74 THE CROWN-GALL AND HAIRY-ROOT OF THE APPLE TREE, 
Wealthy, the Yellow Transparent, the Wolf River, the Ben Davis, and 
the Northern Spy. 
(8) Avoid heavy, wet soils, since they favor an increase of disease. 
(9) Growers of seedlings should avoid wounding the young trees 
with the hoe or other implements of cultivation. 
That these precautions will decrease the disease is certain, as shown 
by the results of experiments, and an increased profit will result from 
their use. For example, wrapping with a close, tight, cloth covering 
decreased the percentage of diseased trees 12.9 per cent and resulted 
in an increase of stand amounting to 23.9 per cent of the original root 
grafts planted. This, based on 15,000 grafts to the acre, is a saving 
of $214.80 per acre. The continuous wrapping of root grafts with 
thread is more easily and cheaply done and promises to give equally 
as good results. 
The orchardist is advised to plant the healthiest trees obtainable, 
since the initial cost of the orchard is only a small part of the final 
outlay. If a tree becomes diseased during the first three or four 
years so that its growth is hindered, dig it up and plant a healthy tree 
inits place. If trees in an older orchard are diseased, but still bearing 
profitable crops, allow them to remain in the orchard, unless there is 
danger of infecting more profitable plats of raspberries, grapes, or 
peaches. In such case they should be removed, since crown-gall 
from the apple tree may infect these plants. 
If the growing of nursery stock were confined to apple trees, nursery 
inspection for crown-gall would hardly be necessary. Since the dis- 
ease attacks and kills grapevines, raspberries, and probably peach 
trees, and since it may be communicated to them from apple trees, it 
is clearly the duty of a nursery inspector to insist that apple trees dis- 
-eased with crown-gall shall not be sold. It is best to include in the 
same category apple trees diseased with hairy-root. 
On the other hand, an inspector should be certain that apple trees 
are diseased with crown-gall or hairy-root before condemning them. 
Warts and pimples are not necessarily crown-gall, nor are fibrous 
roots certainly hairy-root. The tendency to form fibrous roots 
exists under certain soil conditions (PI. ITI, fig. 4). In some local- 
ities and under certain soil conditions healthy trees with much- 
branched, fibrous roots are grown. These roots are to be distin- 
guished from hairy-root formation, which is characterized at the begin- 
ning by clustered, fleshy, often fasciated roots, which later become 
fibrous through shrinking. Only plainly diseased trees should be 
rejected; other trees in the bundle should not be condemned on 
account of the presence of a diseased tree, but as a matter of precau- 
tion should be dipped in a weak solution of some antiseptic, as one- 
tenth of 1 per cent of corrosive sublimate, for five minutes and washed 
in water before planting. 
186 
