4 MASS. EXPERIMENT STATION BULLETIN 372 



Importance of Size Increase of Apples 



The importance of delayed abscission is fairly well understood by most growers. 

 Not only is the loss due to bruising lessened and the size, color, and quality en- 

 hanced, but the actual bushel yield may be increased. An apple usually con- 

 tinues to increase in size as long as it remains attached to the spur. The data 

 in Table 1 show this relationship. 



Table 1— Size and Crop Increase of McIntosh Apples, 1937 

 (Tree B-7) 



*V^4/3 71" a-b (a^cross radius. b=length radius) 



From these figures — and there are many others that show the same trend — 

 it is clear that the apples continued to grow in size into October. The time limit 

 actually is determined not by date but by the arrival of cold weather. The 

 columns giving the computed number of apples per bushel and the approximate 

 yield per acre show the advantage to the grower of extra days and weeks of 

 continued fruit development on the tree. The increase from 291 to 406 bushels 

 per acre means a 40 percent gain in yield. There are few practices which give a 

 better return. It should be pointed out that this result might have been less 

 striking had the full crop remained on the tree. That is, after any drop there may 

 be an exaggerated increase in the growth of the fruits remaining, as a result of 

 increased supplies of nutrients and especially of water. However, it does stand to 

 reason that in most cases a real delay in the normal Mcintosh drop would prove 

 very profitable from the standpoint of crop increase. Furthermore, our results 

 at Amherst show that late picking of Mcintosh usually results in increased storage 

 life of the fruit. This is in line with recent findings in New Hampshire (23). 



