APPLE DISEASES 
are known to occur among stone fruits as 
well as among apples. 
Small Fruits 
Raspberries, blackberries, loganberries 
(Figs. 1Cand3) are often affected with 
crown gall and probably other small fruits 
are also attacked. The disease not only 
causes galls on the i1oots, but on the 
blackberry, at least tumors often break 
forth in long lines from the interior of 
the canes. A case of what appeared to 
be hairy root on blackberry was sent to 
the Department of Plant Pathology dur- 
ing the summer of 1912. Considerable 
damage seems to result from the effects 
of the disease on these fruits and it 
is probable that soil infection and the 
spreading of the bacteria through the 
ground to healthy plants is much more 
serious than among orchard trees. Fruit 
trees should never be set immediately 
upon ground from which galled berry 
bushes have been grubbed out 
Grapes 
Most of the European varieties of 
grapes are quite susceptible to crown gall, 
while only a few of the American varieties 
are considered susceptible. On the grape 
the disease is found in two forms, as a 
root gall and as a cane gall. On cuttings 
and young plants the root form is most 
commonly found. These root galls are 
usually formed at a wound and conse- 
quently occur frequently at the graft 
union on grafted vines. On older plants 
the disease usually also attacks the stem 
extending from the crown upwards. On 
the canes the galls are usually confluent 
and occur in lines running lengthwise of 
the stem. The effect of the galls is to 
stunt the vines. The leaves are frequent- 
ly smaller and show poor color. The un- 
derground galls decay each year and 
other rot-producing organisms may gain 
entrance and aid in finally bringing about 
the death of the vine. The cane galls 
are reported commonly to start from in- 
fection in frost cracks. They may also 
start in wounds made by pruning or in 
any other way. The disease is spread in 
the vineyard in various ways, such as by 
463 
the water of irrigation, use of diseased 
cuttings and by insects 
No cure 1s known for plants that are 
already diseased and no definite recom- 
mendations can be made for the grower 
of Huropean grapes. It is suggested, how- 
ever, that where the disease is preva- 
lent, it would be worth while to try out 
experimentally some of the stocks recom- 
mended as resistant under more southern 
conditions in the United States with a 
view to using such as may prove hardy. 
In New Mexico, where crown gall has 
been very serious, the Rupestris St. 
George, Sweetwater, Seedless Sultana, 
Matosa and some others are found re- 
sistant and succeed on their own roots. 
Benefit has also resulted in the south 
from grafting the susceptible varieties 
on such resistant stock as the Rupestris 
St. George and Lenoir. Among the most 
susceptible varieties are the Mission, 
Muscat of Alexandria, Flame Tokay, Mal- 
aga and Rose of Peru. 
The following precautions should be 
taken whenever susceptible grapes are 
grown: Secure cuttings where possible 
from vineyards free from disease. Where 
frost is troublesome and infection occurs 
in the resulting frost cracks, plant deep or 
protect with some covering. It is best 
for the grower by propagating his own 
stock to avoid the possibility of introduc- 
ing crown gall through grafts or cuttings 
from infected districts. 
Hops 
Crown gall is reported as serious on the 
hop in some sections. Affected plants 
should be removed and burned. 
SUMMARY 
The Disease 
1. Crown gall in its various forms, 
which occur on a great variety of plants 
in many parts of the world, is caused by 
parasitic bacteria which enter the living 
cells of the host and stimulate them in 
some way to multiply excessively, thus 
producing tumors, the presence of which 
is usually detrimental to the welfare of 
the plant. 
2, The greatest losses resulting from 
erown gall occur in the nurseries where 
