46 Nebraska Agricultural Exp, Station, Research Bui. 12 
Later, trees were planted in jars of soil and watered from 
the top. Four grams of nitrogen, potassium, phosphorus, cal- 
cium and magnesium, respectively, were added in a 0.2 per 
cent solution weekly to a series of four jars each. The trees 
were inoculated as soon as they were in full leaf. They were 
examined ten weeks later but no appreciable difference could 
be found in the amount of infection. The trees which received 
nitrogen made a slightly faster growth, but there was no dif- 
ference in amount of growth made by the others. 
In the spring of 1915 two fourteen-year-old Ben Davis and 
two Jonathan trees of the same age were inoculated. A trench 
four feet deep was dug around each tree, close enough to re- 
move approximately one-third of the feeding roots. The inner 
wall was lined with tar paper to prevent a rapid growth of 
roots out into the soft wet soil with which the ditches were 
filled. 
The trees made very little growth but each bore a crop 
of undersized fruit. The leaves turned yellow and fell long 
before the surrounding trees shed their leaves. In 1916 both 
Jonathan trees bore a light crop but made little growth. One 
of the Ben Davis trees did not bear any fruit and the other 
only a few small apples. The leaves appeared yellow and 
wilted thruout the season. Several characteristic cankers 
were formed. 
When the inoculations were examined it was found that 
all of the heartwood and all of the sapwood except the two 
outer rings in the Ben Davis trees was infected, and in many 
instances all of the wood was infected, so that no data could 
,. be secured on the amount of fungous growth except to note the 
amount of wood still intact. The Jonathan trees were likewise 
found to be so badly infected that few reliable data could be 
secured. However, the fungus had made much slower lateral 
progress than in the Ben Davis trees as shown by sectioning 
the wood of the trunk and limbs. 
The comparative amount of infection is shown in plates 
XIV and XV. 
VARIETAL SUSCEPTIBILITY 
A great deal of variation is shown in the susceptibility of 
different varieties of apples to blister canker. There is also 
considerable variation within each variety. The data given 
in table 12 while not conclusive give a fairly reliable indica- 
tion of the comparative susceptibility of the different varieties. 
These data do not agree in all cases with field observations. 
