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 



