| Material Information
||Gray mold of castor beans
||Press bulletin University of Florida. Agricultural Experiment Station
||2 p. : ;
||Stevens, H. E ( Harold Edwin ), b. 1880
||University of Florida, Agricultural Experiment Station
||Place of Publication:
||Castor oil plant -- Diseases and pests -- Florida ( lcsh )
Botrytis -- Control -- Florida ( lcsh )
Fungal diseases of plants -- Florida ( lcsh )
||government publication (state, provincial, terriorial, dependent) ( marcgt )
non-fiction ( marcgt )
||Statement of Responsibility:
||"August 14, 1918."
| Record Information
||University of Florida
||University of Florida
||All rights reserved by the source institution and holding location.
||ltqf - AAA6512
ltuf - AEP5882
oclc - 52786395
alephbibnum - 000934815
PRESS BULLETIN No. 296
UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATION
GRAY MOLD OF CASTOR BEANS.
H. E. STEVENS
A fungus disease that has appeared on the castor bean within
the last two weeks is causing serious injury to the crop in many
regions of the State. It is a gray mold that attacks the fruit
spikes in various stages of development. The unopened flower
buds, flowers, and nearly mature pods are attacked by the fungus.
In some cases from 50 to 90 percent of the plants in a field are
affected with the disease. Rain and shady conditions seem to
favor a rapid spread of this mold.
The disease is at once recognized by the grayish, webby mass
of fungus growth on the affected heads. In well developed cases
from one-half to three-fourths of the affected head will be envel-
oped by a gray, webby mass more or less powdery in appearance.
Pods and flowers in a head that are killed by the fungus become
brown and covered with a dusty gray, powdery mass which con-
tains countless numbers of spores. The disease appears to start
at one point and spreads rapidly until the entire head is affected.
The fungus also attacks the stem of the fruit spike and flower
stems, causing at first a dark, watery rot. The affected part soon
dies, turns brown and becomes dry.
The first appearance of the disease is marked by a dark-colored
spot or stain usually on one or more adjacent pods. This spotting
sometimes appears first on the stem of the fruit spike or on the
pod stems. The affected tissue is found to be rotted and watery.
No fungus growth is visible at this stage, and the remainder of
the pods or heads appears green and normal. Three or four
days later a fourth or a half of the head may be enveloped with a
grayish growth, and all parts covered by the fungus are killed.
The disease is caused by a fungus which appears to be a new
species of Botrytis. Specimens were sent to Mrs. F. W. Patter-
August 14, 1918
son, Bureau of Plant Industry, U. S. D. A., who reports the fun-
gus as an undescribed species of Botrytis. Very little is known
of its habits at present and it does not seem to have been reported
on the castor bean before. Under moist conditions the fungus
produces spores (seed) in countless numbers in the webby growth
enveloping the affected heads. These are readily scattered by
the wind and insects and infect other fruit heads.
The fungus is very active under moist shady conditions and
during periods of rain and cloudy weather it may become very
destructive, especially where beans are closely planted and are
making vigorous growth.
The rapidity with which this fungus has developed and spread
within the last two weeks, and the nature of the castor bean plant,
offer little encouragement for an easy method of control. Where
it is widely scattered thru a field very little can be done to protect
the fruit heads that may develop during the rainy season. After
the dry season comes on the disease will probably cause small
In fields where the disease is just appearing and only a small
number of heads are affected, further loss may be prevented if
immediate steps are taken to suppress it. All affected fruit heads
should be cut off and put directly into a pail of kerosene and car-
ried from the field and burned. Plants from which affected heads
are cut should be thoroly sprayed with bordeaux mixture, 4-4-50
formula, to kill spores that have lodged on the leaves and stems.
The flower and fruit heads on all plants in the vicinity of dis-
eased ones should be thoroly sprayed with bordeaux. An area of
50 to 100 feet beyond all diseased areas should be sprayed and
inspected frequently for new outbreaks.
State Papers Please Copy.