1200 



0) 



1^ 1000 - 



1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 



Figure 1. Projected annual yields per acre of Summerland Red Mcintosh trees on various rootstocks. Projected 

 yields were based on annual per-tree yields and projected tree densities (Tabic 1 ). 



latively (Table 2) and also in most years. Trees on M.9/ 

 A.2, 0.3, M.26 EMLA, and M.7A yielded similarly, and 

 trees on OARl and Mark yielded the least per tree. 



To relate yield to tree size, it commonly is expressed 

 on the basis of trunk cross-sectional area and referred to as 

 yield efficiency. Efficiency was greatest for trees on 0.3 

 and Mark (Table 2). Trees on M.9/A.2 and M.26 EMLA 

 were the next most efficient, followed by trees on M.7 

 EMLA and M.7A. The least efficient trees were on OARl. 



The best estimate of relative yield capabilities may come 

 from a projection of the yield per acre (Table 2, Figure 1 ). 

 This projection is partially subjective since it is based on a 

 projection of tree density per acre, but it gives some basis 

 for comparison that is rooted in a "real-world" measure- 

 ment. By this measurement, the most productive trees cu- 



mulatively were on Mark, 0.3, M.26 EMLA, M.9/A.2. and 

 M.7 EMLA. The least productive were on OARl. 



The effects of rootstock on fruit size varied from year 

 to year (Table 3); however, 0.3, M.26 EMLA, and M.9/ 

 A.2 consistently resulted in fruit in the largest category. 

 OARl, on the other hand, consistently resulted in fruit in 

 the smallest category. M.7 EMLA, M.7A, and Mark were 

 not consistent in their effect on fruit size. 



The effects of rootstock on fruit color also varied from 

 year to year (Table 4); however, Mark resulted consistently 

 in percent red color development in the highest category. 

 M.7A and M.7 EMLA resulted consistently in red color 

 development in the lowest category. Color development of 

 fruit from trees on OARl, M.9/A.2, M.26 EMLA, or 0.3 

 was inconsistent or intermediate. 



Fruit Notes, Winter, 1995 



