58 Farmers’ Bulletin 1220. 
the present name indicates, the disease usually appears on the fruit 
when the latter is nearly mature, and under favorable conditions con- 
tinues its development and destruction of the fruit after the grapes 
are picked. It also attacks the leaves and stems, but is most notice- 
able and injurious on the fruit. The first indication of the disease is 
the appearance of reddish-brown discolored spots (fig 65), which 
spread and finally extend over the whole fruit. The surface then be- 
comes dotted with dark, slightly elevated pustules, in which the 
spores are borne. At this stage of development the disease is not 
easily distinguished from the early stages of black-rot and bitter-rot. 
The berries do not 
shrivel up, however, 
as in the case of the 
black-rot, and usu- 
ally are easily de- 
tached from the 
bunch. The spores 
mentioned are pro- 
duced in large num- 
bers and serve to 
spread the disease. 
The fungus caus- 
ing this disease is 
closely related to 
that which produces 
the bitter-rot of the 
apple, and by some 
is regarded as_ the 
same; but no entirely 
conclusive  cross- 
inoculation experi- 
ments have yet been 
reported. The path- 
ologists of the De- 
partment of Agriculture have demonstrated by means of pure cul- 
tures of this fungus that there is another stage, producing spores very 
similar in appearance to those just mentioned, but borne in sacs which 
are inclosed in spore cases similar to those of the black-rot fungus. 
This spore form is of very infrequent or doubtful occurrence in 
vineyards, and is probably not an important factor in the distribu- 
tion of the disease. 
It is difficult to determine how much injury is done by this disease 
on account of the likelihood of confusing it with other fungous trou- 
bles and its usual occurrence with other diseases. It is quite generally 
distributed, and may cause more loss than is usually attributed to it. 
Fic. 65.—Grapes attacked by the ripe-rot fungus. 
