THE SUMMER PRUNING OF FRUIT TREES. 



489 



Woburn, and it is one, therefore, on which I wish to speak with con- 

 siderable diffidence. It is true that two or three of our experimental 

 plots, of eighteen bush apple trees each, have been subject to summer 

 pruning for the last thirteen years ; but two or three experiments are 

 quite inadequate for any complete examination of the subject ; whilst 

 other more extensive experiments have not been in progress long enough 

 to admit of any conclusions being drawn from them. The results, 

 however, which have been obtained at the farm, on the subject of 

 pruning in general, are calculated to throw some light on the more 

 special question of summer pruning. 



One of the general conclusions from our pruning experiments (which 

 have been dealt with at length in the Seventh Report) * is that, in 

 opposition to the popular opinion on the subject, the pruning of a 

 healthy, growing tree results in a diminution of the amount of new wood 

 formed, as measured either by the increase in size or weight of the tree, 

 or by the length or weight of the new shoots. The harder the pruning, 

 the greater is this diminution. As compared with moderately pruned 

 trees, those which had been continuously hard-pruned were nearly 

 20 per cent, smaller, whereas those which had been left unpruned were 

 about 20 per cent, larger. It certainly cannot be a matter of surprise 

 that the removal of any essential portion of an organism should, under 

 normal conditions, result in a check to the natural growth of that 

 organism, and this check should be all the greater if the part is removed 

 while it is still functioning actively — i.e. if the pruning is practised in 

 summer. Such evidence as exists, indicates that this is so, and shows 

 that pruning in summer checks the growth of the tree much more than 

 pruning at any other time of the year. The experiments which illustrate 

 this point most clearly are some in which very hard pruning, or cutting 

 back, was done on similar trees at different times in the year (see 

 Seventh Report, p. 37). Trees cut back at various dates during the 

 dormant season, November to April, all behaved similarly as regards 

 their subsequent growth, but when cut back in summer (the middle of 

 July) the amount of growth made by the end of the season was only 

 one-fifth of that of the other trees ; and the evil effects were not confined 

 to the one season only, for in the succeeding season these trees still 

 produced only three-quarters of the wood produced by those which had 

 been cut back while dormant, and they were otherwise deficient in 

 health and vigour. Cutting back quite early in the summer (middle 

 of May) produced similar but much less serious results. Other experi- 

 ments on cutting back young freshly planted trees are leading to like 

 conclusions, but the actual figures cannot yet be given. 



Ample evidence has been brought forward in our Seventh Report to 

 show that branch-pruning generally, when done in autumn, is inimical 

 to heavy cropping, but it does not follow that this will be so with 

 summer pruning ; indeed, the object of summer pruning is to increase 

 cropping ; and, on account of the check produced by it on wood formation, 

 it is easy to see that such a result should, or may, follow. The removal 

 of a portion of any shoot which is in a state of activity will divert the 



* Eyre & Spottiswoode. 1907. The Fifth Report, p. 36, deals more fully with 

 the results up to that date from the summer-pruned plots. 



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