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. 



