growth rate declined. In Maine, trees in Mark grew 

 more vigorously than the other trees in the first two sea- 

 sons, similarly to trees on 0.3 or M.26 EMLA in the 

 next two seasons, and similar to those on B.9 in the 

 fifth season. Trunk cross-sectional area of trees on 

 Mark, 0.3, or M.26 EMLA were similar and signifi- 

 cantly greater than that of trees on B .9 at the end of the 

 fifth season. 



Trunk growth also varied somewhat with scion cul- 

 tivar (Figure 2). By the end of the fifth growing season 

 in Massachusetts, Rome trees were larger than Empire 

 or Golden Delicious trees. Jonagold trees were inter- 

 mediate in trunk cross-sectional area. Although not 

 comparable statistically, Mcintosh trees were similar in 

 size to Golden Delicious trees. In Maine, there were no 

 significant differences among scion cultivars with re- 

 spect to trunk cross-sectional area after five growing 

 seasons. 



With respects to 

 tree height after five 

 growing seasons (Fig- 

 ure 3), trees in Massa- 

 chusetts on M.9 

 EMLA, B.9. 0.3, or 

 M.26 EMLA were 

 similar and signifi- 

 cantly taller than those 

 on Mark. In Maine, 

 trees on M.26 EMLA 

 or 0.3 were the tallest, 

 followed by those on 

 Mark. Trees on B.9 

 were the shortest. 

 Scion cultivar did not 

 affect tree height in 

 Maine, but in Massa- 

 chusetts, Rome trees 

 were taller than all 

 other trees. 



Canopy spread 

 was affected by root- 

 stock in both locations 

 (Table 1) and was very 

 closely related to dif- 

 ferences in trunk cross- 

 sectional area. Specifi- 

 cally, trees on 0.3 or 

 M.26 EMLA had the 

 greatest spread in Mas- 



sachusetts and those on B.9 or Mark had the least spread. 

 In Maine, canopy spread of trees on Mark, 0. 3, or M.26 

 EMLA was similar and significantly greater than that 

 of trees on B.9. Scion cultivar did not affect spread in 

 Maine, but in Massachusetts, the canopy spread of 

 Empire trees was significantly greater than of other scion 

 cultivars. 



Yield can be measured in various ways (Figure 4): 

 per tree, per trunk cross-sectional area, or per acre. Per 

 tree in Massachusetts, those on M.9 EMLA, B.9, Mark, 

 or M.26 EMLA yielded similarly for the period from 

 1992 through 1994. Only trees on 0.3 yielded more. 

 In Maine, trees on Mark yielded the most and those on 

 B.9 or M.26 EMLA yielded the least over the same 

 period. In Massachusetts, Rome trees yielded the most 

 and Empire trees yielded the least. In Maine, all scion 

 cultivars yielded similarly per tree. 



Table 1. Measured canopy spread and calculated tree densities of five rootstocks 

 and five scions in Massachusetts and Maine. In-row spacing was calculated as 80% 

 of the tree spread after five years, and seven feet were added to the in-row spacing 

 to obtain the between row spacing.* 



Within rootstock or scion and within column, means not followed by the same 



letter are significantly different at odds of 19:1. 



Mcintosh data from Massachusetts were not compared statistically, since trees 



were not replicated within the experiment, but were planted as part of a guard 



row. 



Fruit Notes, Spring, 1995 



19 



