Vegetable and Field Crops 173 



Minor diseases 



Malnutrition.-"^ — Leaves, yellowish between the veins 

 and at the margins, arc thickened and brittle. The cause 

 chiefly rests in use of too much mineral fertilizer and lack of 

 humus. 



Powdery-mildew (Erysiphe) ; Damping-off (various fungi) ; 

 Ring-spot (Mycosphcerella) do but small harm. Phoma-rot, 

 Black-root (see beet) and a Macrosporium leaf-spot are 

 reported on the turnip. Pale-spot {Cercosporella albomacu- 

 lans E. & E.) is also common on leaves of turnips. An- 

 thracnose '"^•^ (Colletotrichum higginsianum Sacc.) occurs on 

 stems and pods of turnip, and is especially injurious on 

 young plants. Leaf-spot -^'^ (Pseudomonas macidicolum 

 McC.) occurs on leaves of cauliflower and cabbage. The 

 spots are brown to purplish-gray, 1-3 mm. in diameter. The 

 leaves become puckered, and when badly diseased, fall off. 



CANTALOUPE. See p. 178. 



CAPER 



White-rust (Albugo) and Powdery-mildew (Erysiphe) are 

 recorded, but do small harm. 



CARROT 



' Soft-rot "^- -"^ (Bacillus carotovorus Jones). — In Vermont 

 serious loss from rotting of carrots was reported to the Exper- 

 iment Station in 1898. Investigation by Jones showed it to 

 be due to bacteria and that numerous other crops — namely, 

 turnip, rutabaga, radish, salsify, parsnip, onion, celery, 

 hyacinth leaves, and the fruit of tomato, eggplant, and 

 pepper — were susceptible to the same disease. 



Rot begins in the field and seriously increases during stor- 

 age. The initial attack is either at the crown or root tip, 

 from which points it proceeds rapidly through the core, 

 which becomes softened and somewhat browned with a rather 

 sharp boundary between diseased and healthy tissue. 



