October 



SCIENTIFIC AGRICULTURE 



43 



The Relation of Pruning and Fertilization to Fruit 



Bud Formation 



By M. B. DAVLS. 

 Assistant Horticulturist, Central 

 Expel imental Farm. Ottawa. 



Horticultural science is to-day making 

 rapid strides in the solution of problems 

 upon which light has long been wanting. 

 Scientific research is unearthing a wealth 

 of material, much of which offers practical 

 solutions or at least suggestions for some 

 of the difficulties in profitable orchard 

 management. 



Pruning practices to-day a:e radically 

 different from those practised in the past, 

 and the new recommendations are based 

 on experimental results. The much dis- 

 cussed fertilizer problem is now Ijeing 

 studied from a plant physiological and 

 biochemical standpoint. Together with 

 external observations this has enabled us 

 to see this problem in an entirely new- 

 light, and although definite rules cannot 

 and perhaps never will be made on ac- 

 count of differences of location, many help- 

 ful and suggestive recommendations have 

 been the outcome. 



Fruit bud formation is another phase of 

 study recently investigated by several men 

 among whom Rol)erts of Wisconsin is 

 l)robably the most recent. 



Between pruning, fertilization and fruit 

 bud formation or fruitfulness is a close re- 

 lationship, and to fully understand one, it 

 is necessary to have a knowledge of the 

 others. 



The present article is intended to review 

 and bring up to date our knowledge of 

 pruning, and fertilization and its relation 

 to fruitfulness or fruit bud formation. 



Xot many years ago, it was a common 

 practice in the care of the young orchard 

 to head or cut back annually, regardless of 

 the condition of the tree. In fact, this 

 principle in a more or less modified man- 

 ner was extended to older trees in bearing. 



Some few years ago we cautioned against 

 indiscriminate heading back or butchering 

 of trees, but advised that for the first few 

 years of a tree's life, heading back was 

 necessary, especially with varieties tend- 



ing to produce long grbwtlis, with few 

 laterals. 



At the Vineland Experiment Station un- 

 pruned trees have yielded slightly better 

 than trees pruned. But trees pruned liglitly 

 in late summer have yielded almost as well 

 as the unpruned, and have the added ad- 

 vantage of being in better shape for future 

 performance. In fact, the unpruned t ees 

 if left indefinitely will reach a condition 

 where drastic treatment will be necessary 

 to relieve the congestion and to renew the 

 fruiting surface of the tree. 



At Ottawa, on young trees we have 

 found that no pruning has given as good 

 total growth as either spring or summer 

 heading back, accompanied by a larger 

 girth measurement. Where severe head- 

 ing back was practised, the girth measure- 

 ment was much less than in the unpruned 

 plots and the trees presented a less vigor- 

 ous appearance. 



Where light heading l^ack practised for 

 the first three years was adopted, the com- 

 parison between trees pruned and un- 

 pruned showed Utile difference in favour 

 of the unpruned, but those trees which had 

 been pruned were <jf decidedly better 

 shape and in better condition for future 

 work than the ones where pruning had 

 been neglected. 



These results have simply justified our 

 general orchard practice of years past, viz., 

 to prune during the first few years of a 

 tree's life with the express purpose of ob- 

 taining a desirable amount of groAvth 

 placed where we want it. 



In the case of some trees this will re- 

 quire considerable cutting out and some 

 cutting back for the first three or four 

 years. In other cases, it will require very 

 little wood removal, but in all cases the 

 trees should be attended to annually. 



Although in the light of modern re- 

 search we would say, "prune only as miich. 

 as is necessary to produce a tree of de- 



