the results were too unpredictable and the practice too laborious 

 to be of value in commercial orchards. But, now that we have greater 

 density o£ plantings (trees per acre) than in the past, interest in 

 vegetative growth control has been renewed. Furthermore, we have 

 substantial acreage o£ trees on size-controlling rootstocks that are 

 easier to prune because they are smaller, and we have mechanical 

 pruning devices that m.ake pruning quicker. Delicious, the major 

 cultivar in the U.S., tends to make excessive growth and to be 

 unfruitful, and therefore needs growth restriction. And still 

 further, as we look for ways to improve the calcium nutrition of 

 apples we see reports from Europe indicating that summer pruning 

 can increase fruit calcium levels. There is, therefore, ample reason 

 to re-examine the applicability of summer pruning to commercial fruit 

 production . 



What is Summer Pruning? 



The term summer pruning alone means little and only tells the 

 season of pruning. It may mean nothing more than the removal of 

 water sprouts or performing dormant -type pruning during the growing 

 season as a means of tree training. Summer pruning could mean making 

 detailed cuts on current season's shoots throughout the tree, using 

 hand-held pruning tools, to restrict vegetative growth and induce 

 the formation of flower buds on young trees. It also could mean 

 removal of current season's shoots and/or 1-year-old wood on the 

 periphery of the bearing tree with hand-operated pruning tools or 

 a mechanical pruning device to restrict tree growth or increase fruit 

 c a 1 c i um . 



The object of our summer pruning investigations has been: (1) 

 to determine the vegetative and fruiting responses of young Delicious 

 and Cortland trees; and (2) to study its influence on quality of 

 fruit from Cortland and Mcintosh trees. 



Definition of Terms 



At this time a few terms used in this report should be defined 

 to avoid confusion that otherwise might arise in regard to their 

 meaning. Pinching will refer to the removal of only the tip of 

 current season's shoots. Heading will be the term used when cutting 

 current season' s shoots back to 4 to 6 mature leaves . Stubbing as 

 used here is to cut upright shoots on limbs about 1/4 to 1/2 inch 

 above their base, thus leaving a short stub. 



Axillary buds are borne in the axils of the leaves on current 

 season's shoots. When a current season's shoot is pinched or headed, 

 the axillary bud or buds directly below the pruning cut may produce 

 growth; these are referred to as axillary spurs or shoots . We arbi- 

 trarily classified any growth less than 1 inch long but producing a 

 whorl of leaves as being an axillary spur . When shoots produced more 

 than an inch of extension grovv'th they were classified as axillary 

 shoots . The tip of an axillary spur will become either a leaf or 

 flower bud. The terminal bud on an axillary shoot also will become 

 either a leaf or flower bud. 



