should be made to conserve the moisture in the soil by regular and intelligent working with the most suitable implement at the time, so that the top soil is friable, devoid of lumps, and has an even surface but without a crust, so that the smallest surface possible is exposed to drying winds, and yet leaving it in such a condition that the air.can percolate through. Such a condition of soil will materially assist the action of the bacteria in changing the unavailable plant-food already in the soil and that supplied by manures into a form in which the trees can absorb it, thus assisting growth, increasing the leafsurface, and, in consequence, improving the quality of the crop generally.

Those in the South who have sown.a cover-crop of red .clover should keep mowing it from time to time as required and leave it on the surface to rot. In this way the soil is not robbed, and a great increase in humus and nitrogen will be available for turning under in one or two years’ time.

Irrigation.

Outside Central Otago systematic irrigation is only practised by a few isolated growers. Anything from four to eight applications of water are made during the season in that district. There is little doubt that in some other districts in different parts of the Dominion, notably in Marlborough and on the east coast of the North Island, considerable benefit would accrue in some seasons were cheap water available for, say, one or at most two irrigations during mid or late summer. Where irrigation is practised in this country the most suitable method is running the water with the least possible fall in not less than four but preferably six furrows in each bay. Actual details must be determined by the quantity of water and the length of time for which it is available on each application, but slowly trickling water, in small quantities in many furrows over a longer period is usually more desirable than a fast-running stream in two furrows for a short period. It is wise to irrigate early in the season when there is sufficient water supply available, as, in its somewhat moister condition at this season of the year, the soil will absorb the water to a greater depth, thereby creating a reserve, so that future irrigations, at not too infrequent intervals, would not need to be so heavy. It is always unwise to. wait until the trees are actually in need of water. Orchards temporarily sown down to clover or with a growth of weeds will require more water than those under clean cultivation (other things being equal), owing to the considerable evaporation of water through the leaves of the cover-crop in addition to that from the foliage of the fruit-trees.

Grafts and Buds.

Trees that have been worked over either by budding last autumn or grafting this spring, must receive constant attention. Almost daily visits are necessary for a while to see that no openings have been caused by the growth of the scion. Many a graft has been saved from an early death by pushing over the cracks a little of the surplus wax which is almost always to be found around the working, thus excluding the air from the union. Where there have been misses, healthy shoots should be encouraged to grow from the stock by protecting them from overgrowth of undesirable shoots ; the former can then be budded in the autumn to fill up the gaps with very little loss of time. Remove as few as possible of the shoots coming from the stock, but control them by shortening. back ; they will assist very materially in keeping vigour in a tree that has already been so severely dealt with by heading back for reworking.

Thinning the Fruit.

The thinning of all stone and pip fruit, especially peaches, nectarines, apricots, and apples, is now recognized as essential to the proper maturing of a good-quality crop. In Central Otago it is-a regular orchard practice with practically all stone and pip fruits, its neglect being looked upon just as severely as the omission of pruning or spraying. Much will depend on the vigour of the tree and the surrounding circumstances as to the extent of thinning necessary, but it is good practice to thin heavily on poorly growing trees leaving more fruit to mature on the more vigorous ones. In these times only high-quality fruit is likely to command good prices, especially in the case of stone fruit. Eliminate, therefore, poor and marked fruits, and any surplus above which it is considered the tree can mature to a good size and grade. To get the best results thinning should be done early— is, as soon as the early drop is over. In districts where late spring frosts occur it may be well to thin twice, merely singling the fruits as early as' possible at the first thinning, and giving a final one when danger from frost is over.

Miscellaneous.

There are many odd jobs requiring attention which may not have been completed during the winter. Every spare moment should be concentrated on these, so that everything is in readiness when the crop is ready for gathering. The making of cases, and the repair of stone-fruit crates where such are used, should be pushed on. The dipping of trays and crates in a bluestone solution, i lb. in 50 gallons of water, is a wise precaution against transit rots. The packing-shed, including such important machinery as the grader, nailing-down press, &c., should as opportunity offers receive a thorough overhaul and cleaning, instead of being left until they are actually required.

—W. R. Lloyd Williams, Orchard Instructor, Alexandra

Citrus Culture.

At this period of the year growers should endeavour to attend to cultivation. The ground around the trees should be worked up fine, and care should be taken not to damage the feeding roots. When the main blossoming of lemons is finished and the young fruit is showing it is advisable to spray with bordeaux, 4-4-40,. for the control of verrucosis. This disease if not controlled will produce a rough scabbed condition on the surface of the fruits, thus reducing the value. All ripening fruit should be picked as soon as ready say, at 2| in. diameter, so as to allow the development of the new season’s crop. Such fruit if left to ripen on the trees becomes large and coarse, with, a thick skin and practically no juice content, and the fruit is of little value. Any sickly trees should be carefully examined for collar-rot and other diseases. An oil spray, followed by an application of nitrate of soda, will stimulate growth. Banking up of soil around the trunks of the trees should be avoided, as it tends to hold the moisture which assists the progress of collar-rot. Young borers will now be active, and can be located by their fresh castings. The most satisfactory method for the control of this pest is to inject benzine into the holes and plug them with soap. When the young growth commences a watch should be kept for red scale and thrips. As soon as they appear an application of red oil should be applied at strength 1 in 40 to 1 in 60, depending upon the vigour and health of the tree. Where trees are more or less debilitated the application made should be weaker than that applied to trees in a more vigorous and healthy condition. Budding may be done during October or early in November, or deferred until the bark lifts freely in the autumn. If the work is done in the spring the shoots may be headed back to the bud by Christmas-time, and a good growth produced by the autumn, but the latter shoots will stand over and can be headed back in the following spring.

-L. Paynter,

Orchard Instructor, Auckland.