Establishment, Productivity, Cross-Compatibility and Pollen Vectors for 28 Pawpaw Cultivars In Upstate New York

A pawpaw (Asimina triloba) variety trial was established near Ithaca, N.Y. in April 1999, consisting of 28 advanced selections and cultivars from the USDA PawPaw Germplasm Repository in Kentucky. Eight replicate trees of each genotype were obtained as dormant bench-grafts on seedling rootstocks, and planted in a randomized block design at a site near Cayuga Lake.  Survival during the first two years ranged from 100% (for Taytwo, 2-54, and NC-1) to 12.5% (for 3-21), and heat stress during the first summer was the primary cause of mortality.  Dead trees were replaced in 2000, and after 10 years tree survival ranged from 100% (for Taytwo and NC1) to 25% (for 3-21 and 4-2).  Cumulative tree size (TCSA at 30 cm above graft unions) after 10 years ranged from 128.2 cm2 for NC-1, to 44.5 cm2 for 1-7-2.  Cumulative yields per tree ranged from 67.2 kg per tree for 1-7-1, to 3 kg per tree for 3-21.  Average fruit fresh weights ranged from 231 g for 1-7-1, to 74 g for Wilson.  All of the surviving trees remained healthy during ten years of observations, and did not exhibit the leaf blight reported for other pawpaw plantings, although cultivars 9-47, 1-68 and 5-5 did show mild leaf spot symptoms during some years. Most cultivars began flowering and bearing in the fifth year after planting.  Biennial bearing was evident in most cultivars, with 1-7-1, 2-10, PA-Golden and Taytwo being the most annually productive. The average ripening dates ranged from day-of-year 264 (for 3-21) to day 291 (for 2-54). We monitored pollinator activity throughout bloom in 2006, and observed aggregations of Nitidulidae beetles around the stamens, and occasional floral visits by Lampyridae beetles, but no visits by carrion flies or beetles.  Pollen anthesis preceded or followed apparent stigma receptivity in most cultivars, but controlled cross-pollination tests indicated that all 28 of the varieties were at least partially self-compatible. Consumer acceptance of all 28 cultivars was generally positive in a local retail market; fruit that were harvested when they began to soften and ground color had changed from pale green to pale yellow maintained acceptable condition for about six weeks in regular air storage at 2 degrees C.