HEAD FORMATION IN APPLE TREES 



By J. K. Shaw 



As a result of experiment and research durina; the past ten or fifteen years, 

 our ideas of pruning young apple trees have undergone radical changes. These 

 changes have heen in the direction of less pruning, especially less severe cutting 

 back of one-year wood. Since the literature reporting these investigations has 

 been reviewed in many publications, no summary of previous work is attempt- 

 ed here. 



Accordingly an orchard was laid out, devoted to a comparison of six different 

 types of pruning, these being as well defined as the somewhat variable nature 

 of the trees permitted. The project was planned in the expectation of finding 

 how trees react to certain definite treatments continued year after year. It 

 was lioped that the information thus acquired would replace opinion with fact 

 in establishing a sound pruning practice. 



Outline of the Experiment 



The orchard of 600 trees was set May 10-15, 1916. The trees were all one- 

 year whips about four feet high. The varieties chosen were Baldwin, Northern 

 Spy, Rhode Island Greening, Mcintosh and King. The basis of selection was 

 partly conunercial importance and partly varying habits of growth of the 

 different varieties. 



There were two rows of 60 trees each of each variety, planted 10 by 11 feet. 

 Each experimental plot consisted of four trees, and each plot was five times 

 repeated with each variety. Thus for each type of pruning there were 20 

 trees e;ich of five varieties. In the spring of 1922, when the trees were six 

 years old, one half of the trees were removed. The other half of the trees 

 were continued to the close of the experiment in 1925. 



The soil was a sandy loam classified by the Bureau of Soils as belonging to 

 the Merrimac Series. It was of moderate fertility and had been more or less 

 neglected for several years before the orchard was planted. One end of the 

 area, comprising a little less than one-half the total, had been planted to 

 nursery trees for three years. The growth of the orchard trees on this part 

 was somewhat inferior the first season to that of the others planted on freshly 

 plowed sod land. In an effort to remove this difference a moderately heavy 

 application of manure was made to the poorer part in the spring of 1917. This 

 resulted in some improvement, yet the trees on this part average slightly 

 smaller than the others. This manure was the only fertilizer applied during 

 the period of the experiment. The soil was kept cultivated and a non-legiunin- 

 ous cover crop sowed annually. The growth of the trees has been very goofl, 

 as is indicated in the drawings reproduced herewith. 



At the time this experiment was started there had begun to appear evidence 

 that severe pruning was vmdesirable; hence the six types outlined below all 

 contemplated rather moderate pruning. 



1. Globular tree, headed back. The whips were cut back at planting at 

 various heights depending on the variety. The Spy trees were cut at 24 inches, 

 the Baldwin, King and Mcintosh at 30 inches and the Rhode Island Greening 

 at 18 inches. This last meant little shortening and with some trees none at all. 

 In succeeding vears these trees were thinned out each year and all one-year 



