VITICULTURE.

New Zealand Journal of Agriculture, Volume XXIII, Issue 4, 20 October 1921, Page 244

VITICULTURE.

J. C. WOODFIN,

Vine and Wine Instructor.

:/ THE VINEHOUSE. -. •••• There are found to be a good many variations in the manner of planting and training grape-vines, a number of which are not . in accordance with orthodox methods. In some cases the variation is inadvertent, in others intentional. Those who grow for market prefer comparatively small bunches, these being easier to weigh out. This is accomplished either by - leaving two or more bunches on each lateral, or by having the rods closer together than is. usual in the case of private growers. The latter . may be effected either by • duplicating rods or by close planting. The ’general rule is to retain only one lateral to each spur, but some growers retain two, and, of course, crop both. This is only possible where, the vines are kept well down . from the glass and the rods a fair distance apart. In these notes general principles only can be dealt with, and the methods recommended " are those suitable for ordinary growers ; experts know how to vary.the usual practice to suit their own requirements. .. : I' A/

It has already been stated that the laterals should be stopped - two. leaves beyond the bunch of fruit to be retained. It seems necessary to say that this rule is not invariable. , Thus it may be advisable to stop at one leaf beyond the bunch, as is the case when the rods are less than 3 ft. apart. Subsequent breaks are stopped beyond the first leaf in every case. ' Other breaks, termed “sublaterals,” occur from the sides of the laterals and grow up towards the glass. It is important that there be room for a free current of air to pass between the canopy of foliage and the glass. The main leaves are those of greatest value ; possibly those on sublaterals may have little or no value. In any case the latter . must not be allowed to choke the space between the vines and. the glass, or to shade the main leaves to any extent. The sublaterals should therefore be stopped beyond the first leaf, or, if they tend to crowd, be removed altogether. The sublaterals immediately above a bunch of fruit and those nearer the ends of the laterals are of greater value than those occurring between the bunch and the rod. The one that occurs close to . the junction of rod and lateral should be saved. THE VINEYARD. . , . ' At this period it is advisable to undertake control measures for powdery mildew or oidium, one of the most troublesome of grape-vine diseases. It affects the.green and tender foliage, and fruit. The young leaves show whitish or. greenishwhite patches on the upper and lower surfaces, a mottled appearance being thus produced. Later, these patches run together until a large portion of the leaf is covered with what appears to the naked eye to be a whitish powder ; hence its name. Eventually black pimple-like fruit-bodies of the fungus are seen scattered over the affected area. The diseased foliage has a wilted and dwarfed appearance, and the skin of the grapes becomes hardened, in severe cases causing the berries to burst and dry up. Powdery mildew winters in the buds, and if it develops early assisted by moist weather, which is favourable to its growth, may prevent the blossoms from setting. Grapes which have been attacked by powdery mildew, if. used for wine, give it a disagreeable mouldy taste and diminish its keepingqualities. ... ■. - . . . Winter treatment which is effective, for the prevention of black-spot is useless when applied for, oidium. Sulphur is the ■.best remedy, and is applied in a dry form by. means of sulphur-bellows, or, where a large number of vines is to be treated, with a Vermorel sulphurator. The sulphur should be as fine as possible ; precipitated sulphur is therefore preferable to ground or sublimed sulphur. Good results are also obtained ■ with atomic-sulphur spray, at the rate of 12 lb. to 100 gallons. The best time tp apply sulphur to the vines is in calm weather, preferably in the morning when the dew is still on the leaves. The presence of dew is not essential, though it causes the sulphur to adhere better. The fungicidal properties of sulphur reside, in the fumes, given off when the temperature rises above ■ 70° F. It has been noticed that sulphur-dusted vines show less tendency to drop their blossoms, and also ripen their fruit seven to ten days earlier than they otherwise w0u1d...-. The sulphur should be applied soon after the first leaves open, again during or-Just after blossoming, and again a fortnight later. Further applications are sometimes necessary on -very susceptible .varieties. . Where it is necessary to treat for black-spot, summer-strength bordeaux will be found . suitable for powdery mildew -also.. Liquid fungicides, however, are not as ■ effective as sulphur-dust, and in vineyards where this disease is particularly troublesome together with other diseases it. is better to follow bordeaux spraying with sulphur-dust. . : = ■ ■ 'Lu -