May 3,1924 
Effect of Moisture on Seed-Borne Bean Disease 
493 
PRESENCE OF WILT SYMPTOMS 
Observations were made on the experiments by counting all of the plants in 
a row and also the plants which gave evidence of wilt disease symptoms or were 
dead either on account of drought, injury, or other disease. 
The effect of drought on the mortality among the beans at Woodward, Okla., 
is shown in Figure 1. If we consider this a constant factor the results may still 
have a meaning as regards the effect of the combination of moisture and disease. 
Table II.— Soil types , initial moisture and dates of planting beans at the various 
places of experiment 
Place of experiment 
Type of soil 
Initial 
moisture ° 
Date of 
planting 
Date of 
observation 
Arlington, Va__ 
Clay loam.. 
Per cent 
11 
10.7 
7.9 
6 .4 
2.8 
7.9 
4.9 
June 15,1923 
May 18,1923 
May 3,1923 
June 26,1923 
May 23,1923 
May 26,1923 
May 12,1923 
Sept. 10,1923 
Aug. 4,1923 
Aug. 10,1923 
Aug. 21,1923 
Aug. 24,1923 
Aug. 1,1923 
Akron, Colo... 
Chico, Calif_ 
Light sandy loam. _.. 
Sandy loam__ 
Leeland, Md.... 
Chester loam... 
Mandan, N. Dak... 
Redfield, S. Dak__ 
Woodward, Okla.1_ 
Black sandy loam. 
Black clay loam... 
Canadian sandy loam... 
a Determinations made by Franklin W. Marsh of the Office of Soil Bacteriology, United States Depart¬ 
ment of Agriculture 
At Redfield and Woodward, there is a consistent increase in the amount of 
disease corresponding to increasing applications of moisture. Excluding the 
data from Mandan there is a general indication of the same result at all other 
places but it is less striking than at Woodward and Redfield. Nodules were 
present on roots at all places. 
Among the other legumes used only the Robust beans showed occasional symp¬ 
toms of the wilt. 
SEED HARVEST 
The seed were harvested at all places except Woodward and Akron. They 
were examined for the presence of diseased and abnormal seed. The figures in 
Table III give in detail the yields from the various places together with the 
results of the pickage. 
The average of the effect of the moisture treatments are compared with the 
control and dry treatments in Figure 2. These are shown together. It is sig¬ 
nificant that in each case the crops from the seed planted dry exceed those of 
the moisture treatments. 
DISCUSSION 
EFFECT OF RAINFALL AND TEMPERATURE 
To determine whether a correlation existed between the extent of the disease 
and the rainfall a study has been made of the records from Redfield and other 
places at which the experiments were made. (fig. 3). 
To give an idea of the condition of the soil at Redfield as regards moisture, 
rainfall prior to planting has been considered. The period covered following 
the planting is the approximate time of vegetative growth for navy beans. 
If we consider the first three years only, it will be noticed that in 1920, when 
the damage was the greatest, the rainfall was also excessive, but if the record of 
1923, also a rainy year, is included this deduction is vitiated by the fact that 
the damage in this year can not be considered excessive. 
A review of the rainfall data in 1923 at the various places where the experi¬ 
ments were made does not indicate great differences in total or periodical rainfall 
between the dry-land and humid sections. At Chico, Calif., the rainfall was 
slight, but it was supplemented by irrigation at six different times during the 
season. There seems to be no correlation between the moisture in the soil 
at planting time and the subsequent amount of disease. 
