BACTERIAL SPOT OF LIMA BEAN 1 
hy W. B. Tisdale, Assistant Plant Pathologist , Florida Agricultural Experiment 
Station, and Maude Miller Williamson, formerly Instructor in Plant Pathology , 
University of Wisconsin 2 
INTRODUCTION 
During recent years lima bean plants in the vicinity of Madison, Wis., 
have been affected with a spot disease which was recognized as distinctly 
different from the blight caused by Bacterium phaseoli E. F. S. This 
disease was first noted in 1917 in several home gardens at Racine, Wis. 
In August of that year, the disease was also observed to be quite serious 
in some of the gardens at Madison. Scarcely a plant could be found free 
from the spotting and some of the plants were affected so badly that 
most of the blossoms and small pods were shedding. During the autumn 
of 1917 intensive investigations were begun which were continued during 
the winter. After this no further observations were made until the sum¬ 
mer of 1919. During 1919 the spot appeared on the first leaves, but the 
plants outgrew it and remained practically free from it throughout the 
summer. It appeared again in the spring of 1920 and continued to 
develop throughout the summer of that year but not so seriously as in 
1917. 
In June, 1921, the senior writer visited several fields of lima beans on 
Long Island but was unable to find any signs of the spot disease. The 
plants at this time, however, had only the first two leaves present, and 
the weather had been dry and hot since the seed was planted. In Sep¬ 
tember of this year both the spot disease and blight were prevalent and, in 
some cases, serious in the gardens at Madison. 
LITERATURE 
The literature up to the present time seems to give no description of the 
disease or of its causal organism, although a bacterial disease of lima 
beans having at least some characters in common with the spot disease 
has been mentioned. 
The blight attributed to Bacterium phaseoli E. F. S. has been known 
for several years (7) 3 to attack lima bean. Halstead (4), in 1892, reported 
the occurrence of a bacterial disease of both common beans and lima 
beans on the farm of a western seed company and stated that the disease 
had been known on that farm since 1886. Beach (1) described a bacterial 
disease of lima beans in New York which he suggested as being distinct 
from the one caused by B. phaseoli . Beach’s description of the disease 
is in part as follows: 
So far as noticed, these spots are never black, but often have a reddish-purple 
border inclosing an area of light red color. The spots gradually increase in size and 
develop a straw colored center of dead tissue. 
1 Accepted for publication May 2, 1923. 
a The writers wish to make grateful acknowledgment to Prof. L. R. Jones, of the University of Wisconsin, 
for helpful suggestions in the final preparation of the manuscript. 
* Reference is made by number (italic) to “Literature cited,” p. 153. 
Journal of Agricultural Research, 
Washington, D. C. 
afp 
Vol. XXV, No. 3 
July 21, 1923 
Key No. \V1s.-23 
