GROWING SEASON TEMPERATURES 243 



quality along the Penobscot River than in the middle states. Inci- 

 dentally he mentioned English gooseberries as succeeding better around 

 Bangor, Maine, than elsewhere. It seems probable that the cool sum- 

 mers of that section favored the best development of these fruits. 



The converse limitation is less generally understood but it is none the 

 less potent. Most varieties of apple have certain heat requirements for 

 the attainment of their best quality or indeed for their ripening. Cions 

 of the Baldwin, favored by a succession of mild winters in Aroostook 

 County, bore fruit which failed to ripen because it was arrested in its 

 development by cold weather while still green.^^ Shaw^'^ found marked 

 differences in Ben Davis grown in various sections, indicating incomplete 

 development in much of the northern apple growing section. The limits 

 of successful culture of many varieties are conditioned by the minimum 

 winter temperatures, thus rather obscuring the importance of suminer 

 heat but, as with other fruits, there seems to be some reason for consider- 

 ing winter hardiness in some cases to be affected by summer temperatures. 

 So far as climatological data show, the minimum winter and average 

 winter temperatures for Boston, Mass., and Columbia, Mo., are almost 

 identical, but their summer temperatures differ considerably. Winesap is 

 considered tender and unsatisfactory in Massachusetts while in Missouri 

 it is one of the best commercial varieties. Apparently the limitation is 

 set by winter temperature in the Mississippi valley and by summer 

 temperature, directly or indirectly, along the Atlantic seaboard. The 

 northern commercial limit of York Imperial crosses the Mississippi near 

 the southern Iowa border and the Atlantic coast in New Jersey. ^^^ Here 

 again the correspondence between the northern limits east and west is 

 better in summer temperatures than in those of winter. The same con- 

 trol is evident with Rome Beauty. 



Shaw^^^ concluded after extended study that a certain optimum 

 summer temperature may be assigned to each variety of apple, ranging 

 from 52°F. for Hibernal and Oldenburg to 67°F. for Terry and Yates. 

 As appears from Table 7 the temperature range of the chief commercial 

 varieties is somewhat more narrow. A considerable effect, however, on 

 the limits of commercial cultivation of apple varieties must be assigned 

 to summer temperature. 



Table 7. — Optimum Average Summer Temperatures for Leading Commercial 



Varieties 

 {After S/iaw)'") 



Baldwin 56°F. Yellow Newtown 60°F. 



Rhode Island 56 York Imperial 62 



Northern Spy 56 Grimes 62 



Wealthy 56 Stayman 63 



Jonathan 59 Winesap 64 



Delicious 59 Ben Davis 64 



