6/6 



NATURE 



[August 28, 19 13 



matter; the characteristics of the growth are mainly 

 dependent on the nature of the scion. 



During- removal of a tree from the nursery to the 

 plantation many of the roots are destroyed, and nearly 

 all of them are injured. The seat of growth of a 

 root is situated at the extreme tip of the root, the 

 power of multiplication being confined to a few meri- 

 slematic cells which are centred there, these being pro- 

 tected only by some layers of outer cells, known as 

 the root-cap, which are continually being rubbed off 

 and reproduced from the meristematic cells, as the 

 ront forces its way through the earth. The whole 

 root-tip is very minute, and when it is destroyed, 

 growth becomes impossible ; but there are certain cells 

 situated at intervals along the roots which are capable 

 of becoming modified and giving rise to new root- 

 tips, just as there are cells in the branches capable of 

 developing into buds if all the visible buds of a tree 

 are destroyed. 



When a tree is removed from the soil, most of 

 the root-tips will inevitably be broken off, and the 

 rest will become dried up by exposure to the air, so 

 thai the damage to the roots must be serious. But 

 the well-being of a tree depends on the balance be- 

 tween roots and branches, both of which supplv cer- 

 tain, but different, elements necessary for growth, 

 and this serious damage to the roots can only be 

 counterbalanced by damaging the branches to a corre- 

 sponding extent. This is done by severely pruning the 

 branches, cutting them back, as it is termed, to 

 about one-third of their length. The effect of omitting 

 this operation is often disastrous ; the tree mav be- 

 come permanently stunted, and even, in the case of 

 plums, which tend to bear heavily after moving, it 

 may be fatal. 



Though good horticulturists agree as to the neces- 

 sity of cutting back after transplanting, they differ 

 as to the time when this should be done. The results 

 of our experiments on a large number of trees show 

 that the time of cutting back makes little difference 

 to the ultimate size of the tree, so long as it is not 

 performed while the tree is in active growth. 

 If it is done in the summer, however, the 

 tie. receives a serious check, from which it 

 does not recover for at least the next seven 

 years. Deferring the cutting back until the follow- 

 ing winter does not give the tree any such check as 

 regards its growth, but it affects its fruiting. Such 

 deferred cutting back is generally followed in the 

 second year by vigorous growth, the tree making up 

 foi the absence of growth during the first year, and 

 it perseveres in this habit of growing in subsequent 

 years, when it ought to be growing and fruiting as 

 Well. 



Passing on to the question of the annual pruning 

 of a tree ; it is a common belief that the more vou 

 prune a tree the more it will grow. It seems fairly 

 obvious that, even if true at all, this must be true 

 only within certain limits; and, as applied to voting, 

 freely growing trees, it appears to be quite untrue. 

 Various plantations of similar trees at Woburn have 

 been systematically pruned to different extents during 

 the seventeen years since they were first planted, and 

 the photographs of average specimens from these 

 plantations are sufficient to show that, as regards the 

 genera! size, the trees which have never been pruned are 

 larsrer than those which have been pruned moderately, 

 and these again are larger than those which have been 

 pruned hard. What may be noticed as to the latter 

 is that it is a sturdier tree than that pruned mode- 

 rately, the trunk and main branches having gone on 

 swelling, while the extension of the branches was 

 prevented by the severe pruning. On the other hand, 

 the unpruned tree, as might naturally be expected, is 

 somewhat stracelv and not well shaped. 

 NO. 2 2^7, VOL. 91] 



Another experiment will illustrate the extent to 

 which pruning is opposed to growth. Four strictly 

 similar twigs, 30 in. long, were selected on the same 

 tree : one was not cut back, the others were shortened 

 to 24, 12, and 6 in., respectively. At the end of the 

 following season the weight of these twigs (taking 

 the average of many series) was in the proportion 

 of 562 : 310 : 178 : mo. and from every point of view 

 the growth of the twigs had been greater in proportion 

 as they had been less pruned (Fig. 1). In addition to 

 this, it was found that there were more fruit-buds, 

 and, therefore, a greater promise of fruit, the less the 

 twit;', were pruned ; the relative proportions of fruit- 

 buds in these cases were 314:238:165:100. That 

 this promise is actually fulfilled in practice is proved 

 by the records of the crops borne by plantations nf 

 similar tree-, which have for many years been pruned 

 to different extents. In one case these plantations 

 contained three different varieties of apples; it was 

 found that during the first five years, and also during 

 the second five years, the unpruned trees bore twice 

 as much, and 

 the hard-pruned 



ones little more .. 3t - 



th an half is 

 much, as the 

 trees which had 

 been pruned 

 mo derately. 

 These trees were 

 on the paradise 

 stock ; but the 

 same was found 

 to be the case 

 with apples cm 

 the crab stock, 

 fur we ha v e 

 another planta- 

 tion where 1 1 7 

 different varie- 

 ties of apples are 

 grown, four 

 trees on the one 

 stock, and four 

 on the other ; in 

 each case one- 

 half of them 

 have been 



pruned lightly, 

 and o n e-h a I f 

 heavily, and in 

 both cases the 

 crops from the 

 latter have beer. 

 former. 



What ha- urprised us i> that the heavier crops in 

 these cases have not 1" en accompanied by an\ s, rious 

 diminution in the size of the individual fruits. 



It is thus established as a fundamental principle, that 

 the less pruning there is, the more will a tree grow, 

 and the more fruit will it bear. But this does not 

 mean that we should dispense with pruning altogether. 

 The chief object in training a young tree is to make 

 it sturdy and well-shaped, so that it will be 

 capable of bearing a heavy crop when it comes to 

 full maturity; to effect this, the extension of the 

 branches must be c becked so as to give the stem and 

 main branches time to fill out, and occasionally a 

 branch will have in be removed altogether, either to 

 admit light and air into the tree, or to prevent it 

 rubbing against other branches. To what extent this 

 pruning should be carried, and for how long it should 

 be continued, must depend on the habit of the tree. 

 Instances of injury through the absence of pruning 

 may be seen in nearly any farm orchard throughout 



Fig.i. — Four similar shoots cut back to different 

 extents, showing the dilTerent growth made by 



than one-half of those from the 



