84 



POMOLOGY 



the entire top of the tree is pruned. When only a few shoots 

 are cut back, there is no measurable unbalancing of the 

 root system and top of tree and, therefore, no excessive supply 

 of water and soil nutrients, for the other branches of the 

 tree will make use of any additional amount. As a result, 

 no special stimulation is manifest and the branch which was 

 pruned is reduced in size in comparison with its former 

 rate of growth. 



The following experiment may be cited on this point: ^ 

 A shoot of equal length was chosen for observation on a 

 number of three-year-old nursery trees. This shoot was cut 

 back one-third its length in all cases, but with half the trees 

 under observation all the other branches were likewise 

 pruned back. The answer to the question here involved 

 will depend on whether the selected shoots will respond 

 similarly on both blocks of trees. The following data show 

 that, if the remainder of the tree is pruned, the selected 

 shoot makes a much greater growth than if it is the only one 

 which is cut: 



Table XIII 



NURSERY STAYMAN WINESAP, 1919 (AFTER CHANDLER) 



77. Heading-back versus thinning-out. — In discussing 

 the effect of pruning on the size and development of trees, 

 no differentiation was made between types, but rather the 



1 Chandler, W. H. Proc. Amer. Soc. Hort. Sci. 1919. pp. 88-101. 



