196 



VEGETABLE DISEASES ROUND TABLE 



There are several metliods of control open for consideration, 

 although some of them are not applicable to our most usual system of 

 growing onions. Rotation of crops is said to be a means of reducing 

 the amount of smut, but from what has been stated above, soil can 

 not be freed from the disease in this way. Onions grown from sets 

 and transplants are not subject to the disease. The proposition of 

 transplanting onions has been suggested in Connecticut and urged by 

 Sirrine and Stewart, but so far as the speaker has been able to deter- 

 mine, has not been practiced except in connection with the production 

 of an early crop by the market gardener. The treatment of seed has 

 not been practiced in any place. In view of the fact that the spores 

 of the fungus are carried on the seeds, it would seem highly desirable 

 to treat seed for fields in which the disease has not yet appeared. 

 Some strength of formalin would doubtless prove effective, and if 

 there were a demand for it, the exact strength could be determined 

 easily. 



Professor Thaxter tried several soil treatments, and fortunately, 

 the first year of experimentation, found certain substances quite effec- 

 tive in controlling the smut. The combination which seemed to be 

 most effective and the one which has been used most since that time 

 is a mixture of sulphur and lime. Sirrine and Stewart followed up the 

 sulphur and lime treatment in Orange County with excellent results. 

 Various quantities were tried, but after five years' experimentation, 

 they finally recommended the use of one hundred pounds of sulphur 

 and fifty pounds of air slaked lime per acre. This is to be applied in 

 drills by means of a special attachment. Broadcast applications 

 prove ineffective. It should be noted in this connection that the 

 treatment does not give perfect control. In 1898, for example, the 

 treated plats showed by actual count twenty per cent, of smutted 

 plants. The untreated plats, however, gave seventy -two per cent, 

 smutty plants. It should be noted that the treatment is more effec- 

 tive when there is a great amount of smut in the soil. Up to a certain 

 limit, one can overcome the smut difficulty by planting more seed but 

 when ninety per cent, of the plants come smutty, it becomes rather 

 expensive and practically an impossibility to plant so much seed. 



The sulphur seed drill devised by Sirrine and Stewart for the 

 Orange County growers was constructed for them by a Mr. Hoffman 

 of Florida, New York. The drill has been slightly improved since 

 then. I exhibit here the drill as made by Mr. Hoffman at the present 

 time. 



