Pioneer Mac, the Mcintosh Strain 

 of the Future? 



Wesley R. Autio 



Department of Plant & Soil Sciences, University of Massachusetts 



Pioneer Mac, technically, is not a Mcintosh 

 strain. It, however, is an open- 

 pollinated seedling of Mcintosh. It was found by 

 Ernest Greiner (Pioneer Fruit Farms) in Marlboro, 

 NY in 1976. Since that time, Adams County Nurs- 

 ery, Inc. has propagated it commercially. Even 

 though it is not a strain but is a new cultivar, I will 

 refer to it as a strain, since it is virtually indistin- 

 guishable from Mcintosh. 



Is Pioneer Mac the strain of the future? Early 

 observations from New York suggested that Pioneer 

 ripened later and dropped fewer fruit than stan- 

 dard Mcintosh strains. When it was first released 

 in 1988-89 those were very desirable characteris- 

 tics, since we were in the midst of the Alar contro- 

 versy. In 1988, we established a trial with the goal 

 of characterizing the tree productivity, fruit ripen- 

 ing, fruit quality, and fruit drop of Pioneer Mac trees 

 in comparison with standard Mcintosh strains. 



A trial was planted in the spring of 1988 at the 

 University of Massachusetts Horticultural Research 

 Center in Belchertown that included ten replica- 

 tions of Pioneer Mac, Rogers Red Mcintosh, and 

 Marshall Mcintosh all on M.26 EMLA. Tree size 

 (trunk cross-sectional area) and total yield were 

 measured throughout the experiment. Fruit size 

 was measured from 1992 through 1995, and red 



color was assessed in 1992 and 1993. Ripening was 

 tracked with internal ethylene levels from 1990 

 through 1993, and natural drop was followed in 1994 

 and 1995. 



Pioneer Mac trees were larger than Marshall 

 trees, but were not different from Rogers trees (Table 

 1). Yield followed the same pattern (Table 1), but 

 yield efficiencies of the three strains were similar 

 (Table 1). That is, differences in yield were the re- 

 sult of somewhat different tree vigors and likely 

 would not result in actual differences in yield per 

 acre. Crop loads (fruit number per unit of tree size) 

 were similar among the three strains for the four 

 seasons from 1992 through 1995 (Table 1). Rogers 

 produced the largest fruit over the same four-year 

 period (Table 1). Color was affected significantly 

 by strain (Table 1). Marshall fruit colored over a 

 greater percent of the fruit surface than did the 

 other strains, as would be expected. Pioneer fruit 

 colored slightly (but statistically significantly) more 

 than Rogers fruit. It is uncertain whether or not 

 the difference between Pioneer and Rogers is prac- 

 tically significant. 



Ripening means represent relative ripening 

 date, that is the date when the average internal 

 ethylene concentration of fruit reached one ppm 

 (Table 1). Marshall fruit ripened on average three 



Table 1. The effects of Mcintosh strain on tree size, yield, jdeld efficiency, crop load, fruit size, and 

 fruit color 



Strain 



Trunk 

 cross- 

 sectional 

 area, 1995 



(in^) 



Cumulative 



yield 



1990-95 



(bu) 



Cumulative 



yield 



efficiency 



1990-95 



(bu/in^ TCA) 



Crop load 

 1992-95 



(no/in^ 

 TCA) 



Fruit size 

 1992-95 

 (no./bu) 



Red 



color 

 1992-93 



(%) 



Averate 

 ripening 



date 

 (1990-93) 



*Means within columns not followed by the same letter are significantly different at odds of 19 to 1. 



Fruit Notes, Winter, 1996 



