OBSERVATIONS ON THE CALIFORNIA VINE DISEASE 113 
author did not advance any opinion as to the nature of the 
disease. 
Pierce’s important memoir! on the California vine disease ap- 
peared in 1892 and contains many facts and figures of interest. 
In describing the disease he says: “In the majority of diseased 
vines, although not in all varieties, the leaf presents distinct char- 
acters. They may be mentioned as constitutional and localized 
characters.’ 
The general, or constitutional effects are “due to a failure in 
the formation of chlorophyll, or degeneration of that once prop- 
erly formed, in those portions of the leaf supplied by the finer 
spiral vessels. These general effects are found to some extent 
in nearly all varieties. . . . 
“Тһе localized effects upon the leaf are most clearly seen in 
the white varieties, and are especially distinct in the Muscat." 
The leaves become more or less covered with yellow spots "in 
that part of the parenchyma supplied with the finer spiral vessels. 
These spots are often well defined, the outline being very sharp 
and distinct. . . ."? j 
“Тһе cane usually becomes bare of leaves before the wood 
is properly ripened. Тһе end of the cane, being last to ripen, is 
most immature, and soon after the leaves fall the unripened parts 
turn black and become dry. This progresses more rapidly and 
the dying is more complete when the leaves drop early... . . The 
peculiar and unequal ripening of the cane is very marked."* f 
In the roots “among the first signs of disease is а dis- 
coloration and shrinkage in diameter of the finer root fibers, the 
root hairs and cap. This progresses until the tissue begins to 
decay. . . . The root, at last becoming wholly rotted, passes into 
a brown, loose, amorphous mass," 
The fruit of diseased vines is markedly affected. “If the first 
attack of the disease be violent the grape will sometimes fall from 
CN 
1 Pierce, N, В. The California vine disease, U. 5. Dept. Agr, Div. Veg. 
Path. Bull. 2. 1802. 
* Loc. сі, 41. 
