THE PHILOSOPHY OF PRUNING 43 



effects may result from the considerable unbalance of the 

 plant when many branches are removed, these super- 

 fluous and unpruned twigs often afford a very useful 

 shelter or sun-screen to the inner parts of the top, and 

 they lessen the danger of over-pruning, by which the 

 nutrition of the tree may be injured. 



I have said that pruning increases vigor. Two trees of 

 Siberian Crab were set 25 feet apart near my house in the 

 spring. These trees are as near alike as any two apple 

 trees I have ever seen. I measured the growth on one 

 of these trees and found it to have been 745 inches. The 

 tree was then thoroughly pruned and 460 inches of wood 

 removed. Of this, 432 inches was new wood. The total 

 weight of this wood was 7^ ounces. 



The other tree was not pruned. During the third sea- 

 son the unpruned tree produced 118 new twigs, with a 

 total length of 1,758 inches, while the pruned tree pro- 

 duced 120 new twigs and made a total growth of 1,926 

 inches. The pruned tree, therefore, made 14 feet more 

 growth than the other and stouter growth also, a large 

 proportion for a tree only three years set. In other words, 

 a tree from which about 40 feet of branches had been cut 

 bore at the end of a single season 14 feet more wood than 

 a similar tree which had not been pruned. Aside from 

 the greater growth which this pruning induced, the ex- 

 periment shows in common with all similar ones that 

 it is impossible to injure trees by what is called a shock. 



It is often said that the time of the year when pruning 

 is performed influences the amount of growth [and] that 

 pruning in winter makes -wood and pruning in summer 

 makes fruit (83, 95, 97, 107, 108, 109). Certainly winter 

 pruning makes more wood than summer pruning does 

 in the current year, because the season's growth is nearly 

 or quite completed when the summer pruning is per- 

 formed. 



44. Why pruning is not injurious, I have said that 



