Insect and Fungous Enemies of the Grape. 55 
spore cases are so small that they can scarcely be seen with the 
naked eye, but by the aid of a hand lens they can be easily observed. 
This is the principal fungous disease of the vinifera grapes on the 
Pacific slope. 
TREATMENT. 
For American varieties east of the Rocky Mountains, where black 
rot and downy mildew are usually prevalent, Bordeaux mixture 
should be applied as recommended for black rot (see spray schedule, 
p. 74). For vinifera grapes on the Pacific slope dusting with sul- 
phur has been found to be the most economic and efficient method of 
controlling this disease. Very fine sulphur, either 
ground or sublimed, should be used. It can be 
most effectively applied with a hand-dusting ma- 
chine such as shown in figure 77 or a similar type. 
A can with perforated bottom or a cloth sack is 
frequently used, but this method is less effective 
and not economical. 
Three thorough applications are usually sufh- 
cient to insure satisfactory results. The first ap- 
plication should be made when the new shoots are 
6 to 8 inches long; the second just before or during 
blossoming. If the first two treatments have been 
thorough, practically covering all the foliage, the 
third dusting should not be necessary except under 
weather conditions unusually favorable for the 
disease or with very susceptible varieties. 
If a third treatment is necessary, it may be made 
when the fruit is about half grown. 
ANTHRACNOSE. 
‘ 
Anthracnose *? has also been called “bird’s-eye py¢, 61.—Grape shoot, 
rot,” on account of the peculiar spots it produces — showing spots pro- 
upon affected grapes. Like most other diseases of — {Uced PY anthrac: 
the grape, it attacks the leaves and shoots, as well 
as the fruit. On the leaves it at first appears as minute, irregular, 
dark brown, slightly sunken spots, having a darker margin. These 
spots usually become lighter colored when old, and frequently crack 
or fall out, leaving irregular holes in the leaves. This disease pre- 
sents much the same appearance on the shoots as on the leaves, 
though the spots are frequently larger and more sunken (fig. 61). 
They also tend to run together and form irregular patches or cankers. 
The disease is most characteristic and conspicuous upon the fruit. 
The spots are usually brown at first and surrounded by a narrow, 
dark purplish margin; they increase in size and gradually become 
—go - 
82 Caused by Sphaceloma ampelinum De By. 
