COTTON-GROWING MACHINERY 299 



other material for diluting it, is applied by different dusting 

 methods. 



Fall plowing, which is so destructive to boll-weevils, is also 

 very destructive to boll-worms. The pupae pass the winter in the 

 ground. By fall plowing they are turned up and destroyed by the 

 weather and by birds. In sections where fall plowing of corn 

 fields and cotton fields is commonly practiced the boll-worm is no 

 longer a serious enemy. 



Cotton Diseases. Probably the greatest cause for the attacks 

 on cotton by fungous diseases is due to a continuous growth of 

 the crop on the same fields without rotation. Cotton diseases, 

 when once introduced, may develop so rapidly as to practically 

 destroy the crop. With these diseases, as with other plant diseases, 

 prevention is more important than cure. Among the most serious 

 diseases of cotton are cotton wilt and root rot. 



Cotton wilt is caused by a fungous growth which attacks the 

 young plants through the root-hairs in the soil. It is sometimes 

 called black root, because of the change in color of the roots within. 

 The growth of the threads of fungus close the ducts in the roots 

 and stems and prevent the plant from obtaining water. The 

 growth of the young cotton plants is immediately checked; they 

 turn yellow and die. Resistant varieties or strains may be devel- 

 oped by careful selection. In fields where the disease exists 

 certain plants are sometimes found which have resisted the 

 disease. Seed should be saved from such plants. Rotation of 

 crops is the best preventive. The disease is most common in 

 the southeastern cotton states. 



Cotton root rot is chiefly confined to the western part of the 

 cotton belt and is common on the stiff black soils of Texas. The 

 fungus which causes this disease produces a whitish thread-like 

 growth on the surface of the roots. The growth also enters the 

 roots. The surface may become darker and wart-like bodies 

 often appear. As the disease lives in the soil, fall plowing is help- 

 ful. Rotation of crops will largely control the damage. Grasses 

 and small grains may be used in the rotation, as they are not 

 affected by this disease. Alfalfa and sweet potatoes are some- 

 times attacked by the same fungus and should not be used where 

 cotton root rot is known to exist. 



Cotton-growing Machinery. Cotton seeding is chiefly done 

 by planters drawn by animals. The machine resembles a one- 

 horse corn planter, and indeed is used for both purposes. A fertili- 

 zer attachment is commonly used. 



