20 30 40 60 



Trunk cross-sectional area 



Figure 1. Trunk cross-sectional area (cm') of Gala trees on several rootstocks in 

 the Massachusetts planting of the 1994 NC-140 Apple Rootstock Trial. 



It included Gala apple on 17 

 dwarfing rootstocks. Tree size 

 (measured as trunk cross- 

 sectional area), the number of 

 root suckers, yield, and fruit 

 size are assessed for each tree 

 each year. Cumulative data 

 from the first seven growing 

 seasons of the Massachusetts 

 planting of this trial are 

 included in this article. 



Trunk cross-sectional area 

 is a universally used method to 

 compare tree size of different 

 treatments. It relates directly to 

 the size of the canopy, and 

 therefore allows a rough com- 

 parison of relative planting 

 density. Even though all of the 

 rootstocks included in this trial 

 are considered dwarf, the trunk 

 cross-sectional area varies 

 greatly, from 6.9 cm- for trees 

 onP.22 to61.8 cm- for trees on 

 V.l (Table 1, Figure 1). These 

 results show that P. 22, M.27 

 Technical Committee evaluates fruit-tree rootstocks EMLA, B.491, P. 16, and B.469 likely are of little value, 

 throughout Nortli America. A recent trial was established in except with the very most vigorous varieties. Even with 

 1994 at about 25 locations in the United States and Canada. Gala (a relatively vigorous variety), these trees undoubtedly 



will "runt out" before the end of 

 the trial. On the other end of 

 the spectrum, V.l produces a 

 tree larger than does M.26 

 EMLA, and could be moved to 

 the semidwarf category. 



It is particularly interest- 

 ing to compare the M.9 clones. 

 Six are included in this trial, 

 and they produce different 

 sized trees. Trees on M.9 

 Pajam 2 had nearly twice the 

 trunk cross-sectional area of 

 trees on M.9 Fleuren 56 after 

 seven seasons. The following 

 M.9 clones are ordered from 

 largest trees to smallest: M.9 

 Pajam 2 > M.9 RN29 > M.9 

 Pajam 1 > M.9 EMLA > M.9 

 NAKBT337 > M.9 Fleuren 56. 

 This range of tree sizes sug- 

 gests that growers planting 

 trees on M.9 rootstock must be 

 careful to know which clone 

 they are purchasing and plan 

 spacing of the trees accord- 

 ingly. 



2 2£ 3 3.6 



Yield efficiency 



Figure 2. Yield efficiency (kg/cm^ trunk cross-sectional area) of Gala trees on 

 several rootstocks in the Massachusetts planting of the 1994 NC-140 Apple Root- 

 stock Trial. 



Fruit Notes, Volume 65, 2000 



