bettewFruit 



The Pioneer HoriicuUural Jourtjcil of the Pacific Northwest 



Entered as second-class matter April 22, 1918, at the Postoffice at Portland, Oregon, under act 



of Congress of March 3, 1879 



Volume XVI 



Portland, Oregon, March, 1922 



Number 9 



Pruning Studies in California 



By Warren P. Tufts 



Assistant Professor of Pomology, Uniz'ersity of California 



STYLES in pruning change, perhaps 

 not as often as do fashions in women's 

 wearing apparel, nevertheless, as one 

 travels from section to section, the fact is 

 emphasized that there is apparently a great 

 difference of opinion as to how fruit trees 

 should be handled in this respect. 



Although generalizations are dangerous, 

 the statement will be hazarded that the 

 California pruning method has, in the past, 

 been characterized by the severity of the 

 cutting. In some fruit sections of the West, 

 the opposite extreme of little or no prun- 

 ing may undoubtedly be found. 



The cutting of young trees is primarily 

 designed to influence the forms, however, 

 the functions of the plant are also pro- 

 foundly altered. "If you would have your 

 trees stocky, strong, and mechanically -able 

 to support heavy crops, prune your orchard 

 severely for at least four years after plant- 

 ing," has been the advice commonly heard 

 in nearly all deciduous fruit growing sec- 

 tions of California. 



Considered from the standpoint of plant 

 nutrition, it would seem that annually to 

 remove a large portion of the leaf bearing 

 area, which is the factory of food pro- 

 duction for the tree, in addition to the 

 loss of stored food reserves, would of itself 

 tend to weaken the life processes of the 

 plant. The fact, however, that orchard 

 trees have in almost all cases responded to 

 the heavy cutting with an exuberant vege- 

 tative growth the following season has mis- 

 led many to believe that annual shoot 

 growth alone is the true index- of the plant's 

 vigor. 



Is it not, however, more accurate to meas- 

 ure the tree's activity by the total weight 

 of wood laid down over the whole plant? 

 Experiments by the California Experi- 

 ment Station have shown that a very close 

 correlation exists between the diametef of 

 the trunk of a non-bearing tree and the 

 weight of both top and root. Any prun- 

 ing practice which gives a greater girth 

 in the young tree may be safely taken as 

 an index of a larger development over the 

 entire plant. 



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I Careful experiments and studies in | 



i fruning effects on deciduous fruit | 



I trees have been made in California \ 



I iri recent years, largely under the | 



I lead of Professor Tufts. These have \ 



I convinced this widely knozvn fomolo- | 



I gist and many others that certain \ 



I -pruning practices of the fast have not \ 



I been founded on sound frincifles. | 



I The findiftgs for instance, are against | 



i severe heading back of young trees | 



I and favor the "long system" of frun- | 



i ing, in general. These findings are \ 



I making a strong impression on Call- | 



I fornia growers of deciduous fruits, | 



I particularly where there is little or no | 



I irrigation. The report here given \ 



I deserves unbiased study by all readers \ 



I of Better Fruit and is of par- | 



I ticular import to those in unirrigated | 



I sections. | 



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The facts just presented perhaps rather 

 completely explode another tradition heard 

 in many fruit sections, namely, that heavy 

 cutting of the top, although perhaps re- 

 ducing the size of the above-ground parts, 

 nevertheless results in renewed and 

 strengthened root development. 



RESULTS of apple pruning investiga- 

 tions in England, Oregon, West Vir- 

 ginia and other sections show that the less 

 the tree is pruned the larger and heavier it 



becomes. In order to ascertain whether 

 these results hold equally well with other 

 deciduous fruits careful measurements were 

 made in the California Experiment Station 

 orchards at Davis, California. 



The experimental trees were planted 

 in deep, rich, alluvial loam soil, had not 

 been irrigated up to the time of these 

 measurements and, with the exception of 

 the pruning, had received identical cultural 

 treatment. Table No. 1 briefly summarizes 

 the results of the different pruning treat- 

 ments after one season's growth. 



In order to secure data on the stockiness 

 of branches as influenced by different 

 pruning treatments, measurements were 

 made on apricot trees which had been only 

 lightly pruned, others which had been 

 moderately, and still others which had been 

 severely pruned. All measurements were 

 made at a height of three feet from the 

 ground, the trees having been evenly 

 headed at the time of planting. The results 

 of these measurements are exactly in accord 

 with those made on the trunk. Certain 

 German investigators have reported similar 

 findings with apple branches. 



The figures of Table 2 summarize these 

 observations. 



TABLE n. 



INFLUENCE OF PRUNING ON 



STOCKINESS OF BRANCHES 



Average Increase in Circumference in Centimeters. 



Heavily Moderately Lightly 



Fruit Pruned Pruned Pruned 



Apple 8.4 Cm. 9.5 Cm. 11.7 Cm. 



Apricot 3.85 4.66 5.09 



TABLE I. 

 INFLUENCE OF PRUNING ON STOCKINESS OF TRUNK 

 •Average Increase in Circumference in Centimeters. 



Kind of Fruit 



Pruned 

 Severely 



Pruned 

 Moderately 



Pruned 

 Lightly 



Apricot — 



Cherry 



Peach 



Pear — 



Plum (Japanese) - 



Plum (European) 



Prune 



Averafe 



11.7 Cm. 



10.0 



12.0 



8.7 



6.3 



7.2 



6.2 



8.9 



12.6 Cm. 



11.2 



16.9 



9.1 

 10.4 



8.8 



7.1 



10.9 



15.3 Cm. 



12.3 



19.4 



9.7 

 11.3 



9.4 



8.4 



12.3 



