706 
Journal of Agricultural Research 
Vol. XXIII, No. 9 
chamber was removed the disease stopped progressing, as it did with 
the castor bean plants. Besides the geranium, eggplant (Solanum 
melongena Linn.) seedlings became very slightly infected. Among the 
plants that were entirely unaffected by the organism were tomato, 
onion, snapdragon, sunflower, string bean, tobacco, and lettuce. 
In Florida, during the season most favorable for infection, a few other 
plants belonging to the Euphorbiacese, the family to which the castor 
bean belongs, were inoculated under the same conditions as those given 
castor beans. Plants inoculated were five or six each of Jatropha 
(Jatr op ha sp.), Cassava (Manihot ultilissima Pohl.), and Poinsettia 
(Euphorbia pulcherrima Willd.). Slight but definite and characteristic 
lesions were produced on all of these, but in no case did the organism 
spread sufficiently to indicate that it might ever become active as a para¬ 
site on any of them. At the same time geranium plants were inocu¬ 
lated, and with similar results. All the lesions dried up after moist 
chambers were removed, even though castor beans in the field were 
meanwhile actively attacked. 
Throughout the summers of 1918 and 1919, during the course of sur¬ 
vey trips through the various infected localities, a close watch was kept 
on all manner of vegetation in the vicinity of diseased castor bean fields 
for possible natural infection. Other than castor beans no diseased 
plants were found for which the castor bean gray mold was responsible. 
The writer considers it safe to state that in his opinion the gray mold 
organism, fatal as it is to the castor bean crop, need not be considered a 
menace to any other crop. It appears to be very narrow in its host 
limitations. 
VARIETAL SUSCEPTIBILITY 
In order to make a test for possible varietal resistance, a collection of 
as many different varieties of castor beans as possible was made during 
the winter of 1918-19. These consisted principally of varieties grown 
by the Office of Drug and Poisonous Plant Investigations of the Bureau 
of Plant Industry, at Florence, S. C. Twenty varieties were obtained. 
These were supplemented by typical “Palma Christi” and a few selec¬ 
tions of what appeared to be distinct varieties from the miscellaneous 
assortment included in the Bombay seed. They were planted in a field 
surrounded by an abundance of infective material. Results were not as 
satisfactory as might have been wished, owing to a number of adverse 
circumstances, but general conclusions can be drawn. Plants of the 
more ornamental type, with stalk, foliage, and sometimes pods in dif¬ 
ferent shades of red or reddish green, were the most resistant, the pods 
especially being coarser and obviously tougher. All the smaller, many- 
branched plants, which by their yield indicated commercial possibilities, 
showed high susceptibility to the disease. Many of them at the close of 
the season had as high as 90 per cent of the inflorescences affected, and 
practically all over 50 per cent. Cross pollination in a castor-bcan field 
probably occurs very extensively. It would require years of work to 
develop pure strains and then to select and breed for desirable qualities 
combined with resistance before permanent results in the way of control 
could be secured. 
CASTOR BEAN HULLS FOR FERTILIZER 
Castor bean hulls have a high potash content, consequently there was 
considerable agitation during the winter following the harvesting of the 
