PRODUCTIVE AND UNPRODUCTIVE 

 TYPES OF APPLE TREES 



STUDIES IN ORCHARD MANAGEMENT. IV.^ 



Karl Sax and John W. Gowen 

 Maine Agricultural Experiment Station 



IN AN apple orchard containing trees 

 of the same age and variety it is 

 usually possible to distinguish trees 

 which have different habits of growth. 

 The question naturally arises whether 

 these differences in growth habit are 

 correlated with differences in produc- 

 tivity. A study of the tree type and 

 yield of fruit was, therefore, undertaken 

 with 881 Ben Davis trees. The trees 

 are of the same age — about 28 years — 

 and during the period covered by this 

 investigation were free from serious 

 injury or disease. They were classi- 

 fied according to type or habit of 

 growth, and annual records were kept 

 of the yield and growth of each tree. 



In the present paper will be con- 

 sidered the characteristics of the vari- 

 ous types of trees, the relation between 

 type and yield and type and circum- 

 ference, and the factors which may 

 cause the different tree types. In 

 presenting these data the authors 

 wish to express their indebtedness to, 

 and appreciation of, the work of Dr. 

 Frank M. Surface, imder whose direc- 

 tion most of the data for this study 

 were collected. 



TYPES OF BEN DAVIS TREES 



A study of variation in the habit 

 and amount of growth of Ben Davis 

 trees reveals two principle contrasting 

 types, type 1 and type 3, and certain 

 intermediate types intergrading be- 

 tween the two main types. 



Type 1 is a large vigorous tree with 

 an open head. The branches are 



large and often drooping; and many 

 laterals are present with abundant 

 spurs. (See Fig. 1.) 



Type 3 is a rather small tree with 

 small upright branches. Its branches 

 are slender and have few laterals or 

 spurs. (See Fig. 3.) 



Between types 1 and 3 are a number 

 of integrading types whose position 

 in the series is determined by their 

 resemblance to the types described 

 above. Type 2 may be regarded the 

 center around which are grouped the 

 other types in the series. Type No. 2 

 is characterized by A vigorous growth, 

 spreading head, stout numerous and 

 drooping branches (Fig. 2). It differs 

 from type 1 in that it has longer 

 laterals and fewer spurs. Type 2 

 grades off to type 1 through types 2-1 

 and 1-2, the latter approaching type 1. 

 Similarly, the distance between types 

 2 and 3 is bridged by type 2-3 and 3-2 

 the former approaching type 2, the lat- 

 ter type 3. 



RELATION BETWEEN TYPE AND YIELD 



In general, trees of type 1 are the 

 most productive and the average pro- 

 ductivity decreases for the intermedi- 

 ate types as they approach type 3. 

 Type 3 is very unproductive, and even 

 in the most favorable year the trees of 

 this type bore an average of little more 

 than one bushel of fruit per tree. 

 The distribution of the yields of the 

 various types together with the means 

 and degrees of variability are shown in 

 Table 1. 



' Papers from the Biological Laboratory, Maine Agricultural Experiment Station No. 150. 



291 



