SUMMER PRUNING IS IMPORTANT FOR EARLY 

 HARVEST OF HIGH QUALITY MCINTOSH 



Duane W. Greene and Wesley R. Autio 



Department of Plant & Soil Sciences, University of Massachusetts 



Summer pruning is a useful technique for increas- 

 ing red color and allowing early harvest of Mel ntosh apples, 

 as we have previously reported (Fniit Notes 52(3):7-8). 

 Most researchers conclude that August is the best time to 

 summer prune. It is reasoned that at this time rcgrowth 

 following summer pruning will be minimal, there will be 

 little risk of encouraging winter injury, and it will not be too 

 late to enhance color development. The goals of our 

 research in 1987 were to confirm the benefits of summer 

 pruning and to evaluate the potential for expanding the 

 timing of summer pruning to include .inly. 



Dormant Pruning is Neccss:irv . Previously we 

 emphasized the need for proper dormant pruning to 

 achieve the maximum benefits from summer pruning 

 (Fm/VA'oto 53(1): 12-13). Large branches in the tops of the 

 trees that cause shading must be removed during the 

 dormant season, because removal during the summer 

 causes too much fruit damage and drop as cut branches fall 

 through the tree canopy. A program of limb rotation in the 

 tops of trees should be conducted in the dormant season to 

 maintain a conically shaped tree and to assure that there 

 are no major obstacles to light penetration into the tree 

 canopy. 



Summer Pruning Procedure . Summer pruning 

 cuts should maximize light penetration. (Jcneraliy, these 

 are made in the tops and on the periphery of the tree. 

 Specific suggestions are listed below. 



1. Remove vigorous, upright branches that will not be 

 productive. 



2. Remove weak, hanging branches that are shading 

 productive wood below them. 



3. Remove watersprouts; however, leave a sufficient 

 number with wide crotch angles to serve as potential 

 replacements for large branches in a limb rotation pro- 

 gram. 



4. Do not remove branches larger than 1 inch. 



5. Use thinning cuts rather than heading cuts, since 

 thinning cuts generally will result in less unwanted re- 

 growth. 



Research Results in 1987 . In June 90 mature 

 Mclntosh/M.7 trees were selected and distributed among 

 15 groups of 6 trees each. One tree in each group was not 

 summer pruned and served as a control. Each of the 

 remaining 5 trees in each group was summer pruned on 

 eitherJulyl, July 15, August 4, August 14, or September 1. 



The first harvest in this block was on September 

 15. Twelve percent more fruit were picked from summer 

 pruned trees at this harvest (Table 1). A random sample 

 of fruit taken immediately before harvest showed why this 

 effect occurred: summer pruning resulted in 10% more red 

 color and 30% more fruit making the U.S. Extra Fancy 

 grade (Table 1). There were no detrimental effects ob- 

 served due to summer pruning. Additionally, it appeared 

 to make no difference when the trees were summer pruned, 

 i.e. similar benefits were obtained from all treatments. 

 However, it should be noted that it took longer to prune 

 each tree as the sea.son progressed, 11 minutes per tree on 

 July 1 and 16 minutes per tree on September 1. 



The results reported here have important prac- 

 tical significance. The beneficial effects ofsummer pruning 

 on red color and packout again have been confirmed. 

 Additionally, more fruit may be picked in the early portion 

 of the harvest season when they have the maximum storage 

 potential. Furthermore, summer pruning may be done 

 equally well any time during the months ofJuly and August. 

 Therefore, growers may summer prune trees during slack 

 periods using existing help, or it may be advantageous to 

 bring in off sht>re labor early, specifically to summer prune 

 Mcintosh trees. 



