FIBER PLANTS 18T 



is caused by a fungus which attacks the outside of the 

 roots, enveloping them in a web of yellowish fibers. 

 The same fungus attacks a large number of other 

 plants; no effective remedy has yet been found and 

 cultivation of cotton has been practically abandoned 

 on infected areas. ^ 



A disease known as anthracnose (^CoUetotrieuTn) 

 is common in nearly all parts of the cotton belt. 

 This fungus causes small sunken s23ots, usually sur- 

 rounded by a reddish brow^n border. It often ap- 

 pears on the young seed leaves, when they first 

 emerge from the ground; it also develops on the 

 stem, and is found with other fungi on the leaves of 

 plants affected with rust, but the principal injury it 

 causes is to the bolls. If the young bolls are badly 

 affected, they fail to open properly, but often crack 

 prematurely, thus causing the rotting of the immature 

 contents. The disease is usually worse on rich lands 

 and in wet seasons, which cause a rank, sappy growth. 

 No practical remedy is known. 



Cotton bolls are also often destroyed by a bacterial 

 disease known as boll rot. Like the anthracnose 

 this is worse in wet seasons, and on rich, moist lands. 

 This disease has not been fully studied, but is prob- 

 ably conveyed from boll to boll by the puncture of 

 insects. The only remedial measure is to plant at 

 sufficient distance to allow for a free circulation of 



1 While the above lines were in press a paper has appeared 

 (U. S. Dept. Agric, Bureau of PI. Ind., Bull. 102 : .30-42) on " The 

 Control of Texas Root-Rot of Cotton," by Shear & Mills. As the 

 result of recent experiments the authors advise very deep fall 

 plowing of infected lands and also a strict rotation with grass or 

 grain crops. 



