CHAPTER XII 



DISEASES OF COTTON 



It is estimated that the annual loss to cotton-growers 

 in the South as a result of cotton diseases varies between 

 twenty-five and thirty millions of dollars. The suscepti- 

 bility of the cotton plant to disease is influenced by sea- 

 sonal conditions, the greatest damage occurring during 

 seasons of heavy rainfall. It is also true that the preva- 

 lence of certain cotton diseases is governed largely by soil 

 type. Those diseases which cause the greatest injury to 

 the cotton crop in the south are wilt, root-rot, root-knot, 

 anthracnose, and Mosaic disease, incorrectly called 

 "rust." 



COTTON-WILT (Neocosmospora vasinfecta) 



171. Occurrence. — Cotton-wilt occurs to a greater 

 or less extent in every cotton producing state from North 

 Carolina to Texas. It is most serious in the regipns of 

 sandy soils comprising southern and eastern South Caro- 

 lina, southwestern Georgia and southeastern Alabama. It 

 is pointed out by Gilbert, of, the Bureau of Plant Industry, 

 that the available records indicate an annual loss in the 

 cotton-belt of at least $10,000,000 from cotton-wilt alone. 



172. Cause. — The cotton-wilt disease is caused by a 

 microscopic fungus which lives as a saprophyte on the 

 decaying organic matter in the soil. After entering the 

 root of a cotton plant it becomes at once a true parasite. 

 This fungus produces Various types of fruiting bodies or 



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