PT. IV. 



PRUNING AND THINNING. 



187 



To grow valuable timber, we should not only aim To grow 



at a maximum lieig-ht of branchless stem, but a maxi- timber 



^ ^ maxim 



mum head on a maximum height of branchless stem ; 



girthing of the stem. 



For pruning trees to o;row to their greatest pos- Kuiesfor 



^ ^ ^ . ^ ^ . pruning f 



sible height, the rules are simple, and they are appli- i^eight. 

 cable alike to the nursery plant and to the largest 

 timber-tree : Keep a clear leader. Cut off all 

 branches large enough to compete with the stem, 

 or which grow parallel to it. Shrive the stem up 

 one-third of its height. Cut all close to the stem. 

 With the above exceptions, a tree cannot have too 

 many branches, as the returning sap of each contri- 

 butes to the growth in girthing of all that part of the 

 stem which is below it, and to the growth of the root 

 both in length and girthing. But pruning, like thin- 

 ning a plantation, cannot be too gradual. It should 

 be annual. 



A well-placed but over-large branch should be 

 curtailed where it turns up, or where it forks, or at 

 the foot of a shoot. It is bad pruning to leave a 

 dead stump with no growth beyond it, whose de- 

 scending sap shall deposit over the scar. 



In timber-woods and in plantations, the trees 

 should stand close enough to discourage the growth 

 of many side-boughs, or of any large ones. As the 

 side-boughs are gradually and annually overgrown, 



valuable 



