606 INSECTS 'AFFECTING VEGETATION 



develop and occupy the centers of these spots. Climatic conditions 

 are responsible for the abundance or scarcity of these spores. If the 

 conditions have been favorable, large quantities of spores are pro- 

 duced and the pink color is very apparent, otherwise they are scarce 

 and the diseased areas have a grey cast. 



A boll which is badly diseased externally upon opening will 

 disclose rotten and badly discolored lint. The lint in partially dis- 

 eased bolls is inferior and harbors countless pink spores. The 

 greatest damage to the bolls is done before they mature. If attacked 

 near the time of maturity, the normal development is interfered with 

 and an imperfect boll partially diseased is the result. From these 

 half opened, dried bolls the lint is hard to gather and oft times is 

 never touched. The loss of cotton in this way is quite a large item. 



This fungus also attacks the stems of young plants near the 

 ground often causing death. The cotyledons are also injured by 

 the fungus which is imbedded in its tissues. Greyish or pinkish 

 spots are found on the weaker leaves. The stem may also show 

 these depressed pink or grey areas so constantly met with on 

 the bolls. 



The fungus is an active parasite able to penetrate any portion 

 of the cotton plant and cause disease. Professor Barre's investiga- 

 tions show that the fungus winters over in the seeds which, when 

 germinated in the following spring produces the disease in the seed- 

 ling or young plant. The spores also winter over in the diseased 

 stems, bolls and seed in the field. Ten months appears to be the 

 length of time they can sustain life under adverse conditions. Much 

 has yet to be learned concerning this serious pest which causes con- 

 siderable loss throughout the state every year. 



Various remedies have been tried, but our knowledge is yet too 

 incomplete to advise any definite remedy. Spraying with fungicides 

 has not proven practical, since this would have to be done when 

 bolls were open, thus spoiling the lint. As infection has been traced 

 to the seed the spray would not reach the center of infection. 

 Treating the seed with poisonous substances has not proven effective. 

 By selecting clean seed from bolls unaffected the disease can in a 

 measure be checked. (Miss. E. S. B. 140 B.) 



FLAX DISEASES. 



Flax Wilt. The plants are attacked at all ages and die early 

 or late in the stage of growth according to the time and intensity of 

 the attack. If the soil is much infected, that is to say flax sick/ 

 most of the plants are killed before they get through the surface of 

 the ground. Such areas appear in a field of flax as centers of disease, 

 which enlarge throughout the summer as new plants sicken, wilt, 

 and die down around the margins of the spots, finally giving the 

 whole field a spotted appearance. Young plants, two to five inches 

 in height, wilt suddenly, dry up and soon decay if the weather be- 

 comes moist. Older plants which are quite woody take on a sickly, 

 weak, yellowish appearance, wilt at the top, slowly die, turn brown, 

 and dry up. Nearly mature plants which are attacked, but not yet 



