THE CLUB ROOT 



143 



field, together with constant crop-rotation, are the chief 

 safeguards against the club root fungus. The only way 

 to lessen attack is to use preyentive measures ; for when 

 once the fungus has obtained a hold upon the plant, it 

 cannot be gotten rid of. It is probable that methods of 

 preventing it from attacking seedlings in the hotbed can 

 readily be found, but few definite experiments on the 

 subject seem yet to haye been made in America. Eng- 

 lish writers assert that if the soil of the seed bed be 

 treated Avith carbon-bisulphide before the seeds are 

 planted, the traces of the fungus in the soil will be de- 

 stroyed, and the seedlings escape attack. If many of 

 the seedlings in the seed bed show the disease, the whole 

 lot better be pulled up and burned, and other plants 

 obtained. The use of lime at the rate of seyenty- 

 fiye bushels to the acre, has been recommended as 

 a preyentiye, and, apparently, backed by practical 

 experience. 



Excellent accounts, in which the life-history of this 

 fungus is fully discussed, occur in the Journal of My- 

 cology (y. VII, pp. 79-88), by A. C. Eycleshymer ; in 

 Ward's Diseases of Plants ; and in Bulletin 98 of the 

 Jsew Jersey Station, in which Dr. Halstead first pub- 

 lished the illustrations appearing above. An effect yery 

 similar to club root is often produced on the roots of a 

 great yariety of plants by the little worms called 

 Nematodes. 



