THE RELATION OF CLIMATE TO POMOLOGY 225 



The hail marks on the 

 fruit injure its selHng 

 quahty and indeed may 

 break open the skin, 

 thus encouraging rapid 

 deterioration. In some 

 sections it is not un- 

 common to find an 

 entire fruit crop de- 

 stroyed. (Fig 30). 



Serious injury may 

 also occur to the tree 

 itself, the healed scars 

 often resembling some- 

 what the work of the 

 tree cricket (Oecanthus 

 sp.) or cicada (Tibicen 

 septendecim). 



196. Continental ver- 

 sus marine climates. — 

 The climate of the in- 

 terior of the northern 

 sections of the United 

 States and Canada is 

 nnich more severe than 

 is the marine climate 

 on the same parallel. 

 This difference is pri- 

 marily due to the fact 

 that the specific heat 

 of water is much higher 

 than the materials of 

 which the earth's sur- 



FiG. 30. — Apple tree injured by hail 

 storm. Note abrasions of bark and 

 partial defoliation. 



