1040 



THE FRUIT INDUSTRY IN NEW YORK STATE 



dead and when present give one a clue to the starting point of the 

 cankers. In the case of some trees, especially Kieffers, certain 

 body cankers may affect only the outer bark, injuring the tree but 

 little or not at all. 



Dead sunken areas greatly resembling fire-blight cankers may 

 be due to winter injury, but it is impossible to tell in some cases 

 what causes the trouble. Winter injury 

 does not necessarily occur about the base of 

 a spur. It may occur along the west or 

 southwest side of trunk and branches and 

 even encircle them, or it may occur in the 

 crotch and at the base of the trunk near the 

 ground. 



During the growing season one can 

 always distinguish blight by the presence 

 of dead twigs, limbs, or blossom spurs, their 

 dead brown leaves contrasting sharply with 

 the glossy green of other leaves. At this 

 season the margin between healthy and 

 diseased bark on the limbs is not so evident. 

 The affected bark is of a darker color than 

 is normal and when cut into shows a reddish 

 brown discoloration, but there is no crack 

 between healthy and diseased tissues. Some- 

 times the reddish streaks of diseased tissue 

 may be found to extend for several inches, 

 or more than a foot, underneath healthy 

 tissue of the bark, and so they cannot be 

 discovered without having the bark above 

 removed. The infected tissue may extend 



into the roots, either showing on the exterior as a sunken dis- 

 colored streak, or lying concealed underneath unless the outer bark 

 is peeled away. 



The infected blossoms turn dark, become withered, and the 

 leaves of the blossom spur become dead and brown (Fig. 322). 

 The fruit may become infected at any stage in its growth. The 

 affected area has a water-soaked appearance, becomes soft and 

 brown, and later shrinks to a dark-colored mummy. During the 



FIG. 320. FIRE-BLIGHT 

 CANKERS ON LIMB OF 

 TREE. NOTE CRACK 

 AT MARGIN OF 

 CANKER 



