Circular No. 21. 



February, 1909. 



MASSACHUSETTS AGRICULTURAL EXPERIMENT STATION. 



Amherst. 



THE CONTROL OF ONION SMUT. 

 By Georoe E. Stone. 



Onion smut has been known in Massachusetts for about forty 

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

 it in the Massachusetts State Board of Agriculture Report for 

 1869-70. 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 to the disease, any 

 method which will kill the smut spores on the seed or in the soil is 

 beneficial, and treatment of the seed and the soil has given good 

 results. 



Onion smut appears to be on the increase in the Connecticut 

 valley and other parts of the United States and in some sections 

 the growing of onions has been discontinued. Positive results have 

 been obtained by applying per acre 100 pounds sulphur thoroughly 

 mixed with 50 pounds air-slaked lime in the drills ; and ground lime 

 drilled in with a fertilzer drill at the rate of 75 to 100 bushels per 

 acre is good, but the best results have been obtained by the use of 

 formalin ; either i pound to 30 gallons of water (1 — 240) or i ounce 

 to 1 gallon of water (i — 128) may be used. Formalin can be easily 



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