682 
Journal of Agricultural Research 
Voi. xxm. No. 9 
be very dry. The absence of the disease in northern Louisiana, Arkansas, 
Tennessee, and northern Mississippi was further verified at this time by a 
personal survey. A field at Montgomery, Ala., was also found to be free 
from the disease. Neither had it occurred since the first visit, in plantings 
near Valdosta, Ga., Dothan, Ala., or Florence or McBee, S. C. 
By November 15 the mold had become exceedingly destructive in 
localities where it had been seen earlier. At De Land, Fla., where it had 
been causing perhaps 50 per cent loss in August, it was now affecting 
practically every inflorescence shortly after it came out of the sheath, 
making the loss a full 100 per cent. It had also appeared at points along 
the east coast, particularly near Miami, and it was even found at the 
plantation at Davie, on the border of the Everglades. Here also it was 
found to have spread to scattered plants of “ Palma Christi. ” 
Figure 1 is a map showing the location of castor bean plantings in the 
South where the disease did and did not occur as determined by personal 
field inspections by the writer and reports from others. The losses in 
those localities where the disease was present varied from 10 to 100 per 
cent. 
INFLUENCE OF WEATHER CONDITIONS ON THE PROGRESS OF THE 
DISEASE 
During the course of the various survey trips through castor-bean 
growing sections, the writer noted the definite effects of moisture and 
temperature on the development of the gray mold. Its presence and 
rapid spread in the various localities in Florida during July, August, and 
September were definitely traceable to the warm moist weather of those 
sections, where the wet season regularly occurs in the summer time. In 
certain localities in particular it was observed that there were showers 
every day, frequently even several times a day. Plate 2, A, shows 
typical cloud effects that result in the showery weather referred to. At 
night there almost invariably occurred a heavy dew. Figure 2 is a copy 
of a figure in a report of the Weather Bureau (79) showing the average 
monthly rainfall in different sections of Florida. This excessive moisture 
made an ideal condition for the development of such a fungus as this 
one, a gray mold. 
Figure 3, showing the daily rainfall ( 26) in particular localities for 
July, August, September, and October presents graphically the striking 
contrast in rainfall between typical localities where the disease was serious 
and those in which it did not occur. 
Particular attention is called to the correlation between the summer 
rainfall and the occurrence of castor-bean gray mold. At Bartow, Fla., 
protracted wet periods occurred throughout the summer, and the disease 
appeared early and was continuously destructive. At Miami, Fla., except 
for one period early in July, at which time the plants were not yet fully 
developed, the wet weather did not begin until September 9, after which 
there was hardly a day without rain until after the middle of October. 
There the disease did not begin to be destructive until late summer. 
Again, at Houston, Tex., continuous heavy rain did not begin till about 
October 7, and there too, the disease was not reported until late in the 
season. At Valdosta, Ga., and Florence, S. C., where the fungus did not 
develop at all, the rainfall that did occur was of short duration and always 
followed by long periods of dry weather. 
