88 HUMAN FACTORS IN COTTON CULTURE 



waxy. Anthracnose is caused by a fungus which produces 

 boll rot in wet weather. Root knot is a swelling of the 

 roots of the plant caused by the presence of a small ell 

 worm. The bacterial blight known as leaf spot although 

 present in most cotton fields does not seriously affect 

 upland cotton. Rust is a physiological disease of the 

 plant, caused by lack of potash and vegetable matter, 

 or by poor drainage. 16 



INSECT PESTS 



Several insect pests that prey upon the cotton plant 

 have been long known and feared. Farmers have learned 

 in the early fall to look for the "army worms" which 

 suddenly appear in great numbers, march across the 

 fields, and leave the plants bare of foliage. Their sudden 

 appearance is owing to the fact that the adult moths 

 fly from the tropic regions to deposit their eggs in the 

 Cotton Belt. As the cotton leaf worm does not attack 

 the bolls its damages are excessive only when the leaves 

 are stripped early enough in the season to affect the 

 growth of the plant. Cold weather finishes the pest until 

 the next season. Calcium arsenate is a sure poison. 



The cotton bollworm is a general feeder known for its 

 presence in sweet corn. At one time its damage to the 

 cotton crop was estimated at $8,500,000 yearly. Its rav- 

 ages are sporadic, however, and calcium arsenate is an 

 effective poison. Cutworm, plant lice, and red spiders 

 are minor insect pests. 17 



Possibly the most dangerous single enemy to the cot- 

 ton plant is the pink bollworm, first noted in Egypt in 



10 The Cotton Plant, Dept. of Agriculture Experiment Station 

 Bulletin 33, pp. 271-317. 

 17 Ibid., pp. 317-51. Also, "The Cotton Situation," pp. 352-55. 



