DISSEMINATION OF THE ANGULAR LEAFSPOT OF 
COTTON 
By R. C. Faulwstter, 1 
Associate Botanist and Plant Pathologist, 
South Carolina Agricultural Experiment Station 
INTRODUCTION 
A satisfactory explanation of the dissemination of many of the diseases 
of plants is lacking. The literature recognizes such agents as insects, 
wind, tools, laborers, drainage, spattering rains, etc., and yet in some 
cases one must doubt the importance attached to these by investigators. 
In other instances, particularly in the cases of bacterial diseases affecting 
the leaves, stems, flowers, and fruits, no satisfactory explanation has 
been offered. This was the status of affairs in the case of the angular 
leaf spot of cotton (Gossypium spp.) when the author began the investi¬ 
gation of this disease at the South Carolina Experiment Station. It is 
the purpose of this paper to present the data obtained during the past 
summer and to offer the conclusion reached as to its dissemination under 
the conditions existing in western South Carolina, with a suggestion of 
the possible importance of these factors in the dissemination of other 
similar diseases. 
HISTORICAL R^SUMIS 
A brief r£sumd of the literature dealing with some of the most common 
bacterial diseases follows, being presented in order that the true situation 
may be understood and that the information found there may be used 
in this discussion. 
Beach (1893) 2 and Halsted (1893) concluded that the blight of beans was 
a bacterial disease, because of the constant association of bacteria with 
the typical lesions. Halsted further stated that the disease was carried 
over in the seed. Sackett (1909, p. 21) states that— 
Rain and dew are doubtless agents in spreading the germs from one part of the 
plant to another by washing them from old lesions onto unaffected parts, 
though no evidence of this fact is given. Edgerton and Moreland (1913) 
successfully inoculated plants without wounding, and concluded that 
infection can take place through the stomata. 
Pierce (1901) successfully inoculated the fruit of the walnut with 
water suspensions of Bacterium juglandis. R. E. and C. O. Smith and 
1 The author is greatly indebted to Prof. R. A. Harper, of Columbia University, for the perusal and 
criticism of the manuscript, and to Mr. J. W. Sanders, assistant in this laboratory, for his most careful 
and untiring aid in the work. 
2 Bibliographic references in parenthesis refer to ” literature cited,” pp. 473-475. 
Journal of Agricultural Research, 
Washington, D. C. 
ho 
(457) 
Vol. VIII, No. la 
Mar. 19, 1917 
Key No. S. C.—1 
