THE McINTOSH DROP 11 



Table 6 — Block D, McIntosh Yields and Drops by Stocks (1934-1937) 



Stock Class Number of Average Annual Percent 



Trees Tree Yield (lbs.) Drop 



M. 16 vigorous 



Seedling vigorous 



M. 4 semi-dwarf 



Mcintosh vigorous 



M. 1 semi-dwarf 



M. 5 semi-dwarf 



M. 15 vigorous 



M. 6 semi-dwarf 



M. 13 vigorous 



M. 10 vigorous 



M. 12 vigorous 



♦Standard errors. 



The fruit drop varied from 47.2 percent to 23 percent with the different stocks. 

 These figures are based only on 50-pound yields or above and the populations 

 are relatively small. It seems noteworthy that such young trees have been beset 

 by so much preharvest dropping of fruit. However, the trees have grown rather 

 vigorously under a cultivation-cover-crop system. Perhaps the outstanding 

 feature of these data is the variation in dropping severity among the different 

 stocks without particular regard to their dwarfing effects on the scion. As these 

 stocks, however, are not randomized in the block, accurate interpretation is 

 difficult. Nevertheless, some of the variations in dropping behavior do seem to 

 refer to stock influence. As the trees grow older and yields increase, the extent 

 of the differences may be reduced. As was the case with Block E, there was again 

 some association between yield and drop. The most notable exceptions seem 

 to be with trees on M.12 and M.IO, which yielded fairly well yet lost relatively 

 little fruit from preharvest dropping. 



Influence of Seeds 



The importance of living embryos and seed development in connection with 

 the set and early growth of apples has been observed in many investigations 

 (1, 2, 3, 7, 8, 12, 13, 14, 19, 20, 25, et al.). In general, with apples the presence 

 of seeds is intimately associated with fruit development. The ovarian tissues 

 and the fleshy portion of the apple develop along with the enclosed ovules, and 

 important differences in this development are often associated with varying 

 seed number, growth, and distribution. That seed influence should be maintained 

 to some degree throughout the growing season seems plausible even though the 

 development of seeds in the early life of the fruit is probably of greater significance 

 than their presence later on. It is well established that fruit symmetry and size 

 are often affected by seed content and distribution. The author (28) has pub- 

 lished some data relative to the possible part played by seeds in delaying pre- 

 harvest Mcintosh drop. Table 7 summarizes this and supplementary data. 



