256 



POMOLOGY 



in the northern latitudes. The European plums, while 

 not tender, are usually not so hardy as other species and 

 are not widely grown so far north as New England and 

 Canada, although this again is 

 somewhat a varietal character- 

 istic. 



The buds of the peach are the 

 most tender of any of the tree- 

 fruits commonly grown in the 

 northern United States. Varie- 



ties vary markedly and no def- 



l^fe S^^^^H^^^I inite point of injury can be 



•* -■ ai^H^H^^H stated, but a temperature from 



18° to 20° F. below zero is likely 



to destroy all the fruit-buds and 



hence the crop. 



222. Injury to the woody parts 

 above ground. — While a loss of 

 the fruit-buds is a serious eco- 

 nomic factor, the injury that 

 may occur to the tree itself is 

 more destructive in its nature. 

 Winter injuiy to fruit-trees may 

 take sevei-al forms, some being 

 rather characteristic of one sec- 

 tion and some of another or all 

 forms may occur in a given 

 region. The following are the more important types of such 

 injury: killing of the terminal growth of the shoots; killing 

 of patches of tissue on the limbs or body of the tree; crotch 

 injury; "black heart"; collar-rot; frost-cracks; frost-cankers; 

 and sun-scald. 



223. The killing of the terminals on many kinds of fruit- 

 trees, even the more hardy ones, is common in a severe win- 



FiG. 35. — Winter injury on 

 trunk of a Baldwin apple 

 ■tree. 



