Blister Canker 
47 
Field observations indicate that varieties such as Missouri, 
Janet, and Maiden Blush are comparatively less susceptible 
than conclusions drawn from table 12 would indicate. In the 
main, however, field observations and inoculation data corre- 
spond quite closely. The inoculations in this series were all 
made in the heartwood during the same week and were exam- 
ined at the same time. 
It was noted in examining young trees which had been 
inoculated that when the varieties were on their own roots 
the susceptibility of the roots corresponded to that of the tops, 
but in budded trees where all of the roots had come from the 
seedling stock the roots showed all degrees of susceptibility 
ranging from great resistance to great susceptibility. 
There was less difference in the percentage of inoculations 
which proved effective in the different varieties than in the 
comparative amount of growth made by the effective inocula- 
tions. The difference was most noticeable where inoculations 
were made in active xylem. The percentage of effective inocu- 
lations was high in all varieties where the inoculations were 
made in the heartwood. On account of having a very limited 
number of trees of many of the different varieties it was im- 
possible to m^ake enough inoculations to furnish satisfactory 
data on this phase of the subject. 
According to the data given above and field observations 
the varieties are tentatively grouped as follows : 
Very 
Moderately 
Moderately 
Very 
Resistant 
Resistant 
Susceptible 
Susceptible 
Oldenburg 
Jonathan 
York 
Delicious 
Wealthy 
Winesap 
Willow Twig 
Ben Davis 
Arkansas 
Rome Beauty 
Gano 
Arkansas Black 
Maiden Bluch 
Yellow 
Janet 
Champion 
Transparent 
Minkler 
Grimes 
Fameuse (Snow) 
Missouri 
Stayman Winesap 
Northern Spy 
Virginia Beauty 
Chicago 
Wolf River 
Yates 
Northwest 
King David 
Greening 
Walbridge 
Malinda 
Susceptibility may and no doubt does vary in different 
localities and under different conditions as does susceptibility 
to apple scab and apple blotch (Cooper^) . Variation in suscep- 
