Mar. 3,1923 
Cray Mold of Castor Bean 
669 
Tabus I.— Sources of cultures of Sclerotinia ricini —Continued 
Cul¬ 
ture 
No. 
Date 
collected. 
Isolation method. 
Place collected. 
1919. 
41 
Mar. 16 
Not known. 
Santiago de las 
Vegas, Cuba. 
42 
...do. 
.do. 
.do. 
May 1 
Single ascospore.... 
Orlando, Fla. 
44 
May 29 
Tissue fragment.... 
.....do. 
45 
Dec. 15 
.do. 
Miami, Fla. 
1918. 
46 
Oct- 24 
.do. 
Plant City, Fla. 
Remarks. 
Received from S. C. 
Bruner, Pathologist. 
Do. 
From apothecia on field 
sclerotia. 
Reisolation from plant 
inoculated with asco- 
spore culture. 
From seed of lot 33. 
Isolated May 27 from 
light-weight seed from 
hulling machine. 
SI All these cultures were identical, showing conclusively the association 
of this one fungus with the castor-bean blight. Most of them, together 
with bits of the material from which they were isolated, were sent to 
Prof. Whetzel, at Cornell University, who verified their identity. 
APPEARANCE IN CULTURE 
Growth of the fungus on artificial media is very rapid. It is spreading 
and superficial at first, presenting a characteristically glistening appear¬ 
ance on the surface of the medium. Within 48 hours aerial hyphae 
begin to develop, in the form of erect single strands, the conidiophores. 
These develop very thickly and produce conidia often as early as the 
second day of growth. Soon the culture attains a light-gray color from 
the production of conidia, and as these become more abundant, it gradu¬ 
ally becomes darker till it is drab or even dark-olive gray.® Figures A 
and B of Plate 10 are photographs showing the appearance of the fungus 
on corn meal agar three days after inoculation. About the fourth day 
sclerotia begin to form at the edges of the culture in a tube. These are 
anywhere from mm. to 3 or 4 mm. in length, at first pale smoke gray 6 
then gradually darker in color till they are black. At first flat and 
closely appressed to the surface, they gradually become wrinkled and 
distorted. On a highly nutrient medium, such as oatmeal agar, they 
are very abundant; on a less nutrient medium, such as one made with 
a small quantity of com meal, less so. Appressoria, while present, are 
usually too small to be seen distinctly with the naked eye. Occasional 
cultures appeared in which they were massed together enough to pro¬ 
duce the characteristic appearance of appressoria in a culture tube. 
(PI. 11, A.) The writer’s paper containing the description of the fungus 
(ro) contains a drawing of a typical microappressorium. 
The general appearance of the fungus in culture is that of a typical 
Botrytis with the usual abundance of gray mold and black sclerotia. 
* Ridgway, Robert color standards and color nombnclaturb. 43 P.. 53 col. pi Washington, 
D. C. 1912. 
