Blister Canker 
35 
in old trees. In young trees the cells in this region are not 
so distorted and compressed as in mature trees. 
SEASONAL SUSCEPTIBILITY 
An attempt was made to determine at what season of the 
year trees are most susceptible to infection. Inoculations were 
made in two-year-old trees and in branches of mature trees, 
the branches ranging from one-half to one inch in diameter. 
The inoculations were made at about the same date in May, 
June, July, and August, respectively. All were examined at the 
same time the following winter. The data secured (table 9) 
are rather contradictory in that inoculations made in May in 
young trees made slightly less total growth than similar inocu- 
Table 9 — Comparison of rate of growth of mycelium from 
inoculations made at different seasons of the year 
DATE INOCULATED 
Two-Year 
-Old Trees 
OnG~lncii 
Mature 
W OOQ or 
Trees , 
Above 
Below 
Above 
Below 
Inches 
Inches 
Inches | 
Inches 
4.0 
12.5 
8.5 1 
19.0 
2.0 
8.5 
8.0 1 
20.5 
5.0 
11.5 
3.0 1 
7.0 
3.0 
7.5 
12.0 1 
13.5 
May 20-25 ^ 
3.0 
1.5 
7.5 
3.5 
7.0 1 
5.5 1 
11.0 
9.5 
2.5 
4.0 
11.0 1 
21.5 
2.5 
7.0 
16.0 1 
14.0 
2.0 
4.5 
10.5 1 
23.5 
2.5 
7.5 
5.0 1 
9.5 
18.0 1 
41.0 

Average 
2.80 
7.40 
9.50 1 
17.27 
12.0 
15.0 
1 
10.0 1 
15.0 
12.0 
12.5 
10.0 1 
20.0 
6.5 
8.5 
23.5 1 
28.0 
2.0 
6.5 
12.0 1 
18.0 
2.5 
5.5 
21.0 
19.0 
June 22-28 
1.5 
5.0 
12.0 
14.0 
2.5 
4.0 
7.0 1 
8.5 
2.0 
6.5 
13.0 1 
15.0 
2.0 
2.5 
10.0 1 
10.0 
2.5 
5.0 
10.0 1 
12.0 
1.5 
2.5 
8.0 1 
6.0 
6.0 I 
14.0 

Average 
4.27 
6.68 
1 
11.87 1 
14.96 
