7 



DOES SUMMER PRUNING OF MCINTOSH PAY? 



Duane W. Greene, Wesley R. Autio, and William J. Bramlage 



Department of Plant and Soil Sciences 



University of Massachusetts 



The uncertainties about the future of Alar* and the possibilities of 

 adverse results on animal feeding studies led many growers in 1986 to use no 

 Alar* or a reduced amount of Alar* last year. A number of suggestions were 

 made last year to help growers cope with reduced Alar* use, and summer pruning 

 was listed as one of the procedures available to growers to help alleviate 

 problems associated with the nonuse of Alar*. Last year a summer pruning 

 experiment was conducted at the Horticultural Research Center using mature 

 Mcintosh trees. The results of this experiment are reported here. 



There is a direct relationship between the amount of light a fruit 

 receives and red color development. Fruit that are exposed to direct or near 

 direct sunlight will develop red color early and the intensity of the color 

 will be great enough so that these fruit can be harvested as U.S. Extra Fancy. 

 Alar* has been indispensible to growers in controlling drop and retarding 

 ripening until fruit develop sufficient red color to be sold as U. S. Extra 

 Fancy. In the absence of Alar* fruit may fall to the ground before they 

 develop sufficient red color. If light penetration into the tree can be 

 increased by appropriate pruning techniques, fruit may develop red color early. 

 This early coloring would do two things. First, it would allow early harvest 

 of fruit that would have the potential for long-term storage. Secondly, it 

 would allow the harvest of a larger percentage of the crop as hand picked fruit 

 rather than as drops. 



A block of mature Mcintosh on M. 7 rootstock that received no Alar* in 

 1986 was selected, the summer pruning treatments were randomized, then half of 

 the trees were summer pruned during the 3^*^ week in August. Only 1-year-old 

 wood and unproductive wood were removed. It required about 25 minutes for one 

 person to summer prune each tree. The first harvest on these trees was on 

 September 10. 



Large cuts, particularly in the tops of trees, should not be made during 

 the summer. Falling branches, heavy with leaves and developing fruit, can 

 severely bruise fruit below. For summer pruning to be truly effective, large 

 thinning-out cuts must be made during the dormant period. These cuts will open 

 up a tree. The summer pruning further increases light penetration by removing 

 some of the current season's growth and unproductive wood. 



There were many positive effects following summer pruning (Table 1). 

 Fruit on summer pruned trees had more red color, considerably more of them 

 graded U. S. Extra Fancy, and a much larger percentage of the crop was 

 harvested during the first picking (September 10). Because a larger percent of 

 the crop was harvested the first time, there were fewer drops and more hand- 

 picked fruit from the summer-pruned trees. Summer pruning did not influence 

 the total yield on these trees. However, approximately 2 more bushels of fruit 

 per tree were harvested as hand picks rather than as drops. 



