Family Cruciferae 207 



and usually occupy large areas of the leaf. At first 

 they are yellowish red in color ; but they become gray 

 with age. 



Leaf Spot 

 Caused by Cercospora armoracue Sacc. 



Leaf spot is characterized by pale spots on the 

 leaves (fig. 34). The spots are usually confined to 

 weakened leaves. The disease is of no importance. 



Control. Usually the diseases of the horseradish 

 are not serious enough to warrant treatment. How- 

 ever, when the crop is grown on a large scale, it 

 should not be planted anywhere near cabbage or 

 other cruciferous plants in order to protect it from 

 black rot. If any of the leaf spots become serious 

 the affected parts may be removed and destroyed 

 and the plants sprayed with 4-4-50 Bordeaux. 

 The plants should be carefully cultivated and 

 fertilized in order to maintain their vigor, thereby 

 also preventing the leaf diseases from getting 

 troublesome. 



DISEASES OF THE KALE (Brassica oleracea 



var. acephala) 



Kale is considered a very hardy plant ; it is, however, 

 subject to black rot, Pseudomonas campestris (Pam.) 

 Ew. Sm. On the leaves, black rot is characterized 

 by dark discoloration of the veins, and on the root, 



