Sept. 1894.] 



INJURIOUS INSECTS AND FUNGI. 



45 



The superior advantages of this composition have not been 

 seen in this country, but in wet seasons the molasses would 

 probably make the sulphate of copper adhere better to the 

 leaves. 



Preparation of the Compositions. 



The sulphate of copper should be pure. Ordinary commercial 

 sulphate of copper contains a large per-centage of sulphate of 

 iron, which diminishes the action of the sulphate of copper and 

 makes the composition of a dirty green colour. 



The lime must be of the best quality, well burnt and 

 unslaked. 



The sulphate of copper, roughly pounded, should be dissolved 

 in cold water in a wooden or copper vessel. A good plan is to 

 put it in a coarse canvas or sacking bag, and let this hang over 

 the side of the vessel in the water. 



The lime must be slaked with cold water in a separate vessel, 

 and the mixture, when cold, poured into the vessel containing 

 the sulphate of copper, and passed through a fine sieve to 

 exclude grit and other foreign matter. The whole should then 

 be well stirred. A bright blue liquid is the result if the solution 

 has been properly made. 



The tubs, pails, and other vessels in which sulphate of copper 

 compositions, which are poisonous, have been put must not be 

 used for feeding animals. 



Distribution. 



On small areas, distribution may be effected by knapsack 

 machines holding about 3 gallons. There are several kinds of 

 these obtainable at moderate prices. A man can spray from 

 one-third to half an acre per day with a machine of this kind. 



Upon large acreages of potatoes a horse- machine would be 

 required. With this from 8 to 12 acres can be sprayed per day. 



The quantity of dressing applied usually varies between 110 

 and 150 gallons per acre. 



Care must be observed to ensure regular distribution by 

 means of fine spray-nozzles attached to the machines, which can 

 be easily adjusted in different directions to cover evenly the 

 upper and under surfaces of the leaves. Though opinion is 

 sharply divided as to the necessity of spraying the under 

 surfaces of the leaves, it is certain that the disease is first 

 generated there, and it would seem to be even more important 

 to apply preventive measures to the under surface of the foliage 

 than to the upper surface. 



Distribution will be materially assisted by strainers fitted 

 into the machines, and by keeping the compositions constantly 

 stirred. 



If the dressing has been regularly and properly distributed, 

 the leaves above and below should when dry be covered with 

 bright blue spots. 



