VEGETABLE AM J) FIELD CROPS 289 



corresponding upper surfaces, indicate the downy mildew. 

 The disease in its habit and damage resembles that of the 

 grape, p. 166. 



Serious loss is reported from New Mexico and Virginia. 



Leaf blight, phyllostictose (Phylloslicia Chcnopodii Sacc). 

 — This disease affects tlie leaves, especially at their bases, 

 producing spots which bear minute i^ycnidia. 



Cercosporose ((7ercospora heticola Sacc). — This disease 

 often ruins crops by yellowing and dwarfing the plants, 

 thus rendering them worthless for market. By causing 

 local leaf spots it diminishes the vigor of the plant. 



SQUASH 



Powdery mildew {Erysiphc cichnraccarum DC.). — This 

 mildew is very common upon the sciuash, forming the usual 

 whitish coating upon the surface of the leaves and .stems. 



Downy mildew. See cucumber. 



Wilt, bacillose. Sec cantaloupe. 



Anthracnose, coUetotrichose. S(h; watermelon. 



SWEET POTATO 



Soft rot (Rliizopus nicjricanf; Ehrbg.). — The most prom- 

 inent .soft rot of the sweet i")otato, the only one that is 

 commonl}' met, may be recognized i)y the soft, wrinkled 

 condition of the potato, its sweetish odor, and usually 

 by the presence of a white, later black, growth of mold, 

 appearing through the skin of tlic rotten portion at points 

 of rupture. 



The decay mo.st often begins at on(! end and passes 

 rapidly through the root, but it may start at a wound upon 

 any part of the ])otato. It i)rogresses with such rapidity 

 u 



