depicts the relative canopy dimensions of these 

 trees. M.7 EMLA produced the largest trees. 

 Trees on M.26 EMLA and OARl were the next 

 smaller in terms of trunk cross-sectional area, 

 followed by trees on 0.3 and MAC. 9. Trees on 

 M.9 EMLA were smaller still, and the smallest 

 trees in the planting were on M.9 and M.27 

 EMLA. Clearly, M.9 and M.27 EMLA were not 

 vigorous enough rootstocks for Starkspur Su- 

 preme Delicious, since trees did not reach six 

 feet in height. With a canopy this smgdl, ad- 

 equate yields are not possible. 



Figure 2 plots the trunk cross-sectional area 

 of these trees from 1980 through 1993, and 

 shows that for most trees, there was a relatively 

 constant rate of growth throughout the experi- 

 ment. MAC. 9, however, resulted in a relatively 



fast growth rate for the first five growing sea- 

 sons, but for the next nine seasons, had a signifi- 

 cantly slower growth rate. In other words, the 

 initial growth rate of trees on MAC. 9 was nearly 

 as great as that of trees on M.7 EMLA, but later 

 on, the growth rate was only similar to that of 

 trees on M.9 EMLA. This reduction in growth 

 rate corresponded to the onset of heavy produc- 

 tion from trees on MAC. 9. 



Table 1 also gives estimates of spacing and 

 density for these combinations. For most com- 

 binations, the estimated in-row spacing is ap- 

 proximately ninety percent of the tree spread; 

 however, this assessment was not adequate for 

 trees that had filled their allotted space and had 

 required containment pruning. Specifically, 

 the estimated spacing of trees on M.7 EMLA 



fruit Notes, Spring, 1994 



