WINTER INJURY TO FRUIT TREES. 



PROFESSOR W. H. CHANDLER, POMOLOGIST, NEW YORK STATE COLLEGE OF 

 AGRICULTURE, ITHACA, NEW YORK. 



In preparing this paper I am assuming that the growers are 

 interested primarily in the losses due to the killing of the wood 

 of the trees during such winters as that of 1917-18. So while 

 the killing of buds or blossoms is more common, particularly in 

 case of peaches, cherries, some of the plums and apricots, I 

 shall confine myself largely to killing of the w^ood. 



Before describing the injuries that were to be observed fol- 

 lowing the winter of 1917-18, it seems w^ell to review briefly 

 the knowledge gained before that time through experimental 

 studies as to how plant tissues are killed by low temperature. 

 Some of the things that we knew were, first, that, unlike ani- 

 mals, plants possess no ability to maintain a temperature 

 above that of the air, that is, the temperature of the wood or 

 buds of the tree follows very closely that of the air temperature. 

 There are a few exceptions to this rule. Thus, in the case of 

 the trunks of very large trees, on account of the slowness 

 with which the heat is conducted through the tissues, the 

 temperature may remain several degrees above the air tem- 

 perature. This may be of considerable importance; thus it 

 is well known that the lowest temperature is likely to be just 

 before sunrise. The temperatures then begin to rise some- 

 what rapidly. If at that time the temperature of the tree 

 trunk should be several degrees above the air temperature, it 

 may thus be saved from reaching a killing temperature. Small 

 tree trunks on this account may sometimes reach temperatures 

 lower than the large ones and may therefore be killed when 

 the larger trunk, whose tissues are no more resistant, may 

 survive. 



