170 COTTON 



after cowpeas were cultivated on the land. In 

 other words the peas introduced the nematode 

 worm, and this in turn caused the cotton plant 

 to be readily attacked by the wilt fungus. And 

 more than this, the most serious attacks of the wilt 

 are found on soils known to be infected with the 

 nematode worms. 



Root Rot: Root rot is a fungus which attacks 

 other plants as well as cotton alfalfa, also apples, 

 peaches, and other trees. The disease spreads in 

 all directions through the soil. The fungus de- 

 rives its nourishment from the living substance of 

 the root, and this naturally uses up the material in 

 the tissues, and they shrink and decay. The life 

 processes in the roots are also checked, and con- 

 sequently they are unable to supply the plant with 

 necessary food and water. As a result the whole 

 plant shrinks, withers and dies. 



Some one has suggested the application of salt or 

 kerosene to the soil as a means of checking the 

 development of this disease, but as yet the efficacy 

 of this treatment has not been proved, and there is 

 likely little or no value in it. Crop rotation seems 

 to be the only method that will serve in keeping the 

 fungus in check. Specific applications are natural- 

 ly difficult to apply, even if effective. General 

 methods that involve better management and 

 provide a comfortable home for the plant, seem to 

 be the way in which effective treatment or pre- 

 vention must be directed. Crops like corn, millet, 

 wheat, and oats seem not to be affected by this dis- 

 ease, and consequently they can readily be used in 

 a system of rotation that will bring cotton on the 

 same field only once every three or four years. In 

 this way cotton will show the advantage not only 

 of crop rotation, but will improve by reason 



