DISEASES OF COTTON 243 



has been made weak and unhealthy by unfavorable soil or 

 other surroundings, the rust fungus enters the leaves and 

 completes their destruction. Rust is largely a disease of 

 poor land, and can be prevented on some soils by adding 

 vegetable matter or potash. 



EXERCISE. Ask your parents which of these diseases occur near 

 your home. On what kinds of soil is each one worst ? If diseased 

 plants are found, examine them in the field where they grow. Do not 

 take them to school for fear of spreading the disease. 



