Jan. 10, 1914 
Some Diseases of Pecans 
33i 
hemisphere beneath the dark-colored spot. The central part of this 
hemisphere is dry and pithy, slightly discolored, and surrounded by a 
definite dark-brown layer separating the diseased from the healthy parts. 
The tissues are slightly disorganized, but are not softened or entirely 
broken down. A bitter taste is imparted to the kernel. Microscopically, 
the fungus is found to enter the cells of the kernel, where the hyphae 
become partially broken up into their constituent cells. Outside the 
dark-colored boundary layer the tissues of the kernel are seen to be 
slightly discolored, although no signs of the fungus itself are seen here. 
It seems probable that enzyms or toxins (or both) excreted by the fungus 
may diffuse out into the healthy cells of the host and by partial digestion 
prepare the way for the entrance and progress of the parasite. 
MY COLOG IC AL AND PATHOLOGICAL STUDIES 
Isolation op the Fungus 
The affected pecan kernels received in the fall of 1911 from Thomas- 
ville, Ga., were washed for five minutes in a solution of bichlorid of mer¬ 
cury (1: 500), and in distilled water. Small pieces of the diseased internal 
tissue were then cut out under sterile conditions and transferred to 
Petri dishes of melted beef agar. Yellowish bacterial colonies resulted 
from two of the transfers, but a constant fungous type developed from 
all the others. The bacteria and the fungus were isolated and carried 
in pure culture for the following cultural and inoculation studies. 
Inoculations 
In all the inoculations the kernels were freed from the shells under 
semisterile conditions and placed upon sterile, moist filter paper in 
Petri dishes. Under these conditions the pycnospores or mycelium from 
a pure culture were placed upon the kernels either with or without 
slight abrasion of the surface. The checks were treated in a similar 
manner but without inoculation. 
Experiment No. i (Jan. 15, 1912).—The kernels from several stratified nuts were 
placed in Petri dishes and inoculated by slight abrasion (1) with spores of the fungus 
(strain 99), and (2) with the yellow bacteria (strain 101), while the kernels in the 
third dish (3) were merely abraded with a sterile scalpel. After eight days typical 
symptoms of the kernel-spot had developed in the first culture. (PI. XXXVII, 
fig. D.) The bacteria in the second culture had made a slight growth, causing an 
irregular softening of the superficial tissues, but without discoloration or other resem¬ 
blance to the kernel-spot. The check cultures were entirely sound. 
Experiment No. 2 (Jan. 25, 1912).—Kernels of well-cured Stuart pecans were inoc¬ 
ulated with the fungous spores, six kernels upon the uncut surface, and eight with 
a slight abrasion. Four kernels were held as checks. After 12 days typical spots 
had formed upon half of the first set and on all of the second set of kernels. Of the 
checks, two kernels were perfectly sound, the third exhibited a slight bacterial soften¬ 
ing at one end, and the last was softened throughout by a growth of Penicillium 
