64 Farmers’ Bulletin 1220. 
in New York, Pennsylvania, and Missouri, and where present ap- 
pears to hasten the death of plants, especially those injured by the 
rootworm. 
Treatment.—This fungous rot can be prevented only by the de- 
struction of the insects which injure the root system and thus give 
the fungus opportunity to gain a foothold. (See control of grape 
rootworm, pp. 42-48.) 
OZONIUM ROT. 
There is a root-rot of a more serious nature, ozonium rot, preva- 
lent in and chiefly restricted to Texas, New Mexico, and Arizona. 
This is attributed to 
a fungus *® which also 
attacks the roots of 
cotton and a great va- 
riety of other plants. 
It is most destructive 
in the black waxy, 
clay soils, which are 
very poorly aerated. 
Plants attacked die 
suddenly, the leaves 
and fruit withering 
up in a day or two 
and remaining on the 
vines. 
remedy is known for 
this root-rot of the 
grape. Soil upon 
which other plants 
Fic. 71.—Crown gall on a vinifera grape. The large galls have died with the 
Bate formed near the crown of the plant just at the same disease should 
surface of the soil. c 
be carefully avoided 
in planting vines, and poorly drained, heavy soils should also be 
avoided if possible. 
SHELLING. 
The shelling or dropping of grapes from the bunches before ma- 
turity may be due to various causes. In certain localities in New 
York and Pennsylvania this trouble is rather serious some seasons. 
The cases which the department has had an opportunity to study 
have been found to be associated mostly with the dead-arm disease 
in its early stages. Unfavorable climatic conditions as well as un- 
balanced nutritive conditions also apparently tend to produce this 
trouble. 
®° Ozonium omnivorum Shear, 
T reatment.—No = 
