Fungous Diseases of Colorado Crop Plants 
19 
each spot. This disease is not very common and epidemics are 
rarely developed. 
Control .—See anthracnose of currant. 
Orange Rust.— See Raspberry, page 45. 
Anthracnose. —See Currant, page 29. 
CABBAGE. 
Club Root. —This is an uncommon disease in Colorado. It 
occurs on cabbage, radish, turnip and other members of the mus¬ 
tard family. The roots of the infected plants become greatly swol¬ 
len and contorted, usually forming a cluster of finger-like or spin¬ 
dle-shaped swellings. Wilting of the plant results, particularly on 
hot days, although in the early stages of the disease such wilted 
plants may recover at night. Later, the plant succumbs or forms 
only a small head. The organism causing the trouble is in the soil 
and first attacks the young roots. 
Control .— (i) The disease may be carried from field to field 
in the soil on the feet of horses, or on cultivators. Diseased plants 
thrown on the manure pile or compost heap may subsequently reach 
the field. Precautions should be taken to burn all affected plants. 
(2) Rotation of crops. 
(3) Destruction of weeds of the mustard group that may har¬ 
bor the fungus. 
Black Rot. -^This is a bacterial disease. Infected plants are 
dwarfed, and often one-sided. In severe cases the entire head fails 
to develop or the plant dies. A black ring, corresponding to the 
woody part of the stem, is found in cross-sections of affected stems. 
This blackened tissue often can be traced up into the head. Infec¬ 
tion takes place at the leaf margin or about insect wounds. The 
leaf veins become blackened as the disease progresses. The tissue 
between the leaf veins turns vellow and then brown. Affected 
, leaves dry up and drop prem.aturely, thereby producing an elongated 
stem covered with leaf scars. Diseased leaves pulled from the stem 
show blackened bundles in the leaf stalk. 
Control .— (i) Disinfect the seed, before sowing, in corrosive 
sublimate, i-iooo, for fifteen minutes, or in formalin, 1-200, for 
twenty minutes. 
(2) . Prepare seed-bed with manure and soil that is free from 
diseased refuse. 
(3) Crop rotation is very important. No cultivated crucifers 
or cruciferous weeds should be allowed to grow in the ground for 
four or five years after a bad attack. 
(4) Keep down insects, slugs, snails, etc., for they spread the 
• disease from plant to plant. 
