GRAPE DISEASES 
chiefly by the wind and rain. When 
these spores come in contact with the 
young and tender parts of the vine, un- 
der favorable conditions, they germinate 
and produce a slender tube, which pene- 
trates the tissue and may destroy it. 
This disease attacks the leaves and 
shoots, aS well as the fruit. It usually 
makes its first appearance on the leaves 
and young shoots, producing reddish- 
brown dead spots. The fruit may be at- 
tacked when young, but usually the dis- 
ease does not attract attention until the 
berries are half grown or more. Brown 
or blackish spots first appear: these 
spread and soon affect the whole berry, 
which becomes black and shriveled. These 
diseased berries remain attached to the 
vine, and their surfaces become covered 
with minute black pustules, which con- 
tain the summer spores of the fungus. 
During the winter and spring another 
form, called the winter, or resting spore, 
is produced upon these old, shriveled 
berries. These spores help to carry the 
disease over from one season to another. 
This fact would indicate the desirabil- 
ity of destroying, by burning, all diseased 
fruit, as well as leaves and prunings, as 
early in the spring as possible. 
Treatment 
This disease can be effectually con- 
trolled by thorough spraying with Bor- 
deaux mixture (4-8-50 formula). Five 
or six applications are usually necessary 
during the season, the first being made 
when the shoots are eight inches long. 
For the last one or two applications, 
some fungicide which does not stain the 
fruit should be used. Neutral copper 
acetate, one pound to 50 gallons of water, 
has been found the best non-staining 
preparation. The spray should be put 
on by nozzles giving a fine spray and di- 
rected by hand so as to cover all leaves 
and fruit. 
References 
Farmers’ Bulletin 284. 
Bureau of Plant Industry Bulletin 155. 
Cornell Bulletin 253. 
Cornell Bulletin 266. 
Cornell Bulletin 293. 
1123 
Colure or Dropping 
The raisin grape, Muscat of Alexan- 
dria, 1s subject to a blossom drop without 
setting of fruit. 
Failure of the blossoms to pollinate 
properly is assigned as the cause. 
The remedy is to plant occasional rows 
of other varieties such as Palomino, Per- 
runo, Beba and Berger. 
Reference 
California Experiment Station Bulletin 
197. 
Brown Ror. 
section. 
CALIFORNIA VINE Disease. See Mzs- 
cellaneous Diseases, this section. 
See Downy Mildew, this 
Downy Mildew 
Plasmopara viticola 
(B. & C.) Berl. & De Toni 
Downy mildew in certain seasons and 
in northern localities east of the Rockies 
sometimes causes more loss than black 
rot and is a close rival for first place 
among the fungous enemies of the grape. 
It attacks all the tender growing parts 
of the vine. Usually it is at first most 
noticeable on the foliage, producing 
greenish-yellow, irregular spots wpon the 
upper surface, which become reddish 
brown. At the same time there appears 
on the under surface of the leaf a thin, 
loose, white, downy growth, suggestive of 
hoar frost. This growth consists of the 
fertile fungous filaments bearing the sum- 
mer spores, which under favorable con- 
ditions are distributed by the wind and 
water to the berries and other parts, 
where they germinate, penetrate the tis- 
sues, and continue their destructive work. 
The young shoots are also frequently at- 
tacked and killed. 
The fruit, if attacked when young or 
only partly grown, shows first a brown- 
ish spot, and later becomes covered with 
the gray, downy growth of the fungus. 
This form of the disease is sometimes 
called “gray rot” by vineyardists. When 
the berries escape the disease until they 
are half grown or more it appears as a 
brownish or brownish-purple spot which 
spreads and soon involves the whole ber- 
ry. The affected fruit becomes soft and 
wrinkled and falls to the ground when 
