68 THE CROWN-GALL AND HAIRY-ROOT OF THE APPLE TREE. 
The planting of cull trees in the scion orchard can not be too 
strongly condemned, since the greater number of such trees are dis- 
eased with forms of crown-gall and hairy-root. Only healthy, vig- 
orous trees should be planted in the scion orchard. Any tree in 
such orchards that shows even a trace of disease should be removed. 
A scion orchard should be used only as long as it is healthy and vig- 
orous; then it should be replaced by a new orchard. 
SELECTION OF THE BEST KINDS OF SOIL FOR GROWING TREES. 
It is well known to experienced nurserymen that only certain tracts 
of land in any locality are suitable for growing trees. It has been 
strongly indicated by the results of the writer’s experiments that 
heavy, wet, clayey soils increase the amount of crown-gall present, 
and that trees on many well-drained soils show the least disease. 
In general the light, loamy, well-drained soils, where fertile, are the 
best for growing apple trees with a minimum of disease. 
CURE OF DISEASED TREES IN THE ORCHARD. 
Expervments by others.—When an apple tree has become diseased 
with crown-gall and hairy-root it is a question as to whether any 
curative method can be used to insure a healthy growth. Some 
writers, notably the following, have advocated cutting off the tumors: 
Howard (24), of Missouri, carried out the most extensive experi- 
ment in an attempt to cure crown-gall. He studied the subject for 
two years, employing many different remedies and combinations and 
experimenting with nearly 3,000 trees. He used the following: Cop- 
per sulphate (bluestone), iron sulphate (copperas), sodium chlorid 
(common salt), lime, sulphur, formalin, ammonia water, bichlorid of 
mercury (corrosive sublimate), copper carbonate, carbolic acid, hy- 
drocyanic acid, potassium dichromate, mercuric cyanid, silver 
nitrate, gas tar, kerosene oil, Bordeaux mixture, and hot water. 
The remedies were used in three ways: By dipping the roots in 
the materials; by sprinkling the soil with the solutions until the 
‘surface was wet just as trees were being planted; and by cutting 
away the galls and covering over the wounds with the materials to 
prevent their growing again. Howard’s results show that some of 
the compounds did prevent -the growth of the galls, but not without 
injury to the tree. He says that ‘“‘copperas, bluestone, and lime 
mixed together and applied to the wound was the best remedy of all 
for preventing a new growth of galls, although this was not entirely 
efficacious.” He mentions no control in which the galls were removed 
without treatment with fungicides. 
Butz (7), in Pennsylvania, took 60 apple trees and cut off the galls 
from 40, one-half of which he dipped in Bordeaux mixture before 
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