Circular No. 41. 



April, 1914. 



MASSACHUSETTS AGRICULTURAL EXPERIMENT STATION. 



AMHERST. 



THE CONTROL OE ONION SMUT. 

 Bv George E. Stone. 

 Onion smut has been known in Massacliusetts 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 

 iS6g — 70. The smut germs 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 the 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 beneticial. 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 remedial measures. 



Fk;. I. Shijwiiig Planet Jr. cultivatur with fcirnudin drip. 



Positive results have been obtained by applying per acre 100 pounds 

 sulfur thoroughly mixed with 50 pounds air-slaked lime in the drills, 

 and ground lime, drilled in with a fertilizer drill, at the rate of 75 to 

 100 bushels, is also good. But by far the best results have been ob- 

 tained from the use of formalin, which may be applied at the rate of 

 one ounce to one gallon of water (i-i 28), or in even weaker solutions. 

 Some onion growers in the Connecticut valley, where the crop is 

 grown extensively and with great success, occasionally use the for- 

 malin stronger than the amounts recommended, but this results in 

 injury to the crop, i-ioo parts, which is sometimes used, is capable 

 of killing almost anything, and in our opinion is too strong to apply 

 to seed. 



