DISEASES OF CROPS 



217 



Treatment. Use nothing but absolutely clean soil in the seed-beds; 

 use lime in the fields; rotate crops. 



CANTALOUPES AND MELONS 



Leaf Blight (Alternaria brassiaz [Berk.], Sacc. var. nigrescens, Pegl.). 

 This disease starts as small brown spots with concentric rings, which 



enlarge, unite and fre- 

 quently cause the de- 

 struction of the entire 

 leaf. The melons ripen 

 prematurely and are 

 soft, wilted and in- 

 sipid. 



Treatment. Ro- 

 tate crops and spray 

 with Bordeaux mix- 

 ture. 



Downy Mildew. 

 See Cucumber. 



Anthracnose (Col- 

 Ictotrichum lagenarium 

 [Pass.], Ell. and Halst.). 

 This disease attacks 

 all parts of the vines of 

 cucumber and squash, 

 but is most injurious 

 to watermelons, causing 

 the buds and tendrils 

 to die and turn black 

 and the leaves to turn 

 yellow. It is very no- 

 ticeable on the fruit, 

 causing sunken canker- 

 like spots with pinkish 

 centers. When the 

 young fruit is attacked 

 it is likely to have a 

 bitter flavor. 



Treatment. Spray with Bordeaux mixture. 



Wilt (Bacillus tracheiphilus, E. F. Smith). This disease of melons and 

 cucumbers, and sometimes of pumpkins and squash, may start with the 

 central stem, causing the entire vine to wilt and die quickly, or it may start 

 with a branch and work slowly back to the central stem. 



Treatment. Rotation of crops; avoid those that are susceptible. 



i From Fanneis! Bulletin 488, U. S. Dept. of Agriculture. 



ENLARGED ROOTS OP CAULIFLOWER CAUSED BY THE 

 CLUB-ROOT ORGANISM l 



