CHAPTER XVIII 

 WINTER INJURY IN RELATION TO SPECIFIC FRUITS 



The discussion of winter killing to this point has been general. Any 

 species furnishing convenient illustrative material has been drawn on 

 and most of the types considered affect each species more or less; the 

 prevailing conception has been the tree in general rather than any specific 

 kind. There are, however, differences in the problem of hardiness as 

 it relates to the several species and detailed points of adjustment to 

 these differences. These can be considered more conveniently by dis- 

 cussing each fruit singly, evaluating for each the different types of injury 

 to which it is liable and indicating, wherever possible, the best means 

 of minimizing the difficulties. 



The Apple. — The apple is the most widely grown fruit in America 

 and is, at one point or another, exposed to practically every form which 

 winter injury can take; it seems, however, practically immune to some 

 of them. Aside from sunscald there is little or no evidence that the 

 apple suffers from those types of injury that are characteristic of late 

 winter, i.e., from warm weather followed by cold. Though killing of 

 fruit buds sometimes occurs it seems hardly probable that this is a kill- 

 ing of buds which have broken the rest period. At the time of the 

 Easter freeze of 1920 in the lower Missouri valley many varieties had 

 pushed their buds so far along that they showed pink. These varieties 

 of course suffered more or less but their killing constitutes a case of 

 damage to succulent tissues rather than of winter injury. Late blossom- 

 ing varieties, though the buds had swelled noticeably, were not damaged 

 by the drop to 14°F. Though this is not conclusive evidence it is sugges- 

 tive. A February freeze of — 7°F. in Georgia when some Japanese plums 

 were in bloom, worked serious injury to plums and peaches but caused 

 no damage to the apple. ^^'^ 



Whipple-"^ introduces clear evidence of fruit bud killing in Montana 

 and shows that little readily recognized evidence that the buds have been 

 fruit buds is left after they are killed. If the injury is confined to the 

 floral parts as Whipple has shown to be the case at times, the vegetative 

 parts grow and the casual observer concludes that the tree has failed to 

 form fruit buds and is going through an off year. It is, therefore, 

 possible that this killing may occur at times when it is not recognized. 

 Nevertheless it is safe to assume that fruit bud killing is comparatively 

 rare and that when it does occur it is not necessarily related to the 

 breaking of the rest period. 



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