GALLS 
trees from the same lot may be planted 
without fear of bad results.” 
On the other hand, *Thompson, of Mis- 
sissippi, puts crown gall among the most 
serious apple diseases. 
Our observation leads us to the con- 
clusion that more crown gall occurs in 
our apple orchards, in connection with 
“Root grafting,’ than is generally sup- 
posed Often the graft fails to properly 
unite and a favorable opportunity for 
the entrance of the bacteria is presented. 
Great care should therefore be exercised 
in the grafting of nursery stock. 
7W. B. Alwood has given the results 
of experiments made with crown gall in 
grafting on diseased and healthy roots. 
Experiments showed: 
1. That there is practically no differ- 
ence in the susceptibility of varieties to 
infection. 
2. Experiments with grafting diseased 
scions on diseased roots cut into three 
sections. 
(1) The top cut, only five lived. Three 
showed cases of crown gall, and two were 
weak. 
(2) Of the middle cut, only six grew, 
and these were weak, and all showed 
cases of crown gall. 
(3) Of the third cut or tip of the 
roots, only one survived, and it had gall. 
3. Healthy scions on healthy roots. 
(1) From the first cut i1 strong 
healthy plants. 
(2) From the second cut eight strong 
healthy plants. 
(8) From the third cut five plants de- 
veloped, four healthy and one weak. 
There was not a case of crown gall in the 
lot. 
4. Wealthy scions with long roots, on- 
to diseased roots, set in the ground at 
considerable depth, to see if the disease 
would be communicated from the lower 
diseased root, to the healthy upper root. 
It was not so communicated. 
5. The diseased root of No. 4 was cut 
off the following year, and the healthy 
part planted. This developed no disease 
the second year. 
Bulletin 
+ Virginia Experiment Station, Bulletm 140 
147 Mississippi Experiment Station, 
1069 
6. Healthy graft on healthy root, but 
a piece of crown gall was bound to the 
root at the point of contact with the 
graft. Three out of 12 show crown gall, 
the other nine are healthy. 
7. A healthy scion on a healthy root, 
and a thin slice of diseased tissue was in- 
serted under the bark. Out of the 12 
planted, six grew and four showed more 
or less traces of gall. 
8. Twelve healthy scions were grafted 
onto healthy roots and inoculated with 
gall. Nine showed decided cases of crown 
gall, one suspicious and two healthy. 
9. Healthy scions were grafted onto 
healthy roots. After planting, some fresh 
galls were sliced with a sharp knife and 
used for inoculating the soil about the 
trees. Eleven plants grew, all healthy 
except that two of the plants show in- 
cipient cases of crown gall. 
10. Galls were cut away with a sharp 
knife. They have developed fibrous roots, 
but no normal roots. The part of the 
roots below the cut seems atrophied. 
Pocket Gophers and Crown Gall 
*Soft crown gall occurs frequently on 
roots injured by pocket gophers or mice. 
Of course the abundance of soft tissue in 
the root knots would probably lead a 
rodent to attack the diseased parts rath- 
er than a smooth healthy root. Yet, the 
fact that in some orchards, crown gall is 
rare except in trees whose roots have 
been injured by mice seems to indicate 
that the disease is more commonly the ef- 
fect rather than the cause of animal at- 
tack. 
N. Hollister, of the Biological Survey, 
writing from Banning, California, May 5, 
1909, stated that in that vicinity almond 
trees are killed by root knot, or crown 
gall, and he sent photographs of a four- 
year-old tree that had died from this 
disease. The old gopher tunnels had ex- 
tended to its roots and no doubt the roots 
had once been injured by these animals. 
From what is now known of the nature 
of this disease, and the fact that it oc- 
curs commonly on trees once injured but 
*David E Lantz, in the Year Book, De- 
partment of Agriculture, 1909 
