FUNGICIDES 35 



carbonate is used, when the fruit has become so large that 

 the Bordeaux mixture must be discontinued. Potassium 

 sulphide is also especially efficient as a protection against 

 the powdery mildews. 



Formalin. — Formalin is a very powerful germicide 

 which came into wide use about 1889. Its interest to the 

 farmer lies chiefly in its power to prevent the potato scab^ 

 onion smut, and the various smuts of cereals. Full direc- 

 tions for its use are given under special crops. 



This substance appears on the market under two names : 

 "formalin" and "40 per cent formaldehyde." These 

 substances are absolutely identical, and since 40 per cent 

 formaldehyde is cheaper, owing to the fact that the word 

 " formalin " is protected by patent, the customer will of 

 course do well to purchase the 40 per cent formaldehyde. 



Corrosive Sublimate. 



Corrosive sublimate 1 part 



Hydrochloric acid 2 parts 



Water 1000 parts 



This is employed chiefly as a seed disinfectant particu- 

 larly for black rot of cabbage. It is intensely poisonous 

 and should be so regarded. 



Flowers of sulphur. — This substance is chiefly employed 

 as a specific for the powdery mildews. See grape, p. 164. 



Sulphur-Soda-Soap. 



Caustic soda 10 pounds 



Sulphur ........ 35 pounds 



Fish-oil soap ....... 6 pounds 



Water ........ 100 gallons 



