Ian A. Merwin,1 Rachel Byard,2 and Kirk W. Pomper3
ADDITIONAL INDEX WORDS. Asimina triloba, tree-tubes, pollination
SUMMARY. A pawpaw regional variety trial (PRVT) was established at Cornell University, Ithaca, N.Y. in Apr. 1999 consisting of 28 commercially available pawpaw (Asimina triloba) varieties or advanced selections from the PawPaw Foundation (PPF; Frankfort, Ky.). Eight replicate trees of each selection, grafted onto seedling rootstocks, were planted in a randomized block design. The first two winters at the test planting site were unusually mild for the Finger Lakes region, with the lowest recorded temperatures above -16 circ C (3.2 circ F). Despite these mild winters, there was extensive winter mortality of some pawpaw varieties. Survival rates were > 75% for 11 varieties, and were < 40% for five other varieties. Poor establishment of grafted clonal pawpaws and insufficient pollination or fertilization of established pawpaws were important limitations of successful commercialization of this new fruit crop under conditions typical of upstate New York. Open mesh black plastic trunk guards provided adequate shade and protection for newly planted pawpaws, whereas translucent plastic tree-tubes caused heat stress and scorching of the young trees.
The Finger Lakes and Lake Ontario regions of upstate New York are at the northern limits of the original range for pawpaw in North America (Darrow 1975; Kral 1960). When the national PRVT was organized in 1994, we offered to establish a test planting on a Cornell research farm in Lansing, N.Y., to evaluate survival and adaptation of promising pawpaw varieties in a cool humid fruit-growing region (Layne, 1996; Pomper et al., 1999).
In April 1999, we received and planted 224 recently grafted pawpaws from the PRVT nursery in Oregon, representing eight replications of 28 varieties. This planting included 10 commercially available varieties and 18 advanced selections from PPF grafted onto seedling rootstocks. Named varieties in the trial included: Middletown (selected in Ohio), Mitchell (Illinois), NC-1 (Ontario, Canada), Overleese (Indiana), PA-Golden #1 (New York), Sunflower (Kansas), Taylor (Michigan), Taytwo (Michigan), Wells (Indiana), and Wilson (Kentucky). The other 18 clones that we evaluated were selected from PPF orchards by R. Neal Peterson at the University of Maryland Experiment Stations at Queenstown and Keedysville, Md.
The PPF advanced selections were selected based on superior traits including fruit size and taste, high flesh-to-seed ratio, resistance to pests and diseases, and overall productivity on a year-to-year basis.
1Associate professor, 118 Plant Science Bldg. Dept. of Horticulture, Cornell University, Ithaca, NY 14853-5908.
2Research assistant, 118 Plant Science Bldg. Dept. of Horticulture, Cornell University, Ithaca, NY 14853-5908.3Principal investigator of horticulture and curator, USDA National Clonal Germplasm Repository for Asimina species., Atwood Research Facility, Kentucky State University, Frankfort, KY 400601-2355.
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