324 MANUAL OF FRUIT DISEASES 
referred to as pear-blight, blossom-blight, twig-blight, fruit- 
blight and blight-canker. Various combinations of these 
names are used. The term blight signifies a sudden killing 
of a part or all of the plant, and in case of fire-blight the blos- 
soms, leaves and limbs are so affected. 
The disease is of American origin, having first been known 
and described in 1794 from the Hudson River Highlands in 
New York State. Since its discovery fire-blight has appeared 
in the South and West, and about 1880 it was the chief topic of 
discussion in the horticultural meetings in the Middle West. 
For several years it was unknown west of the Rocky Moun- 
tains, but about 1900 it was described from California. The 
disease now has a very general range throughout the United 
States and southern Canada, but does not occur elsewhere. 
Fire-blight is the most universally destructive of all poma- 
ceous fruit diseases. The range and perennial nature of the 
host and the nature of the disease account for this condition. 
Being an epiphytotic disease, it may appear suddenly in a 
locality and rapidly cause severe injury or complete destruction 
to the pear industry of that section. Nursery-stock suffers 
severely, and often thousands of affected trees are ruined. In 
some cases entire blocks of pears are destroyed. Orchard trees 
may be killed in one season. In some years the attack sub- 
sides, but with the recurrence of favorable conditions the 
ravages are renewed. The disease is said to be generally least 
troublesome in the United States and in portions of Canada 
bordering the Great Lakes. But in New York and Michigan 
the outlook is sometimes discouraging. In the region south of 
these two states Bartlett pear-growing has been largely aban- 
doned. In the southern states the Kieffer, generally regarded 
as resistant to the disease, was once widely grown, but its culture 
has been discontinued, owing to the destructiveness of fire-blight. 
In California two-thirds of the Bartlett trees had been de- 
stroyed by 1908. 
