28 U. S. DEPARTMENT OF AGRICULTURE. 



Beet scab closely resembles potato scab. Large corky 

 brown excrescences are produced. Sugar beets and mangels 

 are susceptible. 



This disease is uncommon in the market. 



BRUSSELS SPROUTS: BLACK LEAF SPOT. 



(See Cabbage Black Leaf Spot) . 



BRUSSELS SPROUTS: RING-SPOT. 



(See Cauliflower Ring-Spot). 



CABBAGE: BLACK LEAF SPOT. 



Cause: A fungus (Alternaria brassicae). 



In the early stages, this disease is characterized by 

 minute, circular, shiny, brown to black spots. Later these 

 spots enlarge and lose their circular shape. The lesions 

 generally are somewhat concentrically marked in target 

 fashion and, under moist conditions, may be covered by a 

 growth of brown to black mold. Generally, if affected heads 

 are kept in a dry place, the centers of the spots fall out and 

 leave holes. 



The lesions are more pronounced and more common on 

 the outer leaves, but under moist conditions, the fungus may 

 penetrate from leaf to leaf and often may afford points of 

 attack for the bacteria of slimy soft rot. 



Infection occurs in the field, and the disease develops in 

 transit and storage. 



Disinfection of storage houses, care in handling, and a 

 regulation of temperature and moisture conditions will con- 

 trol the disease in storage. The spots do not render cabbage 

 unfit for transit and storage if the affected leaves are 

 trimmed off. 



Ref. (26). 



CABBAGE: BLACK ROT. 



Cause: Bacteria (Pseudomonas campestris). 



Black rot is characterized by a black discoloration of the 

 water-conducting tissue of the plant. Sometimes the dis- 

 coloration occurs only as a ring in the stalk, but not infre- 

 quently it extends into the leaf midrib and veins. This 

 discoloration in the stalk can be seen easily if a fresh section 

 is cut, and its progress into the leaves can be noted by break- 

 ing the leaves from the stem, which will reveal a group of 

 black dots in the leaf scars. Badly affected leaves have a 

 steel gray or purplish hue, due to partial masking of the 

 blackened veins by the white or yellowish leaf tissue. 



If no secondary rots set in, the disease may show itself 

 as a slowly progressing rot which does not necessarily pro- 

 ceed from the outside leaves as in slimy or watery soft rot, 

 but may appear in the covered leaves, even in the heart of 

 the head. Generally, however, a typical slimy soft rot sets 



