Apples. 13 



the changes are gradual, no harm need be anticipated, providing the pre- 

 ceding month of September was favorable for the ripening of the buds. 



Early apples, or summer ones, are more prolific, and more constant 

 bearers, than late or winter apples, caused, no doubt, by the trees having 

 shed their load of fruit in the early part of the season of growth ; their 

 whole work during two of the best months of the year being devoted to 

 preparing fruit-buds for the next year's crop. 



Heat is the principal working agent in producing fruit, as well as wood. 

 We can approximate very nearly the amount of heat required to produce 

 any given variety of apple. 



Nearly all apples blossom at or about the same time of the month in 

 corresponding latitudes. 



In the latitude of Boston, the average season is near the 25th of May 

 for the full blossom of the apple, with a mean temperature of 54.1° 

 Fahrenheit. 



The Early Harvest blossoms full on the 25th of May, having five days to 

 grow in the month of May. Five days multiplied by 54. 1° is equal to 270.5° 

 of heat. The mean heat of June is 62.8° X 50 days = 1,884°. Twenty- 

 five days in July to its ripening, with a mean heat of 69.1° = 1,726.5°. 



By this estimate, we find that it requires about 270.5° -|- 1,884° -}~ 

 1,726.5° = 3,884° of heat to ripen the Early Harvest. 



The Red Astrachan and the Sweet Bough, ripening about twelve days 

 later, require those twelve additional days of heat more than the above 

 variety. 69.1° of mean heat by twelve days = 829.2° -|- 3,884° = 4,713.2° 

 aggregate amount of heat required to ripen the Red Astrachan or Sweet 

 Bough. 



The Porter ripens about the 15th of September ; requires in May 270.5°, 

 in June 1,884°, i" July 2,170°, in August 2,048°, fifteen days in Septem- 

 ber 93.9° = 7j3I3° of heat to ripen after its time of blossoming. 



Here we see that the trees of the earlier varieties of apples produce 

 more fruit in a given number of years than those that require the whole 

 heat of the growing season to ripen their fruit. Those that require the 

 whole energy of the tree to carry forward a heavy crop seldom can have 

 perfect fruit-buds for a heavy crop until a season of rest. They become 

 alternate bearers ; producing heavy crops one year, barren the next year. 



