BORDEAUX SPRAYING.

Dominion, Volume 1, Issue 68, 13 December 1907, Page 2

BORDEAUX SPRAYING.

THE DAMAGE TO FRUIT AND FOLIAGE. In Now York State the Government ex-, perts have investigated the injuries''done to loaves and fruit of trees sprayed by Bordeaux mixture. In New Zealand this trouble has been always with us, and usually it has been attributed to impure materials.' > The American 1 experiments have not taken r that possibility into account. . • ■ ''' Tile genoral conclusions como to were sub;' stantiajly as follow:—Varieties of fruit trees differ in their degrees of susceptibility to Bordeaux injury. Peaches, 'apricots, and Japanese plums are tho most susceptible: and common plums, quinces, pears, and apples, tho least susceptible. The amount of injury. sustained depends on , the degree of susceptibility, tho solvent properties qf ' ■ the cell sap on' the copper hydroxide, (hp permeability of the. epidermis of the • plant;,.. and the ■subsequent weather. The injury to ■ ' tho fruit- appears as small round ■ specks, r black or. brown in colour, which later be-V como layers of dead corky cells. tho fruit becomes distorted. Apples so i ted do not keep well, and are ■ liable todecay or become • mealy on removal from" , • cold storage. The. injury to the leaves is.it • first shown by, brown spots, and later, i£. T c T . badly. injured, the leaves turn yellow and ~ fall. The tissues of apple, blossoms are par--, v, ticularly liable to injury. . The injury ; so much resembles tho damage of, arsenites, frost, fungi, mites, and-the action of drops of water, that it is often-attributed to thosecauses.' .The experiments, seemed to-. xi that; the injurious material was absorbed-by.' -. the leaf or -fruit, the discolouration usually) ■:.* beginning around tha ptonuta or pores. Early spraying and wet weatVer increased: .the in-;> juries. An excess of sulphate of copper in the mixturo also increased tho damage, and - that damage was lessened by correspondingly increasing tho quantity of lime. It is recommendo'd by the experimenters that' less sulphate'of copper should be used, and .. the copper and limp should bo in equal quantities. The spraying should be done in' dry weather, and in moderation, so as to' prevent drips. .