Seasonal Orchard Notes

Manawatu Times, Volume 61, Issue 279, 25 November 1936, Page 3

Seasonal Orchard Notes

(By J. W. Whelan, Orchard Instructor, Department of Agriculture, P.N.) seasonal Spraying of Apple and Pear. Tho combination spray recommended in provious notes for control of blackspot, powdery-mildew and codlin moth, up to mid-December, should after that period be substituted for tho following: Lime-sulphur (polysulphide content of which is 15), li fluid ounces; colloidal sulphur, If ozs.; arsenate of lead (avoirdupois) loz; water, 4 gallons. In preparing this mixture the limesulphur solution should be mixed with tho required quantity of water (4 gallons).

To the required quantity of arsenatelead (loz) add three times its weight of hydrated lime (4ozs), mix with water to form a thin paste and pour into the lime-sulphur solution. Add the required quantity of colloidal sulphur (lfozs) to the lime-sulphur-lead-arsenate mixture, stir well and apply as soon as possible. The addition of hydrated lime to lead arsenate and mixed as above will eliminate the possibility of spray damage. Continue applications according to climatic conditions. Under normal circumstances from 14 to 21 day intervals should suffice. In those districts, however, subject to fogs or heavy dews or should showery to wet days set in, the period between sprays should be reduced accordngly. The safest method is to keep a close watch out for disease infection and when observed immediate steps should be taken to prevent the Infection spreading by.the application of extra sprays. In tho case of blackspot the first indication of its appearance may be observed on the underside of the leaf about the first week in November, the exact time varying with the blossoming time of the host variety. The spots, though few at first, if left unsprayed may increase in numbers and grow outwards until their margins meet, so that ultimately nearly the whole leaf surface may bo involved. On fruits, the disease makes its appearance soon after they have set, when it shows on the calyx and pedicels. The result of infection on pedicels may result in loss of crop, while calyx infection results in distorted fruits. When infection occurs on actively developing fruits the spots become sunken and as a result large cracks are formed, thus an opening is left for the entry of fruit-rolling fungi. It is possible that many orchardists do not realise the fact that black-spot is the most serious apple disease with which they have to contend, a severe attack of which may easily lead to a total loss of tho season’s crop. This may be brought about by fruit falling to the ground while in the embryo stage, or later, or by tne fruits becoming so distorted, scabbed and cracked as to be not only unsaleable but its keeping qualities so impaired as to be useless for that purpose. The foregoing should go far to prove the value of consistent spraying with the correct mixture at the correct time, for it is by he careful mixing and application of spray mixtures that not only blackspot, but practically all other fungous diseases and pests are kept under control. Eor the control of brown-rot, shothole fungous, and leaf rust on stone fruits, apply lime-sulphur li fluid ozs, colloidal sulphur liozs, water 4 gallons. This mixture should be applied every 18 to 21 days until five weeks prior to anticipated picking. Should black or green aphis appear, apply summer oil 1 fluid oz. to 4 gallons water. For control of leaf-roller caterpillar on plums and cherries, apply foz (bare) arsenato of lead, plus lioz hydrated lime to 4 gallons water. Peaches, nectarnes and apricots will not tolerate arsenates, therefore to control leafroller caterpillar on such trees apply one or two applications of summer oil, 1 fluid oz. to ,4 gallons water.