CHESTNUT BLIGHT FUNGUS 1 65 
Table II 
Summary of Results Obtained from the Tests of Healthy Chestnut Bark below Lesions 
Place of Colleclion, 
Pa. 
Last Rain Before Test 
No. of Days 
Between Rain 
and Time of 
Collection 
No. of 
Tests 
Made 
No. of Viable Pycnospores per 
Sq. Cm, of Bark 
Date 
Am't., in. 
Max. 
Min. 
Average 
I 
Martic Forge 
I2/21/13 
0.13 
I 
7 
21,667 
833 
9,772 
2 
I/3-5/14 
2. II 
0 
7 
28,125 
0 
8,951 
3 
1/24/14 
1. 21 
2 
7 
6,500 
667 
2,734 
4 
West Chester 
1/24/14 
1-35 
2 
3 
1,975 
256 
955 
5 
5/12/14 
0.56 
14 
9 
1,181 
0 
165 
6 
6/4/14 
0.30 
I 
3 
172,222 
17,593 
75,000 
and January. Snow was on the ground during one collection, and 
not a single spore horn was found during these two months. That 
many pycnospores washed down by the winter rains (4, 5) remain 
clinging to healthy bark below lesions is definitely shown by the first 
four series in Table I, and the averages in Table II. 
It is to be expected, of course, that much higher results would be 
obtained during the summer, when pycnospores are formed in much 
larger numbers and spore-horns are plentiful. The single series 
tested in June, collected on the day following a rain of 0.30 of an inch 
yielded from 17,593 to 172,222 viable spores per square centimeter. 
The average for the June series was 75,000 per square centimeter 
(483,900 per square inch), while the average for the four series in 
December and January was 6,378 per square centimeter (41,151 per 
square inch). 
The distances below lesions at which the pieces of bark were taken 
varied from o to 70 cm., several pieces being cut at the very edge of 
the lesion. It is impossible to make any definite comparison between 
the number of viable spores obtained at the edge of a lesion and from 
points further down, for no two pieces of bark were cut below the same 
lesion at the same time, and no two lesions can readily be compared. 
From the data on hand, however, it would appear that the distance 
below the lesion has very little influence on the number of viable 
pycnospores present. Since pycnospores were very plentiful at the 
maximum distance tested, it seems certain that positive results could 
have been obtained at much greater distances. 
The majority of tests showed that spores of fungi other than 
Endothia parasitica were also present on the bark (Table I). It is 
interesting to note, however, that in the majority of the cultures a 
