884 



Spraying Experiments. 



[FEB., 



a lb. of iron sulphate have been dissolved. The mixture 

 which on being stirred turns inky black, is (according to the 

 Bulletin) "apparently colloidal or somewhat gelatinous in 

 texture, and after drying on the trees turns a dark slate 

 colour. In a few days this oxidises to a reddish-brown 

 colour, which remains constant." This mixture has, appar- 

 ently, considerable fungicidal properties ; it proved not only 

 quite harmless to apple foliage, but even to have some 

 beneficial effect; the leaves of the sprayed trees became 

 darker green and hung longer on the trees; "the twigs were 

 also more stocky and the fruit-buds plumper." 



A very similar mixture is the copper-sulphide mixture. 

 This is made as above except that 2 lb. of copper sulphate 

 dissolved in 10 gallons of water are added to the self-boiled 

 lime-sulphur mixture. This mixture, although a copper- 

 containing one like Bordeaux mixture, was found to cause 

 only very slight injury to the fruit or foliage of apples. 

 When used on trees of the " Ben Davis " variety — which, as 

 mentioned above, is specially susceptible — there resulted only 

 one-sixth of the injury which was caused to the fruit when 

 Bordeaux mixture was used. The injury to the apple foliage 

 was so slight as to be scarcely noticeable. The Bulletin 

 says : " We have in the copper sulphide the least injurious 

 form of copper, and if copper is absolutely necessary for 

 ultimate success in controlling the most difficult diseases, 

 this form of spray produces the minimum amount of injury." 



In leaving the subject of the "self-boiled" lime-sulphur 

 wash, and its modifications, a word of warning must be 

 given to the commercial grower. All these washes are still 

 in the experimental stage only, and are not suitable for 

 general use on a large scale. The Bulletin above mentioned 

 says on this point: "The harmless character of the iron- 

 sulphide is believed to be pretty well shown. It will require 

 tests under severe outbreaks of fungous diseases before its 

 fungicidal powers can be properly determined however. 

 The iron-sulphide, or even the copper-sulphide, will not be 

 recommended for commercial work until further tested. They 

 should be tried, if at all, in experiments in a small way." 

 It is pointed out, further, that it has been shown that the 

 factory- or home-boiled lime-sulphur wash (which is dealt 



