EFFECT OF MOISTURE ON A SEED-BORNE BEAN 
DISEASE 1 
Lewis T. Leonard 
Physiologist , Soil Bacteriology Investigations, Bureau of Plant Industry , United 
States Department of Agriculture 
INTRODUCTION 
In a preliminary paper (9 ) 2 attention was called to a wilt disease of navy beans, 
Phaseolus vulgaris L., noted at Redfield, S. Dak., which seemed to arise from the 
application of legume bacteria culture to the seed prior to planting or to be favored 
by such application. Experimental work at Redfield in 1922 indicated that inocu¬ 
lation applied in the liquid form, or water applied in a similar manner to the pro¬ 
geny of the seed on whose plants the original observations were made, stimulated 
the disease to such an extent that it was possible to superficially differentiate the 
rows so treated from those untreated. It was concluded, therefore, that moisture 
was largely responsible for these differences: The initial stimulation afforded by 
this means to the disease organisms in and on the seed being sufficient to cause an 
appreciable effect which was in evidence practically the whole time during the 
vegetative period and was reflected in the harvest of beans. 
Moisture is artificially applied to many legume seed by inoculation with sus¬ 
pensions of nitrogen-fixing legume bacteria in water or nutrient solutions. Inocu¬ 
lation is not ordinarily a soaking process, although soaking has been recommended 
for certain legume seed; it is merely a case of light moistening generally followed 
by drying in air or immediate sowing. When carried out in the regular manner 
it will be very rare that stimulation of destructive bacteria or disease organisms 
will be perceptible. In the great majority of cases treatment with inoculation 
has been so decidedly beneficial that when a case to the contrary arises it is advis¬ 
able to trace it to its cause. 
REVIEW OF LITERATURE 
FUNDAMENTAL EFFECTS OF SEED SOAKING 
The effect of moisture on seed has been studied by many investigators and the 
literature concerning most of the studies is covered by Kidd and West. (8) The 
outstanding earlier work has been summed up by Wollny. (14) His general conclu¬ 
sion is that the harm occasioned by soaking in water was due to the loss of neces¬ 
sary soluble nutrients from the seed by osmotic transfer. This condition, it was 
found, is encouraged especially by excess water and is influenced by the species of 
seed, duration of the immersion, and the temperature of the water. Hiltner (7) 
found that long continued soaking in excess water reduced the disease-resisting 
power of the seed, encouraged the activities of destructive bacteria, but that 
moisture applied in such a manner as to simulate natural conditions had a bene¬ 
ficial effect. Kidd and West (8) using bean seed presumably free from disease which 
had been soaked for six hours in an excess of water at temperatures of from 5 to 
1 Received for publication Feb. 27,1924. 
* Reference is made by number (italic) to “Literature cited,” p. 496-497. 
Journal of Agricultural Research, Vol. XXVIII, No. & 
Washington, D. C. May 3, 1924 
Key No. G—390 
96035—24f-7 
(489) 
