Mar. 3 ,1923 
Gray Mold of Castor Bean 
707 
1918 crop for their use as fertilizer. The one objection to this procedure, 
in case castor beans had become a staple crop, would have been the wide¬ 
spread distribution of the gray mold that might have followed. This 
danger might have been overcome by grinding the hulls and mixing them 
with acid phosphate and other ferilizers at the fertilizer plants. The 
close contact of the hulls to the strong acid of the fertilizer would possibly 
have quickly killed the fungus. No investigations to check this up were 
undertaken, however. 
CONTROL EXPERIMENTS 
Various plantings of castor beans were made in the spring of 1919 on 
different areas of vacant ground at Orlando, Fla. The sites were chosen 
particularly with reference to proximity to infected fields of the previous 
season's growth. Lot A consisted of an area of about V2 acre cut out in 
the middle of a large field which had been badly diseased in 1918. The 
soil was a fertile “ hammock-land ” type, bordering one of the numerous 
small lakes in the vicinity of Orlando. It required no fertilization but 
was prepared by first pulling up and clearing away the remains of last 
year's plants, then simply plowing and harrowing. This was done the 
last week in February. The field was divided into 1/10-acre sections for 
convenience, and plantings were made of various lots of seed during the 
first week in March. A frost the night of April 2 killed many of the 
plants which were well up, so a day or two later replantings were made, 
these being final. Lot B consisted of a portion of a lot 50 by 150 feet, 
approximately mile from Lot A, which was the nearest of last year's 
plantings. Lot C consisted of another piece of ground at a distance of 
approximately mile from the first field, covering an area 200 by 150 feet 
in dimensions. This was upon sandy soil and required considerable 
fertilizer. Plate 2, A, is a general view of this field upon which the greater 
part of the control experimental work was conducted. 
During the summer of 1918, when the disease appeared at its height, 
the standard fungicide, Bordeaux mixture, was recommended provi¬ 
sionally as a possible means of control (16, 17). This spray has been 
recommended more or less extensively for that type of trouble, as for 
instance by Stevens and Hall (15) for Botrytis diseases (Botryose) in 
general. As a rule, however, the only practicable means for controlling 
Botrytis diseases of crops appears to be the application of sanitary 
measures, namely, the destruction of diseased parts and of diseased 
plant debris and thinning or otherwise improving ventilation and doing 
away with excessively moist conditions. It seemed advisable to give 
fungicide application a thorough trial for this disease, however, and this 
was done in lot C during the summer of 1919. 
A few preliminary experiments pointed out as a method of procedure 
the following: The portion of the field to be tested was divided into four 
sections, each containing nine 150-foot rows. These four sections were 
to be treated, respectively, with (1) Bordeaux dust, (2) lime and sulphur 
dust (containing 10 parts sulphur to 90 parts lime), (3) Bordeaux spray, 
4-4-50, and (4) lime-sulphur spray, 1-30. The latter was found to be 
definitely injurious in that strength, so after the first application 1-40 
was applied. The first three rows in each section were treated twice a 
week, on Wednesday and Saturday; the second three once a week, on 
Saturday; and the third three left untreated as controls. Before start¬ 
ing the experiment the plants were examined thoroughly and all diseased 
and ripe spikes cut off and dropped to the ground, 
