Diseases OF VEGETABLES 1327 
CABBAGE 
Black Rot (Pseudomonas Cam- 
pestris Erw. Smith). This disease 
is readily distinguished by the 
presence of brown or black veins 
in leaves and cross sections of leaf 
stalks and plant stems. Badly 
affected plants are stunted and 
many of the lower leaves may drop 
off. The disease originates from 
the presence of a parasitic bacte- 
rium either on the seed or in the 
soil. All danger of disease from 
seed is removed by soaking for fif- 
teen minutes in a solution of cor- 
rosive sublimate, one ounce dis- 
solved in seven gallons of water, or 
in formaldehyde, one pint to thirty 
gallons of water. Susceptible 
crops should not be grown on soil | 
where the disease has occurred | 
until a few years have elapsed. 
Cauliflower, rape, kale, turnips, 
wild mustard and other cruciferous 
plants are also susceptible. Be: eet Dies Bet 
Club Root (Plasmodiophora brassicae Wor.), Fig. 385. Un- 
sightly swellings occur on the roots of cabbage, cauliflower, tur- 
nips, radishes, shepards purse, wild mustard and other re- 
lated plants. The causal parasite lives in the soil. It is best 
controlled by rotating crops so that a susceptible crop is grown 
on a given field only every fourth to seventh year, but in the 
meantime the field must be kept free from weeds on account of the 
susceptibility of many weeds. If infested soil must be used apply 
lime at the rate of three to five tons per acre. Apply and harrow 
into the soil the fall before planting, or better, a year or two 
before. 
