PRUNING PRINCIPLES 89 



the limbs of many trees pruned in pyramidal form was 8.4 centimeters ; 

 pruned by removing only dead and crossed branches 9.5 ; and the 

 unpruned trees 11.7. Contrary to the general belief that regular 

 pruning seems to make stockier trees, these experiments indicate 

 that strong pruning prevents the rapid growth of the stem rather 

 than furthers it. 



85. Pruned Tomatoes. In West Virginia,* L. C. Corbett found 

 that tomatoes pruned after the fruit set produced a greater number 

 of ripe fruits to the plant up to September 1 than did unpruned 

 plants, but the total yield from each plant for the whole season was 

 less. Of the various methods of pruning tomatoes, the single stem 

 method gave somewhat earlier and larger fruits, but lessened the 

 total yield considerably. 



86. English experiments in apple pruning. At Woburn, England, 

 S. U. Pickering has conducted pruning experiments for 12 years. 

 He reports that trees dug up and weighed show that the less a tree 

 is pruned the larger and heavier it becomes. At the end of the 12 

 years those trees not pruned were 20 per cent heavier than the 

 moderately pruned ones, whereas the heavily pruned trees were 16 

 per cent lighter. Since the difference in weight between the un- 

 pruned and the moderately pruned trees is greatly in excess of the 

 wood removed by pruning, it is concluded that pruning does not 

 increase the actual size of the tree, but even results in less new 

 wood being formed. When similar branches on the same tree were 

 pruned to different extents, it was found that the less the pruning 

 the greater the number, length and weight of new shoots formed 

 and the increase in girth of the original branch. 



The reduction in pruning appears more marked as regards the 

 crop. With dwarf apple trees, during the first five years, the crops 

 from unpruned trees were more than twice as great as from those 

 hard pruned. These differences were increased during the second 

 period of five years, and at the end of the twelfth year the unpruned 

 trees yielded nearly three times as much as the moderately pruned 

 ones, while the hard-pruned ones had practically no crop at all. 

 (Only one variety was in fruit for comparison during the twelfth 

 year.) 



Similar results were obtained with trees of 53 and 80 varieties of 

 crab and paradise stocks, respectively. The trees were not allowed 

 to overbear, and it is claimed that the size of fruit obtained from 

 trees pruned to different extents was approximately the same, hence 

 the values of the crops were proportional to the weights. Confirma- 

 tive evidence of the antagonism of pruning to fruiting was obtained 

 by counting the fruit buds formed on similar branches of the same 

 tree, which was cut back to different extents. All of the above re- 

 sults refer to healthy, vigorous-growing trees. 



With dwarf apple trees 15 years old the author finds that hard 

 pruning results in an increase of the new wood formed, but that 



* Bulletin 49. 



