abruptly truncate above, 8-spored. Spores hyaline, ellip- 

 soidal, pointed at both ends, uniseptate, 15 by 6-j microns. 



MASSEE : Text Book of Plant, Dis., p. 445. 



MaSSEE : Kezv Bulletin, 1909, p. 337. 



NECOSMOSPORA VASINFECTA, E. Smith. 

 (Wilt Disease of Cotton.) 



The disease was reported in 1900 to be widely distri- 

 buted through the Southern States of North America, 

 where the " sea island " and " upland " varieties were said 

 to be suffering severely with the pest. 



A dwarfed growth and unhealthy appearance of the 

 plants are said to be the first symptoms. Later, the leaves 

 turn yellow and shrivel at their margins. Some plants die 

 at once, while others may last through the season in an 

 unhealthy condition. If the stem of a diseased plant is 

 cut the wood will be found to be stained brown. 



The fungus occurs in the soil ; it enters the young roots, 

 penetrates to the tap root and then travels up the stem, 

 blocking the water-conducting tissues. 



The progress of the disease is slow, the time taken for 

 the plant to develop symptoms of the disease is said to be 

 at least forty days. 



The following method of treatment is recommended by 

 the U.S. Department of Agriculture : — 



All diseased plants should be removed and burned. 



Spread of the disease should be avoided by not grazing 

 cattle on an infected field and by thoroughly cleaning tools 

 which were used on an infected field before using them on 

 another field. 



A rotation of five to six years' duration should be 

 practised. 



Diseased plants should be kept out of the manure heap. 



Diagnosis : — Perithecia superficial, globose-conical, red ; 

 asci cylindrical; spores 10-12 microns diam., continuous, 

 globose or subglobose, brownish ; paraphyses present. 



The wilt disease of okra is also probably caused by this 

 fungus ; and the fungus is described in the United States of 

 America as being the cause of the wilt of water melon and 

 cow pea. 



E. F. Smith : Bull. U.S.A. Dept. of Agric, No. 17, p. 

 45, 1899. 



W. A. Orton : Bull. U.S.A. Dept. of Agnc, Division of 

 Vegetable Physiology and Pathology, No. 27, 1900. 



27 



