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WHY, WHKN, AND HdW TO SUMMER PRUNI; AND RF.SIJLTS TO EXPECT 



William .1. Lord and Duanc W. Greene 

 Depart men t of Plant and Soil Sciences 



Last year we discussed the results of our summer pruning 

 experiments (FRUIT NOTES 47(3) :l-6, 1982). In the article below 

 we have answered the following questions about summer pruning: 

 (1) why, when and how; (2) what results to expect; and (3) advan- 

 tages and disadvantages. 



Whj£. Recent results from England, South Africa, Europe, and 

 Massachusetts indicated that late summer pruning can restrict 

 growth, increase red color on fruit, increase leaf Ca, reduce 

 the incidence of bitter pit, increase fruit flesh Ca , and reduce 

 internal breakdown in storage. In England Preston pruned by the 

 established spur method. This involved the removal of strong 

 laterals not needed for new branches and shortening of weak ones 

 to 3 inches to induce spur formation. Laterals of medium vigor, 

 mainly on the tree periphery, were not pruned. Subsequently, 

 these were shortened to a spur, or removed when crowding occurred 

 or they became too large. Laterals from spur systems or induced 

 spurs were shortened to 1 inch. In Massachusetts, the trees were 

 summer pruned by removing all current season's shoots. Terblanche 

 et al. in South Africa removed all current season's growth of the 

 bearing units as well as excessive shoot growth. Only sufficient 

 shoots were left to serve as future bearing units. Utermark in 

 West Germany drastically reduced leaf area by removing growth 

 beyond the outermost fruiting spur on each branch. 



The summer pruning techniques that enhanced fruit quality 

 seem severe and time consuming, and contradictory findings have 

 been reported. Thus, our experiments were designed to compare 

 effects of summer pruning with winter pruning and to evaluate 

 methods that fruit growers might adapt. The experiments were 

 established on young bearing trees of: (1) Mcintosh on seedling 

 roots; (2) Cortland on M7a; and C3) Red Prince Delicious on MM106 

 rootstock. 



When and How to Summer Prune . August is the best time to summer 

 prune because of less regrowth than from earlier pruning. We 

 believe that the need to summer prune can be reduced with contain- 

 ment and corrective pruning during the winter to restrict tree 

 spread and height. The following procedures are suggested during 

 dormant pruning. 



1. Branches that crowd those of adjacent trees will have to be 

 removed or cut back to a weaker side branch. (Cuts made only 

 to maintain the desired outer profile of the tree compounds 

 rather than alleviates tree containment problems, Such cuts will 

 produce vigorous growth which by the end of the next growing 

 season may extend as far as the original branch was before 

 shortening, and may cause more shading within the tree than did 

 the original uncut branch.) 



