Fiber Plants 345 



Several such have been bred by the United States Depart- 

 ment of Ao;riciilture. 



Anthracnose ^™- ^'^ {Glomerella gossypii (South.) Edg., 

 Colletotrichum). — The causal fungus of this disease was first 

 described in 1890. It is very destructive in some localities 

 and prevails throughout a large portion of the cotton belt 

 of the United States and in the West Indies. The estimated 

 loss for 1917 was 2.84 per cent or 364,000 bales. 



It is most conspicuous upon the bolls, where it produces 

 unsightly ulcers, at first black, and later covered with a pink 

 coating. The ulcers have dark brown to l^lack, watery bor- 

 ders and vary in diameter from a few millimeters to an area 

 involving the entire 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 

 disease upon young plants usually follows the use of dis- 

 eased seed. Upon old stems it causes blighting of the bark, 

 which becomes reddish brown and dies. 



The attack upon the leaves as upon the stems is mainly 

 limited to injured or weak parts. The seed leaves, being 

 in a state of weakness, are especially susceptible to the 

 fungus, which develops here with characters very similar 

 to those on the stem and the boll. The leaves sometimes 

 have a scalded look, assume a yellowish or leaden green 

 color, wither and die, much as though frosted. 



There is evidence that the disease is largely carried from 

 year to year in the seed and may he spread to clean seed, 

 also, in the gin. Therefore, only seed from health}^ fields and 

 seed that has been ginned only where healthy cotton has been 

 ginned should be used. 



Since the spores on the seed are short-lived, cotton seed 



