loam, which is classified as a sandy or gravelly 

 soil with a tendency to drought. 



Tree growth has been relatively good, and 

 Figure 1 depicts the trunk cross-sectional area of 

 trees on the various rootstocks. Trees on M.7 

 EMLA were the largest in the planting, and 

 those on Mark were the smallest. In this trial 

 there seems to be a difference between M.7 

 EMLA and M.7A. This difference has not been 

 reported elsewhere, but here trees on M.7A were 

 significantly smaller than those on M.7 EMLA 

 after six growing seasons. Trees on Mark are 

 small in this planting, probably not much larger 

 than trees on M.9 would be if included in the 

 trial. 



Yield began in the fourth leaf (Figure 2). In 

 1988, trees on Ott.3, M.7 EMLA, and Mark 

 produced the most fruit per tree. In 1989, trees 

 on M.7 EMLA, M.7A, Ott.3, and Mark were the 



most productive. In 1990, trees on Ott.3 and M.7 

 EMLA continued to be the most productive. 

 Trees on Mark produced very few fruit in 1990, 

 partly because of overproduction based on tree 

 size in 1988 and 1989. Trees on Mark appear to 

 have "runted out" to some degree; therefore, 

 corrective measures will have to be taken to 

 rejuvenate them in the next few years. 



Yield efficiency (Figure 3) relates yield per 

 tree to tree size and gives a rough means for 

 comparing potential production per acre. On a 

 cumulative basis for 1988-90, Ott.3 resulted in 

 the most efficient tree in the planting. Trees on 

 Mark were less efficient than those on Ott.3, but 

 were significantly more efficient than trees on 

 M.9/Alnarp 2, M.7 EMLA, M.26 EMLA, M.7A, 

 or OAR 1. Trees on OAR 1 were the least 

 efficient in the planting, producing only a small 

 number of fruit in 1988, 1989, and 1990. 



140 



Yield per tree (lbs) 



120 - 



100 



80 



BO 



40 



20 



Mill 1990 

 EZ3 1989 

 ^B 1988 



vzzzzzz 



M.9/A.2 



Ott.3 



M.7 EMLA M.26 EMLA 



M.7A 



OAR 1 



Mark 



Figure 2. Yield per tree (1988-90) of Summerland Red Mcintosh trees on various rootstocks 

 planted in 1985. Bars with any letter in common are not significantly different at odds of 

 19:1. 



Fruit Notes, Summer, 1991 



