- SUSCEPTIBILITY OF VARIETIES OF APPLE TREES. 4] 
first grade in the markets, and if a purchaser buys trees guaranteed 
to be free from disease and of first grade, trees with distinct forms of 
disease should not be supplied. Orchardists should plant healthy 
trees and be willing to pay more for them if necessary. Since the 
initial cost of an orchard is only a small item in the entire outlay for 
its maintenance, it will certainly pay to plant the best grade of trees 
that can be bought. 
SUSCEPTIBILITY OF VARIETIES OF APPLE TREES TO THE DISEASE. 
DATA UPON A NUMBER OF COMMON VARIETIES USED IN EXPERIMENTS. 
The susceptibility of the different varieties of apple trees to crown- 
gall and hairy-root has not been discussed by others in any previous 
publication on the subject. Nurserymen have asserted for a number 
of years that certain varieties are extremely susceptible to the disease. 
Since the same varieties are not grown in all localities, sometimes one 
variety has been named as more susceptible and sometimes others. 
A request for a list of the varieties considered to be ordinarily most 
badly diseased with crown-gall and hairy-root was sent to fifty of the 
leading nurseries in various parts of the country to ascertain if there 
was any uniformity of opinion in this matter. . Each was requested 
to have the field superintendent send in the names of the six worst 
diseased varieties. In a compilation of thirty-two replies the follow- 
ing varieties were found to be the most badly diseased, those named 
oftenest being given first: Ben Davis, Early Harvest, Yellow Trans- 
parent, Wealthy, Grimes, Oldenburg, Wolf River, Red June, Gano, 
and Rome Beauty. All of these varieties except the last named have 
been included in the experiments of the Bureau of Plant Industry, 
from which data will be given later. 
Since obtaining these opinions reports have been received for three 
successive years from twelve nurseries, the number of diseased trees 
being given in the case of a large number of varieties. The reports 
are from nurseries in Utah, lowa, Nebraska, Kansas, North Carolina, 
Missouri, Illinois, Indiana, Ohio, and Virginia, and many of them were 
based upon careful counts made at the time of digging. These cor- 
roborate quite generally the opinions of the nursery superintendents 
as given in the preceding paragraph. They show, however, as would 
be expected, a variation year by year with the same varieties in the 
same locality. For instance, one nursery reports for the Gano the 
following percentage of disease during successive years: 1904, 15; 
1905, 46; 1906, 28. Another reports as follows for the Ben Davis: 
1904, 15; 1905, 40; 1906, 30. 
In order to obtain some idea as to whether in certain varieties there 
was a susceptibility to either crown-gall or hairy-root, or both, experi- 
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