GRAPE DISEASES 231 
In the United States it may be found in all grape-growing regions 
except in the state of California, where the conditions are highly 
unfavorable to it. In that state it is almost unknown, but its 
place is taken by the powdery-mildew fungus. 
Wherever found, this disease is of great importance because 
of the injury it produces to all of the parts above ground. 
There may result serious loss by the reduction in the amount of 
fruit ; and the leaves may be spotted to such an extent that they 
die. The very general range of the trouble makes it a constant 
foe, especially wherever susceptible varieties occur. All au- 
thorities are agreed that black-rot is the most serious fungous 
disease with which grape-growers generally have to contend. 
The amount of loss occurring each year varies with the season, 
there being an abundance of it in wet seasons and much less in 
dry ones. The disease is more troublesome in warm, humid 
regions than cool, dry ones. In North Carolina the heavy losses 
come within a week after blossoming-time, while in New York 
the greatest injury is incurred when the berry is one-half to 
two-thirds grown. In many sections of the country the de- 
structive nature of this disease has been responsible for the 
abandonment of grape-growing. In 1906 Michigan vine- 
yardists lost 30 to 40 per cent of their crops on account of black- 
rot; in Ohio in 1905 the loss is put at 30 per cent of the crop, 
meaning a loss of $28,500. The losses in many regions are 
practically total; this has been true in several states. A 
case is on record for 1906 where a large vineyard of 200 acres 
in New York did not yield enough grapes to pay for operating- 
expenses; the reduced yield here was due to the action of the 
black-rot pathogene. 
Symptoms. 
As a rule all the green parts of the vine may be affected with 
black-rot. The old portions and the fruit of rotundifolia 
varieties, like the Scuppernong, in southern United States are 
rarely attacked. 
