248 MANUAL OF FRUIT DISEASES 
(1) when the shoots are about six or eight inches long; (2) 
during or just before blossoming; (8) later applications are 
necessary only on very susceptible varieties or where irrigation 
is practiced when grapes are half-grown. Winter treatments 
are not generally commendable. The cost, including material 
and labor, varies from forty to fifty cents the acre for one treat- 
ment. Where it is necessary to treat vines for downy-mildew 
and black-rot, bordeaux mixture may be suitable for powdery- 
mildew. Liquid fungicides, however, are not as effective as 
sulfur dust, and in vineyards where this disease is particularly 
troublesome along with other diseases, it is best to follow the 
bordeaux sprayings with dust. 
The fungus shows preference for European vines; all Amer- 
ican varieties are less susceptible. These points are worth 
remembering in planting the vineyard where powdery-mildew 
is prevalent, 
REFERENCES 
Bioletti, F. T. Oidium or powdery mildew of the vine. California 
Agr. Exp. Sta. Bul. 186: 315-350. 1907. 
Reddick, D., and Gladwin, F. E. Powdery mildew of grapes and its 
control in the United States. Int. Cong. Vit. Rept. 1915: 117— 
125. 1915. 
Bioletti, F. T., and Flossfeder, F. C. H. Oidium or powdery mildew 
of the vine. California Agr. Exp. Sta. Cire. 144:1-12. 1915. 
Scribner, F. L. Report on the fungus diseases of the grape vine. 
II. The powdery mildew. U. S. Agr. Dept. Bot. Div. Plant 
Path. Sec. Bul. 2: 18-28. ‘1886. 3 
Jackson, H.S. Grape diseases. Powdery mildew. Oregon Crop Pest 
and Hort. Bienn. rept. 1911-1912 : 269-270. 1913. 
Scribner, F. L. The powdery mildew. U.S. Agr. Comm. Rept. 1886: 
105-109. 1887. 
Scribner, F. L. Distribution ena severity of the grape mildews and 
black rot in the United States. U.S. Agr. Comm. Rept. 1886 : 115- 
116. 1887. 
