Circular No. 52 (Revision of No. 41; 



March, 1915. 



MASSACHUSETTS AGRICULTURAL EXPERIMENT STATION. 



AMHERST. 



THE CONTROL OF ONION SMUT. 

 By George E. Stone. 



Onion smut has been known in Massachusetts for about forty years, 

 Mr. Benjamin P. Ware having referred to the injury caused by this 

 fungus in the Massachusetts State Board of Agriculture Report for 

 1869" — 70. The smut spores infect the seedlings at a very early stage, 

 the disease taking the form of dark-colored or sooty masses, and as 

 the onion matures the black areas of pustules may be noticed on the 

 leaves and bulbs. Since infection takes place in early stages of the 

 seedling, onion sets being immune, any method which will kill the 

 spores on the seed or in the soil must be beneficial. Where onions 

 are grown year after year on the same land the smut shows a marked 

 tendency to increase, but even here it can be controlled by the use of 

 proper preventive measures. 



Fic. I. Showing" Planet Jr. cultivator with formalin drip. 



Positive results have been obtained by applying sulfur thoroughly 

 mixed with air-slaked lime in the drills, at the rate of 100 pounds of 

 sulfur and 50 pounds of lime to the acre. Ground lime, drilled in 



