43 
been found in the State for at least hfteen years, In 1894, Prof. 
L. H. Bailey* wrote: '"Black rot was very prevalent in the vineyards 
situated on the banks of most of the lakes of Central New York. 
Some untreated vineyards lost from 50 to 75 per cent, of the crop 
from this disease, and even some treated vineyards showed a large 
amount of worthless fruit.'' In 1902, m^iny vineyards in Erie county, 
Pa., were visited by this disease to such an extent that losses of 
crop were reported ranging from one-fourth to one-half of the crop. 
At a conference of the grape growers of the district held on May 
5, 1903, at the call of the Hon. N. B. Critchfield, Secretary of Agri- 
culture of Pennsylvania, it was evident from the testimony given 
that very few grape growers knew the black rot disease well 
enough to say whether or not it had existed in the district at an 
earlier date than 1902. For several years previous a successful 
war was being waged against this foe in the vineyards of Ohio, and 
yet the destruction caused by it was so great that many vineyards 
were being uprooted to be replaced with other crops because of the 
discouragement of the proprietors. 
Symptoms of Black Rot. — The first appearance of black rot is 
made in July, from the 10th to the 25th, according to the cli- 
matic conditions. On the developing berries will appear livid brown 
spots, about the size of a pin head. These spots will increase 
in size gradually, and eventually the entire berry will be involved 
and have become a black-brown rotted berry, though still plump 
and firm. Where the original attack occurred, there will now ap- 
pear little black pimples and the surface of the berry begins to sink. 
The black pimples appear rapidly over more of the surface until the 
entire berry is spotted with them and the berry has become 
greatly shriveled. The rotted berry is dry and adheres to 
its stem, so that it may be removed only by breaking it 
off. Upon the leaves and young stems the fungus also 
makes its appearance at this time. On the upper surface of the 
fully developed leaves appear reddish-brown spots one-eighth to 
one-fourth of an inch in diat 'er, nearly circular. Wben these spots 
are a few days old little black pimples, like those referred to on 
the berry, will begin to appear. They are not so numerous on 
these spots as upon a similar area of the berry. These black 
pimples are known as the pycnidia of the fungus. They are the fruit- 
ing portions of the fungus plant. In them are developed the spores 
by means of which the fungus is propagated and is spread to other 
berries and leaves. 
The injury to the foliage by this disease is slight, but to the fruit 
it is most serious. Sometimes only one or two berries are de- 
stroyed, but when weather favors the spread of the disease, a half, 
•Bui. No. 76 Cornell Exp. Station. Tthara, NY. I _. _. 
