Insect and Fungous Enemies of the Grape. 49 
they are not of sufficient economic interest to require much attention 
here. 
No attempt will be made here to treat of the nonparasitic diseases 
or those of obscure or unknown cause, such as the Anaheim or Cali- 
fornia vine disease, Little leaf, and Spanish Measles. These dis- 
eases are at present restricted to the European varieties and hybrids 
grown in the Pacific coast region, and no satisfactory methods of 
prevention or control are yet known. Their causes must first be 
determined by thorough research. 
Wie. 54.—The black-rot fungus: a, A portion of an affected grape, showing the 
pustules in which the spores are produced (slightly magnified) ; 6, a section of 
one of these pustules very highly magnified, showing the manner in which the 
summer spores are produced and discharged; c¢, a sac containing winter spores; 
d, single winter spores very highly magnified. 
BLACK-ROT. 
In the region east of the Rocky Mountains black-rot is the most 
generally distributed and destructive fungous disease of the grape. 
It does not occur in the arid regions of the West. It is caused by 
a parasitic fungus.2® It gains entrance to the plant by means of 
minute germs called spores. These are borne in small black fruiting 
bodies as shown in figure 54, a, b, and can not be seen with the naked 
eye. They are distributed chiefly by the wind and rain. Two or 
more forms of spores are produced, as shown in the accompanying 
illustration (fig. 54, c). When these spores come in contact with 
the young and tender parts of the vine, under favorable conditions, 
° Guignardia bidwellii (Ell.) V. & R, 
