Vegetable and Field Crops 



185 



If melons be repeatedly grown upon the same field, the 

 disease increases year by year; hence rotation should be 

 practiced, and resistant varieties should be used. A promis- 

 ing resistant variety has been reported by Blinn. Spraying 

 as recommended for cucurbits generally is effective. 



Southern-blight {Sderotium rolfsii Sacc). — A large per- 

 centage of the muskmelon and watermelon crops in the 



Fig. 101. — Muskmelon leaf spotted with downy-mildew. 

 Original. 



southernmost states is often destroyed by this disease. It is 

 particularly noticeable on fruit upon the side touching the 

 ground, first as a slight rot (ground-rot), followed by a white 

 fringe of fungous threads which soon surround the whole 

 fruit. Later sclerotia appear as smaU round bodies, dirty 

 white to dark brown. For further description and treatment, 

 see pepper. 



Angular leaf-spot ^^^' ^^^' '^^ (Pseudomonas lachrymans (S. 

 & B.). — This disease is now known in many of the eastern 



