400 DISEASES OF ECONOMIC PLANTS 



outgrow the disease. In such plants relapses may follow, 

 showing somewhat different symptoms, among them decay 

 of the boll, and a different sequence of color changes. 



Rotation of crops should be practiced and the diseased 

 plants should be pulled and burned to check the spread of 

 the disease in the soil, and in general the recommendations 

 given under soil diseases should be followed. The ultimate 

 solution of the question must be in the employment of 

 resistant varieties. One such, a long-staple cotton, has 

 been bred up by the United States Department of Agricul- 

 ture. 



Anthracnose (Glomerella gossypii (South.) Edg.). — The 

 causal fungus of this disease was first described in 1890. 

 The disease is very destructive in some localities and pre- 

 vails throughout a large portion of the cotton belt. In cen- 

 tral Georgia it is said to destroy about 22 per cent of the 

 crop yearly, sometimes more ; while to the state as a whole 

 the loss is put at 17 per cent or approximately $14,750,000. 



It is most conspicuous upon the bolls, where it produces 

 unsightly ulcers, at first black, and later bearing a coat of 

 pink. The ulcers have dark brown to black, watery borders 

 and vary in diameter from a few millimeters to covering 

 the whole boll. When small, the spots are reddish and 

 slightly depressed. Attacks upon young bolls stop their 

 growth and induce premature ripening and imperfect open- 

 ing, or the bolls may die and decay without opening at all. 

 In such bolls the fungus is found upon the lint and seed 

 within. Upon the stems the fungus is limited mainly to 

 injured parts, leaf scars, etc.. and to very young, tender 

 plants, causing damping off. Here it is accompanied by 

 reddening and by shrinkage in longitudinal lines. This 



