Vegetable and Field Crops 



165 



BUCKWHEAT 



Blight ^*''' {Corticium vagum), causing death of plants in 

 large areas in the field, was noted in North Carolina. Leaf- 

 spot {Septocylind]-'ium rufomaculans (Pk.) P. & C.) is reported 

 as diminishing the yield in Connecticut. Powdery-mildew 

 {Erysiphe polygoni) is of slight importance. 



CRUCIFEROUS CROPS: CABBAGE, BRUSSELS SPROUTS, 

 CAULIFLOWER, COLLARD, TURNIP, KOHL-RABI, 

 KALE, RAPE, RADISH, BROCCOLI, RUTABAGA 



These crop plants are of close kinship and are subject, 

 essentially, to the same diseases. The more important of 

 these are internal parasites from the soil, hence spraying is 

 of less benefit than with 

 other crops. 



, Black-rot -^^'-'^^' ^-^' ^^^' ^^ 

 {Pseudomonas campestris 

 (Pam.) EFS.). — Not only 

 does black-rot destroy the 

 current crop, but since its 

 causal germ remains in the 

 soil, it seriously endangers, 

 if it does not quite prohibit, 

 the subsequent use of the 

 same field for susceptible 

 crops. Its damage to cab- 

 bage in a single season in 

 two counties in Wisconsin 

 was estimated at between 

 $50,000 and $60,000. A 

 large per cent of the dam- 

 age to cabbage in storage Fig. 88. — Cabbage leaf showing an 

 is also attributable to this incipient stage of black-rot. The 



disease. Cabbage, kale, f^^''' ""^''^ ""*"'-^. ^^* f"^ ^"fs/'^ 



, ,. f , , , . the veins, is progressing toward the 



rape, broccoli, kohl-rabl, base of the leaf . After Stewart and 



Brussels sprouts, collards, Harchng. 



ii 



