THE NATIONAL NURSERYMAN 
23 
FIELD STUDIES OF THE CROWN-GALL AND HAIRY- 
ROOT OF THE APPLE TREE 
Important Bulletin. Investigations Still in Progress 
Editorial notice was made of Bulletin 186, by George G. 
Hedgcock, pathologist in fruit disease investigations of the 
Department of Agriculture, in our last number. Addi¬ 
tional reference is herewith presented on the ground of the 
extreme importance to nurserymen of this investigation. 
Mr. Hedgcock shows by “actual experiment that in the case 
of the milder and usual forms of the disease, little or no 
injury is appreciable in young orchards; that more intense 
forms may be injurious; but in orchard these rarely develop 
from the milder forms.’’ He also indicates how the disease 
may be lessened if not eliminated by propagating methods. 
The following recommendations are offered by the 
author as the gist of his findings in this investigation, which 
has covered a period of five or six years: 
“The crown-gall and hairy-root of apple trees is pri¬ 
marily a nursery disease, gaining entrance most frequently 
the first year. In a well regulated nursery it is desirable to 
grow and sell the best trees that can be obtained and at the 
same time not increase the cost of production. With this 
in view the following recommendations are made: 
(1) In order to keep, the nursery as free as possible 
from the disease all diseased trees should be left in the field 
at the time of digging and burned as soon as dry. 
(2) The nurseryman should, as far as possible, ge^ 
scions from healthy trees by growing them under careful 
selection or purchasing them from others who do this. 
Never plant diseased trees in the scion orchard. 
(3) Buy the best grades of healthy seedlings for budding 
and root grafting. Insist that growers of apple seedlings 
cull out and bum all diseased ones at the time of digging. 
(4) Make close-fitting root grafts, avoiding blunt ends 
of the root and scion in the union. Wrap with unwaxed 
cloth or continuous-thread wrapping, covering completely 
and firmly the wounded edges in the union. The root and 
scion should be approximately of the same diameter. 
(5) Store root grafts preferably in sand. If the period 
of planting is delayed beyond two weeks they should be 
placed in cold storage at a temperature a few degrees above 
the freezing point. 
(6) Plant the union of root grafts about three to four 
inches below the surface of the ground. Be careful not to 
break the callus in planting and avoid wounding the young 
plants in cultivation. 
(7) Propagate by budding, as far as possible, the few 
varieties most susceptible to crown-gall and hairy-root. 
Among these are the 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 cer¬ 
tain, as shown by the results of experiments, and an in¬ 
creased 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 in its 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 rasp¬ 
berries, 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 disease 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 
diseased 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. In some localities and under certain soil condi¬ 
tions healthy trees with much-branched, fibrous roots are 
grown. These roots are to be distinguished from hairy-root 
formation, which is characterized at the beginning 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 precaution should be dipped in a weak 
solution of some antiseptic, as one-tenth of one per cent of 
corrosive sublimate, for five minutes and washed in water 
before planting.’’ 
ALABAMA STATE HORTICULTURAL SOCIETY. 
The eighth annual meeting of this progressive society will be 
held in Birmingham, Alabama, Thursday and Friday, Jan. 19 and 
20. An excellent program has been prepared, and a profitable 
meeting is expected. Secretary, P. P. Williams, Auburn, Ala. 
