Diseases of Vegetables L335 



such conditions can be avoided but no remedy is known for out- 

 door lettuce. The only hope lies in obtaining varieties or strains 

 less subject to the disease. 



Bhizoctonia Rot [Corticium vagum B. & ('.. var. solani Burt.), 

 Fig. 392. This is a very destructive disease of outdoor lettuce in 

 this state and is of considerable importance in greenhouses. The 

 rot begins where the bottom leaves rest on the ground and gradu- 

 ally works up into the head, destroying the blades of the leaves 

 and usually leaving the midribs and stem more or less intact. 

 Under glass, care in watering, so as to keep the leaves and surface 



Fig. 391. — Cucumber White Pickle 



of the soil as dry as possible, usually holds the disease in check. 

 Outdoors little can be done towards controlling it, but thorough 

 drainage and frequent cultivation are of value. In greenhouses 

 soil sterilization, preferably by steaming, insures crops free from 

 the disease, but is out of the question for fields on account of cost. 

 Botri/tis Rot (Botri/tis cinerea Pers.). This rot is of no 

 importance outdoors but is occasionally destructive under glass. 

 Diseased parts are covered with a dirty grey fuzzy mold. The 



