2 
Journal of Agricultural Research 
Vol. XXVII, No. V 
INCREASE IN SIZE OE THE ERUIT 
The data on increase in size of apples, particularly during the latter 
part of the growing season, are extremely meager. Whitehouse (27) 3 
measured the longitudinal and transverse diameters of Grimes apples 
at intervals, and found a steady increase in size from early June until 
September 20, when the last records were made. Actual diameter in¬ 
crease was somewhat less during the late season, but volume increase 
was very rapid. Curves based on Whitehouse’s data are shown in Figure 
1. In Figure 2 are shown measurements on diameters of 50 Winesap 
apples at Arlington, Va., during the summer of 1919. 4 Since the volume 
of the fruit increases approximately as the cube of the diameter, the 
second curve has been calculated to show the comparative increase in 
volume. 
Fig. i.— Increase in diameter of Grimes apples, Corvallis, Oreg., in 1915, after data by Whitehouse. 
The season of 1919 at Arlington had a very heavy rainfall in July, 
somewhat less than normal in August, less than half of normal in Septem¬ 
ber, and a heavy rain on October 1. It will be noted that there was a rapid 
increase in size from July until August 21, with only slow growth until 
September 19. A very rapid growth occurred between September 19 
and October 10, most of which probably occurred after the heavy rain 
of October 1. No frost occurred in October. 
These data indicate that if there is moisture available a large increase 
in size may occur very late in the growing season. There is much need of 
further investigations to determine how late this growth will continue 
under various conditions. Quantity of fruit on the tree as well as soil 
moisture will markedly influence the rate of increase in size. The size 
3 Reference is made by number (italic) to “Literature cited, ” p. 36 -38. 
4 The authors are indebted to L. A. Hawkins, physiologist, and L. B. Scott, pomologist, Office of Horti¬ 
cultural Investigations, for these data. 
