Cultivation, Spraying and Grafting

New Zealand Journal of Agriculture, Volume 59, Issue 3, 15 September 1939, Page 250

Cultivation, Spraying and Grafting

Orchard Notes

TIE Winter work of pruning, attention to shelter belts, drainage and general maintenance work should be completed early so that there is no hindrance in carrying out the very essential spring operations of applying certain foundation sprays, upon which success in disease control is so dependent, and also in bringing about a good state of' cultivation. This will have the beneficial effect of warming and aerating the soil and promoting root activity in orchard trees, thus stimulating the production of healthy foliage and inducing the necessary vigour required in developing a heavy crop. The main efforts over the growing season are directed towards pest and disease control and cultivation of the orchard land. These operations are the essentials in producing the quantity of disease-free fruit. Other operations, such as fruit-thinning at the appropriate time, go a long way towards improving quality and securing uniformity in fruit size, a subject which will be discussed in later notes. Disease Control Spraying is depended on, in the main, for controlling fungous diseases and most insect pests which affect fruit and fruit trees, although other orchard operations and orchard conditions generally have an important bearing on the incidence of disease. The general health of the tree should be considered in connection with disease control, as a tree weakened through over-crop-ping, brought about by consistent light pruning or failure to prune, lack of

general attention, poor drainage, and such causes, is more liable to suffer spray injury than a tree in a reasonably vigorous state. Dense trees are difficult to spray, in addition to creating a condition favourable for the development of fungous diseases. Excessive shelter will create similar conditions. Early fruit-thinning will assist in disease control as, by breaking up fruit clusters, more complete coverage is secured and less, protection is afforded such insect pests as leaf rollers and codling moth larvae. Success in Spraying With modern spraying appliances and the use of good materials, disease control to a very high degree is now possible. Success depends on three important considerations time of application, the suitability of the material, the strength at which it is applied, and, most important of all, thoroughness in application. Early sprayings are regulated to a large extent by the stage of development of blossom buds. One should therefore study their development and be in readiness to apply a spray at the appropriate time. Materials are fairly well standardised, and growers are well protected in the purchase of materials by a system of certification of such products. Every part of a tree must be thoroughly wetted to secure complete control of any disease or pest. Equipment should be adequate for the size of the orchard. Good spraying is more likely to be achieved where the pump is of sufficient capacity to

give good volume delivery under good pressure, especially where trees are large, for otherwise the essential time required to cover every part is not likely to be given. In cases where the pump is of small capacity and pressure is low and spray volume is correspondingly low, considerably more time must be taken over the work, as the quantity of liquid applied per tree is just as important as correct dilutions of materials used. The general trend in spraying practice is to use greater dilutions of the materials employed, and to improve coverage by improvement in pump capacity and spraying equipment generally. It is better to increase the gallonage at each application rather than to attempt to secure better control by using materials, at a greater strength than recommended, as the danger of spray injury is' not so great. Spray Schedule During September the first sprays in the general spray schedule for apples and pears become due, and already in some districts on at least some varieties the first application of a fungicide may have been applied. As a first application Bordeaux mixture 5-4-50, or limesulphur 1-30, are used, according to kind and variety of fruit to be sprayed. Bordeaux mixture is a more potent fungicide, and is preferred for general use at the green-tip stage of bud development. Used at this period, when bud scales have lifted and over-wintering spores of black spot are exposed, Bordeaux

may be regarded as a cleansing spray, $ destroying over-wintering spores, thus providing some immunity from attack. ; Subsequent applications of sulphur sprays will destroy spores from various sources which may alight on fruit and foliage. Certain apple varieties not so subject to black spot but more subject to powdery mildew infection are better sprayed with lime-sulphur 1-30 * at the green-tip period. A complete spray schedule for the control of the principal pests and diseases of apples and pears is set out below, but it may require slight modification to meet special circumstances. Recommendations in connection with the use of lime-sulphur refer to commercial brands containing 15 per cent, poly-sulphides, which is practically standard. Apples (1) Green-tip Bordeaux mixture 5-4-50: or lime-sulphur 1-30. (2) Open-cluster to the Pink Period. — . Lime-sulphur 1-150, plus colloidal sulphur 2 lb. to 100 gallons of the mixture. Note: It is an advantage to weaken the lime-sulphur to summer strength at this stage and supplement with colloidal sulphur to reduce russetting. The alternative is to use lime-sulphur 1-75. (3) Petal-fall Period.— Lime sulphur 1-150, plus colloidal sulphur 2 lb. to 100 gallons, plus lead arsenate li lb. to 100 gallons, plus hydrated lime 3 lb. to 100 gallons. (4) Ten to 12 Days Later. Repeat No. 3. (5) Seventeen-day Intervals up to MidDecember. Lime-sulphur 1-180, plus colloidal sulphur 2-100, plus lead arsenate lg-100, plus hydrated lime 3-100. (6) Subsequently at 14- to 21-day Intervals until end of January and later as required on later Varieties. Lime-sulphur 1-200, plus other ingredients as in No. 5. In addition to the pests combatted by the use of lead arsenate, other pests which attack the foliage may require special treatment by contact sprays and fumigants. For instance, apple leafhopper may become troublesome if no effort is made to destroy this pest when it first appears. In some districts j under dry and warm seasonal condi- , tions it may appear in appreciable numbers by the end of October. A close observation on foliage near the base of the trees should be made from early in the season, and spraying

Apples

with nicotine sulphate 1-800 should be carried out while the insect is still in the nymph stage, following which little subsequent trouble is likely to be experienced that season. Red mite may also appear any time during the summer, and can be destroyed only by the use of summer oil. As it is difficult to apply summer oil before January without in some way interfering with the general spraying schedule for the control of fungous diseases, it is necessary to guard against an early attack if possible by destroying winter eggs where they are present in quantities by using a winter-oil spray during dormancy and then using a combination of lime-sulphur and

colloidal sulphur for the early summer months. Pears ‘ (1) Green-tip Period.— Bordeaux mixture 5-4-50. (2) Pink — Bordeaux mixture 3-4-50, or lime-sulphur 1-75. (3) Petal-fall Period. Bordeaux mixture 3-4-50, plus lead arsenate lj lb. to 100 gallons or as for apples. (4) Later at Intervals. Spray as for apples. , - Certain pear varieties will not tolerate so much Bordeaux mixture, but a smoother-skinned and more at-tractive-looking pear is produced when

the sulphur sprays are applied. However, under certain conditions it is impracticable to depart from Bordeaux mixture until later in the season, especially on such varieties as Winter Nelis. The alternate programme suits such varieties as Winter Cole and P. Barry. Josephines will not tolerate Bordeaux mixture after green tip, and they should be treated as would be recommended for the more delicate apple varieties. Bordeaux mixture 5-4-50 is prepared by using 5 lb. bluestone and 4. lb. hydrated lime of high purity to 50 gallons of water. The method of manufacture is to dissolve the bluestone and almost fully dilute with the bulk water to make up almost the required quantity of spray. The hydrated lime should then be made into a milk with a smaller quantity of water and poured into the bluestone solution while the agitator in the spray vat is running. Further .water may then be added to bring up the quantity to give the correct dilution. - Where considerable quantities of Bordeaux mixture are required it is necessary to prepare for the work by having sufficient bluestone in solution for at least a day’s requirements. A stock solution may be made by dissolving a quantity of bluestone in . a wooden barrel by suspending a known weight in water near the surface and having the liquid in the barrel measure as many gallons as pounds of bluestone used. ' Then, to measure out say 10 lb. of bluestone, it would be necessary to take 10 gallons' of the bluestone solution.

Grafting Unsuitable varieties may be changed by grafting, and the work may proceed as soon as . the bark will lift freely. It is sometimes possible to begin by mid-September, and the work may be continued well through October, so long as the scions are kept in good, fresh condition and have not made appreciable movement. Varieties for reworking should be selected from the better commercial varieties, keeping in mind the advantages gained from a good succession in affording a good distribution of labour through the harvesting season while avoiding, as far as possible, having too many small lines. For northern districts, Tasma might be recommended as a good variety for replacing Delicious, which may have certain weaknesses when grown in the northern areas. More recently, consideration has been given, to the idea of “refurnishing” mature apple and pear trees of good framework in changing the variety—an alternative to deheading and grafting to stumps of main limbs. By refurnishing, much saving of time is effected in bringing trees back into full production, although the initial expense is greater because of the greater number of scions inserted. Not more than two seasons are lost neiore refurnished trees are producing, whereas by the older method a new framework has to be formed, which normally takes up to five and six years.

Refurnishing Trees In “refurnishing,” the trees are almost skeletonised, and scions are introduced along the whole length of main limbs. Surplus limbs are cut out, and the remaining limbs are shortened slightly. Laterals and horizontal arms, suitably placed, are cut back to short stubs for grafting, while others are removed entirely. Grafts are also placed on the top of shortened leaders. In addition to grafting on to suitablyplaced laterals and horizontal . arms, additional scions may be inserted into the bark of the main limbs. This is done by the inverted “L” method, which is just a modification of rind grafting. The scion is cut wedgeshaped and a thin strip pared off one edge. An inverted “L”-shaped incision is made in the bark of the limb, the corner raised, and the scion inserted so that the pared edge lies against the vertical edge of undisturbed bark. The scion may be held in place by a tack, and should be sealed with a good grafting compound. . It is a mistake to insert scions too closely, as the tree will soon become too crowded. Scions should not be closer than 15 to 18 inches. It is sometimes found expedient to compromise between the complete refurnishing and the cutting back to stumps by heading fairly high and reworking at the top while refurnishing the lower framework. This method is less laborious, but means a reduced yield for the first two years of recropping.

—N. J. ADAMSON, District Surveyor, Nelson.