COTTON DISEASES 



419 



389. Sore-shin, or damping off (Rhizoctonia) . The 

 fungus causing this disease penetrates the stems of the 



FIG. 184. DISEASED LEAVES, BOLL, AND STEMS OF COTTON PLANT. 



Showing several forms of bacterial blight, known on the leaves as angu- 

 lar leaf-spot ; on the stems as black arm ; and on the bolls as bacterial 

 boll-rot. 



very young cotton plants just below the surface of the soil. 

 Some of the diseased plants die, while others recover. 

 It is worse in wet weather. Any method of hastening the 

 drying of the surface soil is believed to be helpful. This 

 may sometimes be done by passing a weeder or harrow 

 across the rows after the ground has dried sufficiently to 

 permit this. The use of lime has been recommended as 

 helpful in combating a similar disease on certain other 

 crops, but its effects on cotton have not been investigated. 



