172 Diseases of Economic Plants 



Yellows, Wilt '-'"^' -'^' -'-■' (Fusarium conglutinans Woll.). — 

 This wilt of cabbage is destructive through a large territory, 

 particularly in the Southern states, and at least as far 

 north as Minnesota. As high as 90 per cent of loss has 

 been reported. 



The chief symptom is yellowing and falling of lower leaves, 

 and eventually all of the loaves except those of the head. 

 This character may be strongly emphasized upon one side 

 of the plant or even upon one side of single leaves. Affected 

 plants are retarded in growth and often die. After death 

 abundant pink acervuli are seen. Cross section of an 

 affected stem shows the wood ring to be darker than 

 normal. 



In treatment the same methods should be followed that 

 are suggested for cabbage black-rot; especially should in- 

 fested land be avoided, and the young plants grown in healthy 

 soil. The Volga and Houser are the most resistant of the 

 older varieties. The Wisconsin Hollander is a disease re- 

 sistant variety developed by selection. 



White-rust {Albugo Candida (Pers.) Ktz.). — White-rust 

 upon radishes often causes curious malformation of the 

 flowers and pods, which become overgrown and distorted; 

 often a flower is five times its normal diameter and is color- 

 less. Chief damage is thus done to the seed crop, which 

 may be quite ruined by this attack upon the flowers. It is 

 quite general on crucifers, but really injurious only to the 

 radish. 



Burning of all infected trash is the best preventive. 



Soft-rot {Bacillus carotovorus) . (See carrot.) — This is a 

 soft, slimy, wet decay affecting any part of the plant, and 

 spreading rapidly throughout. Wounds are necessary to 

 infection. Much injury occurs in the field, but the greatest 

 loss is in storage houses. Here the temperature should be 

 kept a degree or two above freezing, and good ventilation 

 secured. Wounds should be avoided in so far as possible, 

 and the crop dried before storing. 



