JOURNAL OF Acmim RESEARCH 
Vol. XXV Washington, D. C., September 22, 1923 No. 12 
BACTERIAL LEAFSPOT OF CLOVERS 1 
By L. R. Jones, Professor of Plant Pathology, and Maude Miller Williamson, 
Instructor in Plant Pathology, University of Wisconsin; F. A. Wolf, Botanist, North 
Carolina Agricultural Experiment Station; and Lucia McCulloch, Assistant Path¬ 
ologist, Laboratory of Plant Pathology, United States Department of Agriculture 
INTRODUCTION 
A leafspot disease of red clover, Trifolium pratense, quite unlike any 
of the several well-known diseases of this crop, was first noted in clover 
fields and on wayside plants in the vicinity of Madison, Wis., in I9i6. a 
The next year the same disease was observed in the vicinity of Raleigh, 
N. C., not only on red clover but also on white clover, Trifolium repens, 
and on alsike, Trifolium hybridum , as well (PI. 1, 2). This disease has 
been found in the District of Columbia and in neighboring Virginia and 
Maryland fields on the common red and white clovers. At Arlington, 
Va., it also occurs on Trifolium repens, var. latum, Trifolium medium , 
Trifolium hybridum and Trifolium pannonicum (PI. 3). Preliminary mi¬ 
croscopic examinations made of the Wisconsin material in 1916 showed 
that the disease was probably of bacterial origin. This conclusion was 
supported by the fact that isolation then made yielded a preponderance 
of similar white, bacterial colonies. Transfers from these proved uni¬ 
formly to be pathogenic on red clover. A survey of the literature on 
clover diseases, both American and foreign, was accordingly made in 
an attempt to identify this bacterial leafspot disease. It was apparent 
from the few publications on this subject that this disease can not with 
certainty be identified as any of those previously described. Because 
of the economic importance of clover as a forage and hay crop, therefore, 
and of the lack of knowledge of this disease, independent investigations 
were undertaken at the University of Wisconsin, at the North Carolina 
Agricultural Experiment Station, and in the Laboratory of Plant 
Pathology at Washington, D. C. These have for the most part been 
prosecuted independently, with numerous interruptions at each place, 
1 Accepted for publication July 3.1933. 
* The investigations of this clover disease have been involved with those of related diseases of other 
legumes at Wisconsin and elsewhere, and acknowledgement is due to several associates aside from the 
authors. The disease on red clover was first observed by Dr. A. G. Johnson and Dr. C. S. Reddy in 1916, 
and the first isolation of the causal organism was made by Doctor Reddy. These two men and Dr. F. R. 
Jones have supplied further data on the distribution on this host. The details of the Wisconsin studies 
during 1917-18 passed into the hands of Miss Florence Coerper and were carried on in conjunction with her 
related investigations of soybean bacteriosis. In 1919 Miss Maude Miller (Mrs. Williamson) succeeded her 
in handling these details. When it was learned that Dr. F. A. Wolf in North Carolina and Miss Lucia 
McCulloch in Washington, D. C., had each independently found and studied the same disease with supple¬ 
mentary host range, it was decided to correlate the results few joint publication. The final development 
of these plans has necessitated conferences, somewhat delayed publication, and in places has encumbered 
the text with details which might otherwise have been omitted. It is, however, believed that the scientific 
worth and convenience of such correlation as compared with independent reports justifies joint publication. 
The only personal regret to me in the outcome is that the position of my own name as senior author fails 
properly to indicate the indebtedness to my younger associates for most of the details of workmanship.— 
Journal of Agricultural Research, 
Washington, D. C. 
agl 
(471) 
VolXXV, No. 1* 
Sept. 32, 1923 
Key No. Wis.-*4 
60097—23-1 
