400 SCIENCE PROGRESS 



the new wood which is thus made may rejuvenate the tree 

 and result in a healthy growth, which would never have occurred 

 had the old branches been left unpruned ; but in the case of a 

 tree already in a healthy condition the formation of new wood 

 to supply the place of that which has been cut away must 

 involve an extra tax being placed on the resources of the tree 

 and though the tree may do more work, the results will fall 

 short of those which would have been obtained without the 

 pruning. In other words, a young tree which is pruned heavily 

 every year must necessarily remain a smaller tree than one 

 which has not been pruned. 



Various plantations of different varieties of apple trees on 

 the paradise stock have been grown side by side at Woburn 

 under different systems of branch-treatment. The normal 

 treatment consists of light pruning every year, involving the 

 removal of about one-third of the length of each new shoot 

 formed during the season ; whilst in other cases the pruning 

 is hard, two-thirds of the growth being removed; in others, 

 again, there is no pruning. The trees are measured periodically. 

 The results leave no doubt that the less a tree is pruned 

 the bigger it becomes : the unpruned trees after five years 

 showed an excess of 33 per cent, in size over the moderately 

 pruned ones ; those which had been hard pruned showed a deficit 

 of 13 per cent. The differences naturally diminish as time 

 goes on, at any rate in cases in which the pruning is only 

 moderate ; for after ten years the unpruned trees showed an 

 excess of only 7 per cent, over the moderately pruned ones 

 and after fifteen years the difference was reduced to 2\ per cent. 

 The deficiency in size produced by the hard pruning, however, 

 shows no reduction; from the 13 per cent, after five years it 

 became 18 per cent, after ten years and was again 13 per cent, 

 after fifteen years. Figs. 3 and 4 represent average specimens 

 of an unpruned and hard-pruned tree of Bramley's Seedling 

 apple ten years after planting. 



It is found that the deficiency in size of the hard-pruned 

 trees is more marked as regards the height and spread than as 

 regards the girth of stem ; the former showed, after five years, 

 a deficiency of 21 to 24 per cent, but the latter one of only 

 9 per cent. : this is what might naturally be expected : therefore, 

 hard-pruning may be adopted as a means of making a tree 

 sturdier in proportion to its size than it would otherwise have 



