Performance of Mcintosh Apple Trees as 

 Affected by Rootstock 



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



Department of Plant & Soil Sciences, University of Massachusetts 



The New England apple industry depends largely on 

 the cultivar Mcintosh, which accounts for more than 50% 

 of the planted acreage. Although New England environ- 

 mental conditions provide an ideal climate for producing 

 very high quality Mcintosh, giving the area a niche culti- 

 var, market competition both within New England and in 

 other parts of the country has kept the wholesale returns to 

 Mcintosh growers just above the production costs. Grow- 

 ers therefore must pursue all means of reducing input costs, 

 enhancing cost efficiencies, and increasing crop value. 

 Rootstocks, particularly those which result in fully dwarf 

 trees, can affect all of these conditions by reducing some 

 management costs and by enhancing precocity, yield effi- 

 ciency, and coloring. 



A trial was established in April of 1985 to study the 

 relationship among various rootstocks with Mcintosh as 

 the scion cultivar. Summerland Red Mcintosh was included 

 on M.9/A.2 (Alnarp 2 as the root and M.9 as an interstem), 

 0.3 (Ottawa 3), M.7 EMLA, M.26 EMLA, M.7A, OARl 



(Oregon Apple Rootstock 1), and Mark in a randomized 

 complete block design with seven replications. Spacing 

 was 12 X 20 feet. Trees were not allowed to fruit until 

 1988, when in their fourth leaf. All trees were pruned mini- 

 mally; however, because of vigorous spreading, some had 

 to be containment-pruned before the end of the experiment. 

 Trunk cross-sectional area was measured annually, and tree 

 height and canopy spread were measured at the end of the 

 study. Yields per tree were assessed annually. Samples of 

 fruit were taken each year from 1989 through 1994 to as- 

 sess fruit size, and in 1991, 1993, and 1994, fruit were 

 sampled to assess average red color development. 



At the end often growing seasons, trees on M.7 EMLA 

 and those on OARl were the largest in the planting m terms 

 of trunk cross-sectional area, height, and spread (Table 1). 

 Trees on M.7A were similar in height and spread to those 

 on M.7 EMLA and OARl, but their mean trunk cross-sec- 

 tional area was significantly smaller than those on M.7 

 EMLA. Trees on M.26 EMLA and M.9/A.2 were similar 



Table 1. Tree size at the end of the tenth growing season (1994) and projected density of 

 Summerland Red Mcintosh trees on seven rootstocks.* 



Within columns, means not followed by the same letter are significantly different at odds 

 of I9;l. 



Fruit Notes, Winter, 1995 



