200 



VEGETABLE DISEASES ROUND TABLE 



different proposition altogether. That, it seems to me, is a matter 

 that needs serious consideration, and where the muck lands are as 

 localized as they are, for the most part, in this state, a precooling 

 plant in the heart of the district would be well worth while, so that the 

 temperature of the stock might be brought down to thirty -five or six 

 before it started. Then the ice would have a chance to keep the 

 temperature down. 



THE LETTUCE DROP 



We have not had any success in fighting this disease, which is 

 caused by the same Sclerotinia that attacks celery, nor the stump rot — 

 stem rot — caused by a fungus by the name of Rhizoctoma. A great 

 many different kinds of soil treatments were carried out last summer. 

 The use of sulphur, the use of sulphur-lime mixtures, the use of 

 formalin, and various methods of soil sterilizing were employed, but 

 none of them gave satisfactory results. About ninety per cent of the 

 lettuce in our experimental plats went down with one or the other of 

 these diseases. In the greenhouse, the lettuce drop — either of these 

 fungi may be responsible for drop — can be handled satisfactorily by 

 sterilizing the soil with steam, providing, of course, the seedling plants 

 are free from disease. That can usually be obtained by steaming the 

 soil in the seed bed. Apparently neither of the diseases is carried by 

 means of the seed. In fact, there is little opportunity for that, 

 because neither produce spores except under unusual conditions. I 

 should be glad to explain more about the steaming of greenhouse soil 

 if anyone desires it. 



Question : May I ask if the sterilizing is of more benefit to some 

 soils than to others? 



Dr. Reddick : I think likely. 



A Member : M^^ soil is a clay loam, and the crops did not do well 

 at all after sterilizing. 



Mr. Cook: Do you think that pink rot is the same that attacks 

 the root of the celery in storage? 



Dr. Reddick: No, I believe that is a different disease. I think 

 that is the Rhizoctoma disease. Do any of you have mildew on the 

 lettuce leaves? 



Mr. Wrigley: A little. We use the sulphur vapor. I have one 

 house which would drip more or less in wet weather, and it is pretty 

 hard work to keep it down. 



