The Canadian Horhculturi^ 



Vol. XXXVI 



AiAY, 1913 



No. 



The Benefits of Winter and Summer Pruning Compared' 



By Dr. C. D. Jarvis, Conn. Agricultural College (formerly of the Guelph Agricultural College) 



PRUNING is a natural process. It 

 may be observed on both fruit and 

 forest trees. In the struggle for 

 existence the weaker branches, or those 

 unfavorably located, die and drop off. 

 An attempt, often successful, to heal 

 the wound takes place. The modern 

 practice of pruning is an attempt to as- 

 sist nature and to improve upon her 

 crude methods. 



The objects of pruning are three in 

 number. The primary one is to reduce 

 the struggle for existence among the 

 various parts of a tree so that the re- 

 maining portion may produce larger and 

 better fruits. Pruning, therefore, is a 

 thinning process, the beneficial effect of 

 which may be readily demonstrated by 

 the cutting out of about half the brush 

 from a negieciod apple tree. The pro- 

 cess includes the removal of dead or 

 diseased parts as well as of sujjerfluous 

 living branches. 



The second recognized object of prun- 

 ing is to control and modify the shape 

 of trees. Pruning, therefore, is a train- 

 ing process. It commences when the 

 tree is in the nursery now and may con- 

 tinue throughout its life. • 



Finally, pruning is practised on ac- 

 count of its effect upon the formation ot 

 fruit-buds and leaf-buds. The physio- 

 logical processes concerned in this are 

 not well understood, but it is well known 

 that pruning during the growing sea- 

 son produces an entirely different effect 

 from pruning during the dormant sea- 

 son. A heavy pruning of the top during 

 the winter tends to produce wood, be- 

 cause the same amount of root energy 

 is concentrated on a smaller top. The 

 pruning of the root has the opposite 

 effect, tending to lessen the production 

 of wood, because the same amount of 

 top receives a smaller supply of the 

 stored up energy of the roots and a 

 smaller supply of the soil water with its 

 plant food constituents. 



THE IDEAL IN PEUNING 



In the pruning of the apple tree there 

 are two distinct styles or ideals, the 

 central leader type and the open centre 

 type, each with its corps of adherents. 

 There are many supporters of the cen- 

 tral leader type among the westei n 

 growers, and they claim that a tree 

 pruned in this form makes a .stronger 

 structure and is not so likely to be 



•An acldr<»i delirered before the lCa«B»olitiaett« 

 Fruit nrowPTS' Association 



broken down by wind and heavy crops of 

 fruit. This is a strong argument and 

 cannot be ignored. A tree of this type, 

 however, is inclined to grow too high 

 and completely shuts out the light from 

 the centre of the tree. 



The open-centre type of tree is the 

 one most commonly found in the com- 

 mercial orchards of the east. For New 

 England, where the maximum amount 

 of sunshine is necessary to develop fruit 

 of high color, this seems to be the most 

 desirable type. If carefully grown and 

 properly trained, and if the trees are 

 not allowed to overbear, there is not 

 likely to be much trouble from the break- 

 ing of the branches. 



In order to develop a strong open- 

 centre habit, we must have a good nur- 

 sery tree to start wifh. We hear a great 

 deal nowadays about the desirability of 

 growing low-headed trees, and I am a 

 strong advocate of such practice, but 

 I do not believe in heading them so 

 low that there is no room for the proper 

 distribution of the main or scaffold limbs 

 of the tree. 



Many nurserymen are making a mis- 

 take in "rubbing" their trees too high; 



by this I mean that all the buds and 

 shoots are rubbed off from the yearling 

 tree to a point six or eight inches below 

 the point where the tree is headed in. 

 If the practice is to head a tree thirty 

 inches from the ground, the "rubbing" 

 should not extend more than twelve 

 inches from the ground, leaving a space 

 of eighteen inches for the proper distri- 

 bution of the scaffold limbs of which 

 there should be from three to five. These 

 should be fairly evenly spaced along the 

 central axis and no more than one 

 should be allowed to develop at the same 

 point. 



An apple tree is a wonderfully tract- 

 able object when handled properly. The 

 man who follows the ordinary practice 

 of severely pruning down the dormant 

 season only, is going to have trouble 

 for the more we prune at this season 

 of the year the more persistent the tree 

 l>ecomes. To encourage the develop- 

 ment of the weaker growing branches 

 and to check the persistence of the 

 stronger ones, it is necessary to do some 

 pruning during the growing season. 

 This subject will be discussed more fully 

 under the head of Summer Pruning. 



