DISEASES OF COTTON 



241 



often suffers from another disease, which, in appearance, 

 is very similar to the wilt. This is the well-known root 

 rot. or "dying" of cotton. The symptoms of this disease 

 also are sudden wilting followed by the death and brown- 

 ing of the whole stalk. Plants die from this disease about 

 the time that the first 

 bolls begin to open. 

 It seems to be most 

 common in the black- 

 waxy, and other stiff 

 soils. 



The method of its 

 attack is very different 

 from that of the cotton 

 wilt. Over the whole 

 root system, and par- 

 ticularly covering the 

 larger roots, are found 

 brownish yellow 

 threads, or a fuzzy 

 growth of the fungus. 

 The threads of the 

 fungus penetrate the 

 bark and even extend 

 into the wood of the roots ; the younger roots are 

 promptly killed (Fig. 163). Wilting is due to the failure 

 of the roots to furnish the usual supply of water. 



The fungus has been found on practically all varieties 

 of cotton, but methods have been discovered for lessen- 

 ing the loss. It grows best and injures cotton most 



Photo by A. B. Shear 



FIG. 163. ROOTS OF A COTTON PLANT 



ATTACKED BY ROOT ROT 



