Blister Canker 
68 
A number of inoculations were made with ascospores on 
pruning wounds 1 to 2 inches in diameter. These wounds had 
been covered six months before the inoculations were made. 
Similar wounds were made and thoroly disinfected three 
weeks before being inoculated. The results are given in table 
16. It was not noticed until too late to remedy the omission 
that no check was left for the series of disinfectants. 
Table 16 — Efficiency of various coverings and disinfectants 
used for pruning wounds in preventing infection^ 
TREATMENT OF WOUNDS 
X OlcLl XNUIIl- 
ber of In- 
oculations 
WiimDGr or 
Effective 
Inoculations 
Per Cent 
Effective 
COVER 
Asphaltum (in gasoline) 
39 
7 
17.95 
V^hite lead 
35 
5 
14.29 
Venetian red 
31 
13 
41.94 
Pine tar 
16 
5 
31.36 
Coal tar 
11 
4 
36.36 
White lead and copper sul- 
phate 
35 
4 
11.43 
No cover 
51 
49 
96.08 
DISINFECTANT 
Phenol 
15 
11 
73.06 
Mercuric chloride 1-500 
16 
4 
25.00 
Copper sulphate saturated 
solution 
15 
3 
20.00 
Formalin 2 0% 
12 
8 
66.67 
Lime sulphur 32° Baume 
14 
6 
42.86 
Iron sulphate saturated so- 
lution 
11 
5 
45.45 
*Covers were applied six months before inoculation, disinfectants three 
weeks before inoculation. 
The evidence indicates that suitable dressings and disin- 
fectants aid very materially in preventing infection. Liquid 
asphaltum, and white lead and oil appear to be of about equal 
value. Where either was used there was very little cambium 
injury and no checking of the wood beneath. In a fev/ cases 
the covering raised in blisters which later broke and per- 
mitted infection. This difficulty was overcome by making a 
thin application of the paint and later puttmg on a heavier 
coat. Both pine tar and coal tar were readily absorbed and 
much checking of the wood occurred. There was also consid- 
erable cambium injury. 
