May 1908. j 



455 



SCIENTIFIC AGRICULTURE. 



WHY DOES PRUNING STIMULATE 

 FRUCTIFICATION ? 



By Geo. A. Pfister. 



The man who has constantly to deal 

 with plants, and intelligently watches 

 their development and life, will finally 

 be able to understand some of the deep 

 secrets which regulate their existence, 

 and which they disclose to him in their 

 silent language. 



If I have been able to understand this, 

 I think that amongst others, I have come 

 to explain the reasons why pruning stim- 

 ulates fructification. 



Whether what I am writing has been 

 observed or stated by others, I cannot 

 say. However, I am certain that I never 

 found it mentioned in any of the various 

 books and pamphlets on pruning or 

 fruitgrowing which have passed through 

 my hands. 



It is a proved fact, that trees which 

 have been well pruned— taking variety, 

 soil, and climate into due consideration — 

 bear more and better fruit for a longer 

 period of life. But if there is scarcely 

 any diversity of opinion upon this fact 

 amongst orchardists of thorough know- 

 ledge, it seems to ma that the reasons, 

 the causes of it, may be well open to 

 discussion. 



In fact all writeis agree that the leaf- 

 buds of a given shoot mostly develop 

 earlier into fruitbuds if the shoot is cut, 

 twisted, or pincked back, because 

 through this operation the flow of the 

 sap is checked, and in consequence of 

 the greater quantity of sap circulating 

 in less wood, the leaf buds develop sooner 

 into fruitbuds. I think this explana- 

 tion is not too clear, and perhaps even 

 contrary to the physiological laws; 

 because nature, which gives to every- 

 thing that lives, all the capacities con- 

 nected with life from the very beginning 

 of its existense, reserves the highest 

 faculty, which is the faculty of repro- 

 duction, for the mature organisms only ; 

 that is, for those which have attained 

 their full vigour, and takes it away from 

 them in their old age, when their vigour 

 is on the wane. 



Now if the forementioned transforma- 

 tion of buds was purely due to physical 

 laws, and supposing that this was the 

 only reason, the results ought to be con- 

 stantly the same- But in fruitgrowing 

 it is not always true that certain opera- 

 tions performed in a given way, will 

 always give the results which we expecc 

 from them. Allow me to explain ; In 

 the books on pruning we find that the 



bending and twisting of a shoot of a 

 pear tree has the result that from its 

 buds grow spurs, and in fact this will 

 happen almost regularly. Yet I have 

 often seen, that instead of spurs, one 

 developed into a vigorous shoot having 

 all the arpearance of a sucker, while the 

 other buds remain dormant. How is it 

 that tli is bud was not subject to phy- 

 sical effects of the changed circulation 

 of sap ? 



One of the rules in pruning is, that 

 from the purse of an apple or pear tree 

 will always grow dards or spurs, which 

 will bear fruit sooner than dards or 

 spurs which grow from a branch instead 

 of from a purse. I am ready to show 

 whomsoever desires to see, strong and 

 vigorous shoots grown from purses 

 which are not likely to bear fruit for at 

 least three years and even more. How 

 can this be explained if the abovemen- 

 tioned hydraulic law be true ? 



I have cut shoots of an apple tree 

 down to two-thirds of their natural 

 length, and as a result fruitbuds devel- 

 oped. Those shoots of the same tree, 

 however, which I pruned to one-third of 

 their original length, grew into wood, 

 one bud developing, the rest remaining 

 dormant. Here we have an example, 

 where the weakness of the plane was 

 greater and yet had the perfectly oppo- 

 site result; wood instead of fruic. 

 Where does the theory then come in ? 



These are some of the exceptions to 

 the rules which encouraged me to make 

 a modest critique to theories which are 

 almost generally accepted; theories, 

 which, however, are easily explained by 

 my theory. I do not deny that pruning 

 causes modifications in the circulation of 

 sap, but there must be other reasons 

 which cause the effects which we expect 

 from pruning. 



I think that the pruning is nothing, 

 but that we interfere, in a scientifically- 

 established way, with the physiological 

 integrity of the plant, injuring the same • 

 and to this injury— if not too great— the 

 plant answers with blossoms and fruits 

 trying to make sure of the preservation 

 of its own kind. 



I believe, that in nature, every being 

 be it animal or vegetable, has a responsi- 

 bility towards nature and creation, 

 which culminated in the preservation of 

 its own kind, in the struggle for exis- 

 tense. Not the struggle of the single 

 individual, but of the individual as part 

 of the whole class to which it belongs 

 Aud it is co me as if the plant knew, and 

 understood, that its existence is threa- 

 tened by the injury of the pruning knife, 



