152 
Journal of Agricultural Research 
Vol. XXV, No. 3 
at once suggests itself. However, many of the seed lima beans purchased 
on the market have cracked seed coats and will not withstand treatment 
with mercuric bichlorid or formaldehyde solutions of sufficient concen¬ 
tration and duration to kill the bacteria harbored in the tissues. Seeds 
with unbroken testa will withstand only a mild treatment with water 
solutions without injury because the testa wrinkles and breaks when 
wet. Since only a small quantity of seed known to be infected was avail¬ 
able, no tests were made to determine an effective method of seed treat¬ 
ment. Observations made in small gardens and inoculation experiments 
have shown no indication of resistant varieties. These observations, 
however, have been made on too small a scale to draw any definite con¬ 
clusions. If the disease should become serious in sections where lima 
beans are grown on a commercial scale, the development of resistant 
varieties would seem to be the most feasible means of control. 
SUMMARY 
(1) The spot of lima bean described in this paper has been observed 
in the home gardens in the southeastern part of Wisconsin for several 
years. So far as known, it has not been reported from other sections 
of the United States. 
(2) All varieties of lima beans so far tested are susceptible. No other 
species of legumes have been infected. 
(3) The disease is characterized on the leaves, where it is most con¬ 
spicuous, by more or less irregular spots with grayish center and defin¬ 
itely delimited purplish borders. In early stages the disease is charac¬ 
terized by purplish or brown spots, slightly depressed on the lower 
surface. In late stages the center becomes gray. The spots are never 
water-soaked and no exudate appears. 
(4) Petiole, stem, and pod lesions accompany the disease on the leaves. 
A small amount of exudation has been observed on the pods in the field. 
When kept in a moist chamber straw-colored exudate appeared on the 
pods in large droplets. 
(5) The disease was severe in its attack on lima beans in the vicinity 
of Madison, Wis., during the season of 1917. Such attacks occurred 
under conditions of heavy rainfall and moderately high temperature. 
During seasons with high temperature and light rainfall the disease was 
of little importance. While the disease may never be of great economic 
importance in home gardens, it has the potentialities, under favorable 
weather conditions, of causing considerable reduction in yield and would 
necessitate remedial measures where lima beans are grown commercially. 
(6) The causal organism is a medium rod motile by one to several* 
flagella which is described as Bacterium viridifaciens n. sp. It grows 
readily on a variety of culture media, producing white, glistening, opaque 
colonies. Beef extract agar, beef broth, Uschinsyk’s and Fermi’s solu¬ 
tion are turned green. It produces acid without gas in media contain¬ 
ing dextrose and saccharose, reduces nitrates, is non-acid fast and gram¬ 
negative. It is highly resistant to desiccation in diseased leaves but is 
killed within 24 hours on sterile cover glasses. There seems to be a 
gradual loss of pathogenicity when it is grown in artificial culture. 
(7) Foliage and stem infection is readily obtained by spraying water 
suspensions of young cultures on healthy uninjured plants. No pod 
inoculations have been made. 
