JOm£ OF AGMCPLTIAL ffiSEARCH 



Vol. XII Washington, D. C, March 4, 191 8 No. 9 



WILT DISEASES OF OKRA AND THE VERTICILLIUM- 



WILT PROBLEM 



By C. W. Carpenter,' 



Scientific Assistant, Cotton, Truck, and Forage Crop Disease Investigations, Bureau of 



Plant Industry, United States Department of Agriculture 



INTRODUCTION 



The investigation of the okra-wilt disease thus far reported has led 

 to some confusion as to the cause of this malady. Atkinson (jY men- 

 tions the fact that okra {Abelmoschtis esculentus) is sometimes attacked 

 by a disease similar to the wilt of cotton (Gossypium herbaceum). He 

 states that a fungus for which he proposes the name "Fusarium vasin- 

 fectum" is invariably found in the vascular system of cotton and okra 

 affected with this disease. Smith (25), in a more extensive study of the 

 wilt diseases of cotton, watermelon (Citrullus vulgaris), and cowpea 

 (Vigna sinensis), found an ascigerous fungus associated with the diseased 

 plants. He regarded this new genus as the perfect form of Fusarium 

 vasinfectum Atkinson, and renamed the latter fungus "'Neocosmospora 

 vasinfecta." Smith notes the occurrence of a wilt disease of okra, and 

 regarding A^. vasinfecta remarks (p. jj) : 



It probably occvirs also on okra, although the identification is not complete, depend- 

 ing solely on the character of the symptoms, on the presence of similar macroconidea 

 and microconidia, and on the occurrence of the disease in the same localities, no cul- 

 tures or cross inoculations of the okra ftmgus having been made and no perithecial 

 fruits having been discovered. 



Doubts as to the genetic relationship of Neocosmospora vasinfecta and 

 Fusarium vasinfectum are expressed by Higgins {12), Butler (5), and 

 Wollenweber {31, 32). It appears from the inoculation and pure- 

 culture work of the latter that A^. vasinfecta Smith is to be regarded as 

 a saprophyte entirely distinct from the vascular parasite F. vasinfectum 

 Atk. 



Clinton {8, p. 268) notes the occurrence of a wilt disease of okra in 

 Connecticut which he considers as the same as that previously reported 

 by Atkinson. The wilt of okra as it occurs in North Carolina is described 



' Since the completion of these studies, the writer has been transferred to the position of Pathologist, 

 Hawaiian Agricultural Experiment Station. 

 2 Reference is made by number (italic) to "Literature cited," p. 544-346. 



Journal of Agricultural Research, Vol. XII, No. 9 



Washington, D. C. Mar. 4, 1918 



U , , KeyNo. G— IJ7 



(529) 



