May, 1931] Studies in Economics of Apple Orcharding 9 



The curve shows beginning of bearing at 7 to 10 years, depending 

 upon the variety — a fact which is established beyond doubt. The 

 writers also feef certain that a tree will grow in capacity to bear at 

 rates corresponding rather closely with changes in growth rates as 

 observed with various plants and as described by Robertson, i Ac- 

 cordingly, a free-hand curve was drawn showing production to begin 

 at the seventh year and reaching a maximum of six packed boxes per 

 year at maturity, corresponding at intermediate points to the writers' 

 judgment and to a few data on actual yield which were available. An 

 approximate mathematical formula for this curve was then derived, 

 using a modification of the formulae of Reed and Holland. 2 The 



In New Hampshire much land suitable for orcharding is available 



at low cost. 



formulae of calculated growth curves are such as to show no decline; 

 yet it is obvious that as orchards grow old the bearing area and crop 

 production decrease. It was also felt by the writers that the calcu- 

 lated curve does not fit perfectly during the early years of production. 

 The curve as finally accepted is shown in the solid line of Figure 2. 

 the calculated curve being shown in a dotted line. Throughout most 

 of the bearing period, the accepted empirical curve corresponds exactly 

 to the calculated curve. 



Different varieties bear differently, the Mcintosh and Wealthy pro- 

 duce good crops at an early age, while the Baldwin and Spy mature 

 later. It would have been more accurate to draw vield curves for 



IT. B. Robertson. The chemical basis of growth and senesence. 389 pp. 

 Philadelphia and London 1923. 



-R. S. Reed and R. H. Holland. The gi'owth rate of an annual plant, 

 Helianthus. Proc. Nat. Acad. Sci. 5: 135-144. 1919. 



