FIBER PLANTS 

 COTTON 3^5 



-^^1^369 (Fusariu?n vasinfectum Atk.). — The cotton wilt, 

 now widely distributed and yearly preempting more territory, 

 is caused by a fungus that plugs the water ducts in the veins 

 of the stem and cuts off the water supply to the parts above, 

 always reducing the vigor of the plants and usually resulting 

 in speedy death. 



Soil which produces a diseased crop one year is so infested 

 with the causal fungus as to insure its reappearance in more 

 extensive areas in subsequent croppings. The destructive- 

 ness of a disease, which takes not only the crop, but in part 

 the usefulness of the soil as well, cannot be estimated. Its 

 injury can only be realized by those who have experienced its 

 effects. 



Wilt has long been known by Southern cotton planters, 

 both on cotton and okra, and is now prevalent in many sec- 

 tions of Alabama, Arkansas, North Carolina, South Carolina, 

 Georgia, Louisiana, and probably throughout the whole 

 cotton belt. Many foreign countries also record it. Loss in 

 Georgia was estimated as SI, 000,000 annually, prior to the 

 use of resistant varieties. 



The first indication of wilt appears as a yellowing of the 

 lower leaves at the edges or between the main ribs, which 

 portions may become almost white; later they turn brown 

 and die. A single leaf often presents the three conditions, 

 green (healthy), yellow (sick), and brown (dead), in bands 

 side by side, parallel to the main ribs and radiating from 

 the leaf stem. The dead parts may break away, leaving the 

 leaf ragged. The upper leaves rapidly follow the course of the 

 lower leaves. Badly affected leaves fall away, leaving only a 

 bare stalk. In mild cases, where the disease runs its course 

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