UNITED STATES DEPARTMENT OF AGRICULTURE 



JfW^^UY. 



BULLETIN No. 828 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



May 10, 1920 



BACTERIAL WILT OF CUCURBITS. 



By Frederick V. Rand, Assistant Pathologist, and Ella M. A. Enlows, formerly 

 Assistant Pathologist, Laboratory of Plant Pathology. 





CONT 



Page. 



1 



2 



16 



cucumber 

 21 



ENTS. 



Page. 

 25 







31 







34 



Relation of the wilt bacteria to 

 beetles 



Control 



Summary 



36 



41 





FORE^ 



VORD. 





The studies of the writers on bacterial wilt of cucurbits (caused by 

 Bacillus tracJieiphilus Erwin F. Smith), published in 1915 and in the 

 spring of 1916, have been continued during the past three seasons. 

 The previously published work 1 demonstrated that the striped cu- 

 cumber beetle (DiabroticavittataFah.) and also the 12-spotted cucumber 

 beetle (D.duodecimpunctataO]iv.) are the most active and probably the 

 only summer carriers of this bacterial wilt in the localities investi- 

 gated. Some evidence was given that the striped cucumber beetle 

 may be also a winter carrier. 2 It was shown that the soil had no 

 relation to the disease either as a source of early spring or of summer 

 infection. Seed from wilted plants in all oases failed to transmit the 

 disease, and all attempts at infection through the stomata gave 

 negative results. A fair degree of control was obtained by early 

 treatments with Bordeaux mixture and lead arsenate combined, and 

 it was shown that this control was related not only to the repellent 

 and insecticidal qualities of the mixture, but also to a direct bacte- 

 ricidal action upon the wilt organism. 



The present paper deals with further studies of the relation of soil 

 and insects to the distribution and control of the disease, and includes 

 also a portion of our work with the causal organism itself. 



1 Rand, F. V. Dissemination of bacterial wilt of cucurbits. (Preliminary note.) In Jour. Agr. Re- 

 search, v. 5, no. 6, p. 257-260, pi. 24. 1915. 



Rand, F. V., and Enlows, Ella M. A. Transmission and control of bacterial wilt of cucurbits. In Jour. 

 Agr. Research, v. 6, no. 11, pp. 417-434, 3 figs., pi. 53-54. 1916. 



2 Other species of Diabrotica have not been tested. 



142179°— 20— Bull. 828 1 



