8 MASS. EXPERIMENT STATION BULLETIN 320 



run over a rather dry gravelly knoll some twenty feet high which probably accounts 

 for the smaller growth. 



Table 3. — The effect of pruning on trunk diameter — Block K, Wealthy. 



(Millimeters) 



No Pruning 



1921 



Row C 57 



Row G 55 



Row K 62 



Row O 53 



1932 Increase 

 181 124 

 174 119 

 174 112 

 160 107 



Average.. 56.8 172.3 115.5 



Light Pruning 



Row A 59 174 115 



Row E 61 188 127 



Row 1 59 179 120 



Row M 71 181 110 



Average.. 62.5 180.5 118 



Moderate Pruning 



1921 



Row B 52 



Row F 61 



Row J 58 



Row N 66 



1932 Increase 



177 125 



184 123 



164 106 



179 



Average... 59.3 176 

 Light Pruning 



113 



116.8 



Average . 



58.3 180.5 122.3 



The old trees in Block O have been measured by taking the trunk circumference 

 instead of the diameter. The growth of these trees is shown in Table 4. 



Table 4. — The effect of pruning on trunk circumference — Block O. 



(Inches) 



L'npruned Lightly Pruned Heavily Pruned 



1925 1932 Increase 1925 1932 Increase 1925 1932 Increase 



R. I. Greening 59.4 64.9 5.5 59.5 04. S 5.3 58.3 (53.5 5.2 



Roxbury Russet 49.1 53.3 4.2 49.1 53.4 4.3 48.4 51.9 3.5 



Baldwin 54.1 59.9 5.8 55.2 60.9 5.7 58.7 66.2 7.5 



Gravenstein 64.0 71.3 7.3 59.9 67 1 7.2 56.6 61.7 5.1 



The heavily pruned Roxbury and Gravenstein seem to have made less and 

 Baldwins more growth than those lightly pruned or unpruned. With the R. I. 

 Greening the differences are slight. It will be noted that, in the case of the Bald- 

 wins, the heavily pruned trees were larger than the others in 1926 before the 

 experiment was started, while with the other three varieties the heavily pruned 

 trees were smaller. This suggests that conditions other than pruning have a 

 greater influence on growl h. Increases in circumference are more closely correlated 

 with previous size of the trees than with pruning treatment. 



It seems very doubtful that pruning as carried out in these experiments with 

 bearing trees has had much dwarfing effect. This is in harmony with earlier 

 experiments by the writer 9 where no dwarfing effect was found if the trees were 

 not headed back. 



Shaw, J. K. Head formation in apple trees. Mass. Alt. Expt. Sta. Bui. 238. 1927. 



