PRUNING— THE METHOD 433 



though tillage is thought to effect a root pruning seldom, some of the 

 more important effects of severing a portion of the tree's roots at different 

 seasons may well be noted. 



In the culture of dwarf trees of almost any kind, Rivers,^^ one of the 

 leading exponents of the practice, recommended an annual, or at least a 

 biennial, shortening of all the roots. In describing the operation he said: 

 "Open a circular trench 18 inches deep around the tree, 18 inches from 

 the stem, and cut off every root and fibre with a sharp knife. When 

 the roots are so pruned, introduce a spade under one side of the tree, and 

 heave it over so as not to leave a single tap-root; fill in your mould, give a 

 top dressing of manure, and it is finished. The diameter of your circular 

 trench must be slowly increased as years roll on; for you must, each year, 

 prune to within 1}^4 or 2 inches of the stumps of the former year. Your 

 circular mass of fibrous roots will thus slowly increase, your tree will 

 make short and well-ripened shoots, and bear abundantly." It is gen- 

 erally recommended that this root pruning be done in the late fall. The 

 major repsonse will then be evident the following spring and summer in a 

 reduced vegetative growth and an increased formation of fruit buds. 



Some conception of the dwarfing influence of continued root pruning 

 on apples grown on Paradise stocks is afforded by an investigation con- 

 ducted at the Woburn Experiment Station in England. In summa- 

 rizing their results, Bedford and Pickering^ state: "In one series the 

 trees were root-pruned every year, in another every other year, and in 

 a third every fourth year; actual lifting from the ground being adopted, 

 till they became too large for this to be done without excessive injury. 

 The check caused to the growth of the trees was apparent from every 

 point of view, and its extent may be gathered from the weights of the 

 trees when they were ultimately removed. Thus with the Cox, which 

 were removed after 15 years, the weights of those trees which had been 

 root-pruned every fourth year were only 43 per cent of those which had 

 not been root-pruned; where the operation had been performed every 

 other year, the weights were 7 per cent of the non-treated trees, 

 and with the yearly operation, 3 per cent; indeed, in the last case, the 

 trees had scarcely increased in weight since they had been planted, and 

 had been dead for several years before they were removed." These 

 investigators then state that root pruning is followed by increased crop 

 production, though usually this is not evident until the second season 

 after the operation. However, repeated root pruning so weakens the 

 trees that they soon fall behind non-treated trees in yield. Bedford 

 and Pickering conclude that "root-pruning is an operation which should 

 be practiced with extreme moderation, and only in those cases where 

 excessive branch-growth calls for stringent measures." The root 

 pruning investigations of Drinkard^® in Virginia led to practically the 

 same conclusions. He reported a greatly reduced shoot growth, with 



