206 



Diseases of Economic Plants 



much reduced by the disfiguring spot, and the loss from rot 

 induced by it is also considerable. 



Onions before they are placed in storage should be well 

 dried. Storage bins with good ventilation, so arranged 

 as to prevent all heating or sweating of the bulbs, should 

 be provided. No infected bulbs should be stored, since 

 they will carry infection to the sound bulbs. Bins that 



Fig. 109. — Black-spot on onion. Original. 



are known to be infested, i. e., which held infected onions 

 in any preceding year, should be disinfected by a thoi'ough 

 spraying with Bordeaux mixture or plain bluestone solu- 

 tion. The white varieties of onions are much less resistant 

 than the rod and yellow kinds. 



Neck-rot -''^ (Botrytis alUi Munn). — This rot is generally 

 distributed in onion sections of the United States and Europe, 

 and causes heavy losses to stored onions as well as to crops in 



