DISEASES OF COTTON 147 



184. Cause. This disease is caused by a mold-like 

 parasitic fungus which penetrates almost all portions of the 

 cotton plant. Recent investigations have revealed the 

 fact that in the development of anthracnose, two kinds of 

 spores are produced, namely, the conidia and the asco 

 spores. The former are produced by the millions and are 

 responsible for the pink coloring so characteristic of the 

 disease. It seems that the perfect or asco spore stage of the 

 disease has been only rarely observed. Anthracnose is 

 spread by insects or under certain conditions by the wind. 

 It is also carried in or on the seed. Spores of this fungus 

 are left in the cotton gin by badly diseased lots of cotton, 

 the result being that seed otherwise free from the disease 

 are infected. 



185. Symptoms. Usually the first visible indica- 

 tion of anthracnose is the occurrence on the bolls of minute 

 round, dull reddish spots. As these spots increase in size, 

 the spores develop and give the diseased portion a char- 

 acteristic pinkish color. In very dry weather the spores are 

 scarce and the diseased areas may have a grayish cast. 



Badly diseased bolls produce rotten and discolored lint. 

 Often they only partially open and the lint is hard to 

 gather and in many cases is left in the field. Much damage 

 is also done in cases where this disease attacks the young 

 seedlings; it often completely kills the sprouts before they 

 appear above ground or causes a " damping-off " near the 

 soil of seedlings that are from 2 to 4 inches high. The 

 pedicels of the bolls are often attacked, the result of which 

 attack is that the bolls dry up and drop off. 



186. Remedies. Experiments have indicated that 

 anthracnose is a disease that is largely preventable. Pre- 

 ventive measures involve, (1) planting only seed that is 

 free from disease, (2) crop rotation combined with fall 



