THE PERSISTENCE OF VIABLE PYCNOSPORES OF THE 
CHESTNUT BLIGHT FUNGUS ON NORMAL 
BARK BELOW LESIONS 
R. A. Studhalter and F. D. Heald 
Introduction 
A study of the part taken by birds and insects in the dissemination 
of the chestnut blight fungus, Endothia parasitica (Murr.) And., has 
shown that both birds (6, 7) and insects (9, 10) can carry high numbers 
of pycnospores of this fungus. There are a number of possible 
sources from which these pycnospores may have been obtained, but 
it was thought that by far the greater number of them were brushed 
from both diseased and healthy chestnut bark during the normal 
movements of the birds and insects over these surfaces. This sup- 
position was based primarily upon the fact, previously reported (4, 5), 
that pycnospores of the chestnut blight fungus, generally called the 
summer spores, are produced in large numbers even during the winter 
months, when only an occasional spore-horn can be found, and that 
they are washed down the trunks of trees with every rain. 
It is natural to suppose that a large number of the pycnospores thus 
carried down the tree trunks would lodge on healthy bark below lesions. 
The work herein reported was undertaken in order to obtain some 
definite information on the numbers of pycnospores which find lodg- 
ment on normal bark, and the length of time they may remain viable 
after a rain. 
A preliminary test of seven pieces of normal chestnut bark was 
made by Mr. M. W. Gardner in February, 1913, in which he obtained 
from 130 to 4,700 viable pycnospores per square centimeter of bark 
surface on the day following a rain. 
Method 
Pieces of smooth chestnut bark about 4X4 cm. in area were cut 
out with a flamed scalpel at varying distances below blight lesions. 
Without touching the bark it was dropped into an envelope which 
had previously been folded crosswise, placed in another envelope and 
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