Jan. io, 1914 
Some Diseases of Pecans 
323 
where abraded and where the surface was left intact. The largest of these irregular 
spots covered as much as half the surface of the leaflets, and numerous perithecia were 
forming, though only a few were mature at this time. When 3 weeks old the spots 
had increased in area so as to involve most of the tissue, and most of the perithecia 
were mature, bearing the typical curved ascospores in abundance. No acervuli or 
scattered conidia were noted. 
Experiment No. 5 (May 29, 1912).—Twenty young seedling pecan leaves were 
placed in damp chambers and lightly sprayed with a distilled water suspension of 
conidia and ascospores from a 5-weeks-old cora-meal-agar culture (strain 17). On 
the third day small brownish areas had developed here and there over the leaf sur¬ 
faces. On the eighth day these had nearly covered the leaves, and numerous peri¬ 
thecia, together with an occasional acervulus, had developed in the dead tissue. 
(PL XXXVII, fig. B.) These fruiting bodies occurred in greater abundance on the 
lower side of the leaves, but frequently on both upper and lower surfaces. The incip¬ 
ient perithecia and acervuli developed beneath the epidermis, but later burst through 
and became partly superficial. 
Experiment No. 6 (Oct. 22, 1912).—Six vigorous but mature leafy pecan shoots 
were sprayed with a sterile distilled-water suspension of conidia from strain 123 
obtained from diseased nuts, and a similar number with strain 150 obtained from a 
naturally infected apple. The shoots were cut under water and the lower ends placed 
in bottles of water under slightly ventilated bell jars. Nine check shoots were treated 
in the same way, except that they were not inoculated. 
At three days many of the inoculated leaves in both sets had begun to show the dead, 
brownish areas characteristic of the disease. After seven days these areas had in some 
cases involved nearly the whole leaf, with the development of acervuli in moderate 
numbers. The check leaves were still green and healthy. 
Experiment No. 7 (Mar. 25, 1913).—Distilled-water suspensions of conidia from one 
apple strain and three pecan strains of the fungus were sprayed over young seedling 
pecan leaves in damp chambers. After three days sample leaves from each set were 
collected and prepared for microscopical examination. A small percentage of the 
conidia, varying somewhat with the different strains, had sent out germ tubes. Some 
of the short hyphse were terminated by appressoria. In one or two cases the germ 
tube was traced into the opening of a stoma. This method of infection agrees with that 
described by Shear 1 for Gloeosporiums on a wide variety of hosts. 
After five days several of the leaflets in each set exhibited typical infection areas 
up to 30 mm. in diameter. However, on account of a field trip, no further obser¬ 
vations were made on this experiment. 
NUTS 
Experiment No. i (Oct. 22, 1912).—These inoculations were from strain 123, 
obtained in October, 1912, from blackened nut shucks sent in from Thomasville, Ga., 
by Mr. C. A. Reed. Terminal shoots bearing healthy green pecans were kindly 
furnished by Mr. J. B. Johnson, of Manassas, Va. These shoots were cut under water 
to prevent clogging of the vascular system, placed with the cut ends in bottles of 
water, and sprayed with a distilled-water suspension of the conidia from this strain. 
All were then covered with bell jars ventilated at the base to prevent a too great 
stagnation of the air, but at the same time to furnish sufficient humidity to insure 
germination of the spores. The check shoots were treated in the same way, except 
that they were sprayed with distilled water alone. 
Group A consisted of 7 shoots bearing 9 nuts, the hulls of which were punctured 
with a sterile needle and sprayed with sterile distilled water. Group B consisted of 2 
1 Shear, C, L., and Wood, Anna K. Studies of fungous parasites belonging to the genus Glomerella. 
U. S. Dept. Agr., Bur. Plant Indus. Bui. 252, no p. t 18 pi., 4 fig., 1913. 
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