62 FRUIT TREES AND THEIR ENEMIES 



an ordinary oil be used, the results may be less 

 satisfactory — 



9/;. Made with copper sulphate (Bordeaux 



emulsion). 

 \6d. Made with iron sulphate. 

 24/;. The same, but with potassium sulphide in 



addition. 

 16^. Made with soap. To which, also, potassium 



sulphide may be added, if required, in 



the proportions given under 24c?. 



In most cases it is immaterial which of these is 

 selected, but if fungicidal properties are required, 

 either 9/7, 24^, or 16^ with potassium sulphide, must 

 be used ; also, in dealing with aphis, the emulsion 

 made with soap (16/7) should be selected in prefer- 

 ence to the others. All these emulsions contain 

 I to 1 1 per cent, of paraffin. 



Where "arsenate" is recommended, this refers to 

 lead arsenate, made according to either y%^ ^b or 3^. 



Apples 



Woolly Aphis or American Blight. {Schizoneiira 

 lanigerd). — This pest is easily recognised owing to 

 the white cottony threads which more or less cover 

 the body of the insect, and which produce the ap- 

 pearance of patches of cotton wool on the infested 

 trees. It exhausts the trees of their sap, and, by 

 producing wounds, renders them liable to attacks 

 of canker and other fungoid diseases. In winter, 

 the insect exists (i) as a purplish-brown adult in 



