464 
the soil becomes contaminated and the 
trees in their young and tender condition 
are particularly susceptible to infection 
through wounds and at the union of stock 
and scion in root-grafts. 
3. In the orchard the effects of the di- 
sease are sometimes severe and some- 
times slight, depending on many condi- 
tions. Apples do not suffer so much 
damage as do peaches, berries and other 
fruits. An attack of crown gall is usually 
detrimental, often serious, and some- 
times fatal. A good many affected trees, 
however, recover or become resistant to 
the disease. There seems to be little 
spreading of crown gall in most orchards. 
The Control 
4, In order to keep crown gall under 
control in the nursery, trees or small 
fruits should never be grown’in land 
previously infected with the disease. Such 
plants as become infected should not be 
allowed to remain in the soil until the 
galls decay, but should be removed and 
burned. Neither root nor scion used in 
root-grafting should come from stock hav- 
ing galls or hairy root, and the graft- 
ing and wrapping should be carefully 
done. 
5. All nursery stock should be careful- 
ly inspected and all trees showing evi- 
dence of crown gall and hairy root or 
previous cutting-off of galls should be dis- 
carded. Fruit inspectors should use care 
in inspecting stock and make sure that 
every tree condemned is really affected 
with crown gall or hairy root. All warty 
appearances are not necessarily crown 
gall nor are all fibrous roots necessarily 
hairy roots. A whole shipment should 
never be condemned because a few trees 
are infected, since investigation has 
shown that there is little or no danger 
of infection spreading from diseased trees 
to healthy stock in the same shipment. 
6. Growers should never plant a 
diseased tree. It is better to discard an 
affected tree than to run the risk that 
it will never pay interest on the spot of 
ground it occupies. 
7. Trees which are found affected with 
crown gall in the orchard should be al- 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
lowed to remain if still profitable, but if 
unprofitable should be removed. Recoy- 
ery sometimes results from the complete 
removal of galls with sterilization of the 
wounds. Cutting out is recommended, 
especially in fire blight districts, since 
galls afford favorable points for blight in- 
fection. 
8. On account of the great difference 
in susceptibility of different varieties, a 
good opportunity is presented in the di- 
rection of the selection and breeding of 
resistant or immune varieties among 
fruits like the raspberry and grape, and 
possibly also among some of the tree 
fruits. 
Bibliography 
1905. U. 8S. Department Agriculture, Bu- 
reau Plant Industry, Bulletin 90, part 
2. 
1910. U.S. Department Agriculture, Bu- 
reau of Plant Industry, Bulletin 183. 
1911. U. 8S. Department Agriculture, Bu- 
reau of Plant Industry, Bulletin 213. 
1912. U. S. Department Agriculture, Bu- 
reau of Plant Industry, Bulletin 255. 
1912. California Experiment Station, Bul- 
letin 235. 
1918. New Mexico Experiment Station, 
Bulletin 85. 
Crown Gall and Legume Inoculation 
The crown gall organism has been 
found in tumors somewhat resembling 
the normal nitrogen-fixing nodules upon 
the roots of alfalfa, crimson clover, and 
alsike clover. For this reason great care 
should be taken in using soil or cultures 
for inoculating legumes in regions which 
may sometime be used for sugar beets or 
for orchards. 
It is usually possible to distinguish be- 
tween the two forms of nodules by their 
external appearance. The nitrogen-fixing 
nodules appear to be an outgrowth of the 
root itself and has no more affect upon 
the root than any natural outgrowth. The 
interior of the nodule contains flesh color- 
ed cells full of bacteria. On the other 
hand the crown gall tumor causes much 
distortion of the root, frequently forcing 
it to branch in many small rootlets which 
