ANGULAR-LEAFSPOT OF TOBACCO, AN UNDKSCRIBED 

 BACTERIAL DISEASE^ 



By F. D. Fromme, Plant Pathologist and Bacteriologist, and T. J. M.vrs.ay,^ formerly 

 Associate Bacteriologist, Virginia Agricultural Experiment Station 



INTRODUCTION 



About the first of August, 191 7, the Virginia Experiment Station 

 received a petition from 52 tobacco growers in HaHfax County, asking 

 assistance in combating a tobacco disease which threatened serious 

 losses to the crop. Diseased tobacco plants (Nicotiana tabacum) were 

 later received from a correspondent at South Boston, the leaves of which 

 were covered with spots which were different from any previously seen 

 by us, the most distinctive feature being the irregularly angular shape. 

 Numerous motile bacteria were found in crushed tissue mounts and 

 freehand sections of spots, and the organism was readily obtained in 

 pure culture from poured plates of beef-peptone agar. The same organ- 

 ism was obtained later from material which the writers collected in the 

 field from five different places in Halifax County. 



Several inspection trips were made during the remainder of the season 

 of 1 91 7. On August 10 the disease was found on the tobacco plants 

 in most of the fields along the road between South Boston and Republican 

 Grove, a distance of 30 miles. It was found later in the northern part of 

 Halifax County, at Clarkton and other points, in the southern part of 

 Campbell County, at Brookneal and Naruna, and at Charlotte Court 

 House, in Charlotte County. Inquiries through county agents extended 

 the distribution to include Mecklenburg, Pittsylvania, Henry, and 

 Patrick Counties, involving the greater part of the flue-cured-tobacco 

 belt in Virginia. 



FIELD APPEARANCE OF THE DISEASE 



The epiphytotic was well advanced by August 10. Many fields were 

 found in which practically every plant was affected, and in some fully 

 50 per cent of the crop was estimated by the growers to be unfit for 

 harvest. Late plantings were found to be less severely spotted than 

 the early plantings, and the most forward and vigorous plants were 

 invariably more seriously affected than the less vigorous ones. 



The distribution of the spots on the plants was a distinctive feature 

 and one that readily separated them from "frogeye" (caused by Cerco- 



' Paper 53 from the Laboratory of Plant Pathology anfl Bacteriology, Virginia Agricultural Experiment 

 Station. 

 * Now Bacteriologist, Washington Agricultural Experiment Station. 



Journal of Agricultural Research, Vol. XVI, No. 8 



Washington, D. C. Feb. 24. 1919 



rj Key No. Va. (Blacksburg)-3 



(219) 



