^ 68 



THE NATURE OF COTTON WILT. 



Cotton wilt sometimes called "black-root" or "blight" 

 is a diseased condition of the stem, or roots of the plant. 

 It makes its appearance frequently about the middle 

 of May, and may continue through the remainder of 

 the growing season. After a few days of hot rainy 

 weather, the effects of the disease are most noticeable. 

 The loss is greatest in wet years. 



The disease is due to a fungus (Fusarium vasinfec- 

 tum, Atk), which can live in the soil for a long time 

 on decaying vegetable matter. It is propagated by 

 means of tiny spores and other forms of fruiting bodies. 

 This particular fungus seems to attack only the cotton 

 plant. 



In 1892 Prof. George F. Atkinson, while working at 

 this Station described this disease. In 1898 Prof. 

 S. F. Earle of this Station was called to investigate an 

 outbreak of cotton wilt on the farm of Mr. James Hall 

 at Midway, Bullock County. (1) 



Symptons of Cotton Wilt. 



The fungus enters the roots and stems of the cotton 

 plant and its threads (mycelia) fill or block up the 

 water-carrying tubes, thereby cutting off or interfer- 

 ing with the supply of food elements and water from 

 the soil. The interference with the water and food 

 supply soon causes the cotton plant to wilt. 



When a cotton plant is severely attacked by this 

 fungus, its leaves may suddenly wilt without any ap- 

 parent cause and fall off, leaving only a dead stem 

 standing. Sometimes only a small part of the plant 

 dies. The remaining part may put on a new growth, 

 but it will always remain dwarfed in appearance. 

 Extent of Cotton Wilt in Alabama. 



Cotton wilt occurs in two-thirds of the counties of the 

 State. It is spreading rapidly, and it seems a matter 

 of a short time when it will have extended to all 

 sandy soils on which cotton is continuously grown. 



The disease seems severest on loose sandy soils, but 

 it may occur on any sandy soil even though it has a 

 clay subsoil. It rarely occurs on heavy clays. The 

 worst infection is usually found where the sand has 

 washed in and formed a very deep loose sandy soil. 



Wilt and root-knot are severest in that part of Ala- 



(1) Bui. 107, Alabama Experiment Station, p. 299. 



