Jan, io, 1914 
Some Diseases of Pecans 
333 
Cultural Studies 
As grown upon corn-meal agar the optimum temperature for the fungus 
was found to lie around 20° C. (68° F.). No growth took place below 2 0 
or above 37 0 . The rate was slow at 4 0 , but gradually increased up to 
the optimum, and decreased somewhat more rapidly in rate above that 
point. At 35 0 a slight but abnormal growth occurred for a few days, 
but at the end of the 3-weeks' test, incubation at the optimum tem¬ 
perature failed to show any further signs of life in these cultures. 
Upon corn-meal agar the submerged growth varies but little from a 
sepia brown, while the aerial mycelium shows gradations from that to 
whitish. Usually a large number of dark-sepia to almost black pycnidia 
are formed upon this medium. The mycelium is straight and but little 
branched, with gradations from brown to almost hyaline. 
On corn-meal flasks the colonies appear very much as upon the corn- 
meal agar, though the aerial mycelium is usually much more luxuriant 
and cottony, becoming, however, somewhat felted with age. Pycnidia 
are developed in large numbers. 
On cooked-potato cylinders the colonies are brown ocher, varying also 
to a slightly darker shade. The surface is smooth and glistening, be¬ 
coming somewhat wrinkled with age. No aerial mycelium or pycnidia 
have been observed on this medium. The cells of the hyphae differ from 
those grown upon corn-meal agar in being more nearly isodiametric, with 
thicker and somewhat bulging walls. The mycelium possesses but few 
side branches, and the color varies from pale brown to almost hyaline. 
In cultures several weeks old the whole potato cylinder becomes some¬ 
what softened and turns brown, but no fungous mycelium is found except 
near the surface. The starchy contents of the potato cells become largely 
digested, though the walls of the deeper lying cells remain intact except 
for the breaking down of the middle lamellae. 
Upon synthetic agar the growth is brown ocher to sepia in the older 
and drier parts. The surface growth often becomes more or less wrinkled 
and moist-mealy in appearance in older cultures, while a pale brown 
to whitish aerial mycelium may or may not develop. Microscopically 
the hyphae very much resemble those developed upon the potato cylin¬ 
ders, but the thickening and bulging of the walls is often much more 
apparent. Indeed, the hyphae frequently break up into their constituent 
cells, and it is this behavior that gives the moist-mealy appearance to 
some cultures. 
Morphology and Taxonomy 
The study of this fungus in culture and upon the host has shown it to 
conform in characters with the genus Coniothyrium. However, no mem¬ 
ber of this genus has been found hitherto reported on the pecan or any 
nearly related host. It thus becomes necessary to give the fungus a 
new specific value until cultural and cross-inoculation work can establish 
