GALLS 
damage as it is the decay of the hyper- 
trophied tissue due to irritation caused 
by the work of the worms. They make 
conditions favorable for the attack of 
wood rot fungi which hasten the decay. 
*Schofield gives the following list of 
plants commonly attacked: Beets, car- 
rots, celery, egg plant, lettuce, carnation, 
muskmelon, pumpkins, potatoes, salsify, 
squash, tomato, watermelon, clover, cow 
peas, rape, soy beans, catalpa, cherry, elm, 
peach. The following are subject to at- 
tacks of nematodes and although these 
plants are not in themselves liable to 
serious injury, they should not be plant- 
ed on soil infested with it for fear of 
keeping the gall worm alive: Alfalfa, 
vetch, sweet clover, asparagus, cabbage, 
cauliflower, garden peas, horseradish, 
strawberries, kale, lima beans, onions, 
radishes, spinach, sweet potatoes. 
The following plants are seldom, if 
ever, affected with them: Barley, oats, 
wheat, rye, corn, sorghum, milo, kaffir, 
timothy and redtop. At present no 
method is known to eradicate the pest 
from infested soils. 
For MrtHops oF CoNrTRot, 
Potato Pests. 
Crown Gall of Alfalfa 
7Galls and gall-like swellings appear 
on the main roots just at the surface of 
the ground and the plants die. The 
trouble is favored by excessive moisture 
in the soil and is caused by a fungus, 
Urophlyctis alfalfae. This new disease in 
California had not been reported any- 
where else in this country at this writ- 
ing (June, 1911). 
Gall of Commerce 
There is a form of gall called the 
“Gall of Commerce” which is a product 
of the gall fly (Cynips), which lays its 
eges in the soft twigs of an oak in West- 
ern Asia and Eastern Europe. They are 
rich in tannin and are used in making 
ink, dyeing, tanning, etc. 
Fungus Galls on Trees 
Professor J. W. Toumey, formerly of 
the Arizona station, has shown that a 
see under 
* Nevada Experiment Station Bulletin 91. 
' tk Smith, California Experiment Station Bul- 
etin . 
1071 
warty growth is due to a microscopic 
vegetable organism-——-a slime mould fun- 
gus, which in the case of the parasite 
determined for Arizona soils has been 
named for that investigator, Dendro- 
phagus globosus. There is evidence to 
show that when the trees are transplanted 
to the orchards, the galls continue to 
grow, forming ultimately large warts. 
When they girdle the trunk they interfere 
with the movement of the sap. Young 
trees often die of the disease. The galls 
of varying sizes affect the base of the 
trunk, the larger roots, and sometimes oc- 
cur on the stem above the surface of the 
soil. Affected trees show signs of starva- 
tion, yellowish foliage and enfeebled 
growth. 
*Inseet Galls 
What are commonly known as galls are 
vegetable excrescences and comprise all 
abnormal vegetable productions develop- 
ed on plants by action of animals, more 
particularly by insects, whatever may be 
their form, bulk or situation. 
For the larvae of these insects, the galls 
provide shelter and sustenance. The ex- 
citing cause of the undue or excessive 
growth in the case of the typical galls ap- 
pears to be a minute quantity of some 
irritating fluid or virus secreted by the 
female insect and deposited with her egg 
in the puncture made by her ovipositor 
in the outside park or foliaceous parts. 
This virus causes the rapid enlargement 
and subdivision of the cells affected by it 
so as to form the tissues of the gall. 
Oval or larval irritation also, without 
doubt, plays an important part in the 
formation of many galls. 
A certain relation is necessary between 
the stimulus and the plant, as evidenced 
by the limitation in the majority of cases 
of each species of gall insect to some one 
vegetable structure, still, it must be a 
quality of the irritant of the tissues rath- 
er than the specific peculiarities on the 
part of the plant affected that principally 
determines the nature of the gall. Thus 
the characteristics of the currant gall, 
Spathegaster baccarum, which occurs 
alike on the leaves and on the flower 
* Encyclopedia Britannica, 11th edition. 
