Horticulture Research Program Dr. Kirk W. Pomper Kentucky State University 129 Atwood Research Facility Frankfort, Kentucky 40601 hone: 502-597-5942 / FAX: 502-597-6381 email: kirk.pomper@kysu.edu

“Picking up pawpaws, puttin’ ‘em in your pocket,…way down yonder in the pawpaw patch.’” We’ve been singing the song and the praises of the pawpaw at Kentucky State University (KSU) for some time now. There has been a comprehensive pawpaw program at KSU since 1990, initiated by Dr. Brett Callaway, directed toward developing pawpaw as a new commercial tree fruit crop for Kentucky and the southeastern United States. Dr. Desmond Layne lead the pawpaw program from 1994 until 1997, before moving to Clemson University to work with peaches. Dr. Kirk Pomper took over the program in 1998 and it has diversified a little. The Pawpaw Program has been renamed this year as “The Fruit and Nut Development Laboratory” to reflect our current research efforts involving pawpaws, gooseberries, and currants, along with demonstration plantings of American persimmon and table and wine grapes, as potential new fruit crops for small farmers in Kentucky and the southeastern United States. However, our bread and butter, so to speak, is still the pawpaw, representing about 80% of our research efforts.

The pawpaw [Asimina triloba (L.) Dunal] tree produces the largest edible tree fruit native to the United States, reaching over one lb. in size. Pawpaws are hardy to USDA growing zone 5 (-15oF) and grow wild in the hardwood forests of 26 states in the eastern United States, ranging from northern Florida to southern Ontario (Canada) and as far west as eastern Nebraska. In their native setting, pawpaws usually flourish in the deep, rich, fertile soils of river-bottom lands where they grow as understory trees or thicket-shrubs. There are currently more than forty pawpaw cultivars commercially available, either having been selected in the wild or the result of breeding efforts of hobbyists.

The pawpaw flower has a slight fetid odor and flowers are thought to be self-incompatible and require cross-pollination, although some trees may be self-compatible. Flies and beetles are thought to be pollinators of pawpaw flowers. We have noted the presence of many flies and other insects visiting the pawpaw flowers on sunny warm afternoons; we rarely have seen any insects around the flowers on overcast or cool spring days. Dr. David Gordon, an entomologist at KSU, collected insects on a sunny April afternoon and has identified flesh flies, blow flies, and marsh flies that were visiting the pawpaw flowers. We have never placed any meat or road kill, as some have suggested, in our orchards to attract flies, and we have still had excellent fruit set. The large concentration of pawpaw trees at the KSU farm may help attract the many insects we have seen visiting the flowers, hence pollinators are not limiting. In the years to come, we hope to develop recommendations on which cultivars serve as pollinizers for other cultivars. To our knowledge it has never been documented that ‘Sunflower’, often stated to be self-fertile, is really self-compatible. There is much work to be done in the area of pawpaw pollination.