THE GEOaRAPHY OF FRUIT GROWING 625 



in the summer temperatures. Madison, Wis., has evidently sufficient 

 summer heat to satisfy the Baldwin's requirements; the difficulty in 

 growing Baldwin at this last point is known to be winter temperature. 

 So far as apple growing in the United States is concerned, then, there 

 are along the northern limit, two different factors operating, summer 

 temperature and winter temperature; the effects of the one sometimes 

 mask those of the other. However, there appear to be very few places 

 listed in the table where the Baldwin apple would suffer from lack of 

 summer heat. Data are presented in Tables 3 and 4 showing the mean 

 monthly temperatures throughout the year and the minimum tempera- 

 tures for the six winter months at a number of stations in the United 

 States. Except for the California and Alaska points, each station 

 included in the tables may be taken as representing fairly well a commer- 

 cial apple producing section. The figures afford an idea of the range in 

 mean and minimum temperatures within which apple growing is profi- 

 table and by inference, an idea of the temperature limits for the commer- 

 cial varieties. A comparison of these data with the records of the 

 leading varieties in the several districts represented, likewise affords a 

 fairly accurate measure of their particular temperature requirements 

 and this, in turn, may be used as a basis for judging their probable 

 suitability for sections where they have not been tried but where tem- 

 perature records are available. 



Averages are treacherous at times and caution should be observed 

 in their interpretation. Lewiston, Maine, shows the lowest mean winter 

 temperatures of any of the apple sections represented in Table 3. Never- 

 theless this region grows successfully several apple varieties which cannot 

 be grown in the Bitter Root valley, as represented by Missoula. Refer- 

 ence to Table 4 shows that the mean temperatures for Missoula conceal 

 a November minimum of — 20°F. as compared with plus 2°F. for Lewiston 

 and a January minimum of — 42°F. for Missoula as compared with 

 — 24°F. for Lewiston. Over a long period the amount of winter killing 

 around Lewiston is probably no greater than that around Spokane, Wash., 

 though Lewiston averages 8° colder in January and 10° colder in February. 

 The October and November means, however, are only 1° apart. Abso- 

 lute minima for Lewiston in October, November and January are actually 

 higher than those for Spokane (6°, 15° and 6°F. respectively). The 

 November temperatures, mean and minimum, seem particularly impor- 

 tant in relation to winter injury along the northern border of apple 

 growing. 



The total effective growing temperatures at Portland, Oregon, and 

 Portland, Maine, are practically the same and the same varieties of 

 apples attain an almost equal development in the two places. Appar- 

 ently in this case neither maximum nor mean summer temperatures in 

 Oregon nor minimum winter temperatures in Maine are limiting factors 



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