Family Cruciferae 195 



of the leaves. The bases of the affected foliage are 

 covered with a white weft of mycelial growth, later 

 by sclerotia. For a more extended discussion of the 

 disease see lettuce drop, p. 143. 



BLACK LEG OR FOOT ROT 

 Caused by Phoma oleracea Sacc. 



Black leg, first noticed in the United States by 

 Manns 1 in Ohio, was undoubtedly introduced here 

 from Europe. 



Symptoms. The disease is usually manifested in 

 the seed bed about two to three weeks before trans- 

 planting in the field. The trouble at first appears 

 as white elongated sunken lesions on the stem and 

 below the leaf attachment (fig. 30 f ) . Scattered over 

 the lesions are minute black specks which constitute 

 the pycnidia or fruiting sacs of the fungus (fig. 30 i 

 and j). Infected seedlings usually collapse and take 

 on a bluish color. In the field, the foliage of the 

 older but affected plants (fig. 30 h) usually take on a 

 mottled, metallic, bluish-red color at the margins, 

 and the lower outer leaves wilt. On examining such 

 plants there will always be found sunken lesions 

 (fig. 30 g) which often girdle the foot of the plant. 

 In wet weather affected plants attempt to produce 

 new roots above the infected area, which, however, 

 are never able sufficiently to support the plant. 

 Foot rot is often confused with forms of injury 

 brought about by maggots. 



1 Manns, T. P., Ohio Agr. Expt. Sta. Bui., 228: 255-297, 1911. 



