Enhancing Pawpaw Chip Budding Success

1 Principal Investigator of Horticulture and Curator, USDA Naitonal Clonal Germplasm Repository for Asimina species, Atwood Research Facility, Kentucky State University, Frankfort, KY 40601-2355. To whom reprint requests should be addressed. 2 Co-Investigator of Horticulture, Atwood Research Facility, Kentucky State University, Frankfort, KY 40601-2355 Abstract The pawpaw [Asimina triloba (L.) Dunal] is gaining popularity as a commercial tree fruit. Pawpaw cultivars are usually propagated by chip budding. The objectives of this study were to determine 1) if leaving 6 to 8 leaves on pawpaw rootstock upon chip budding improved budding success and scion growth in greenhouse-grown container production and 2) if genetic background of the seedling rootstock or scion affected chip budding success or scion growth. An experiment was conducted using a three-way factorial design with six replicate blocks, with treatments of two scions (‘Sunflower’ and ‘Susquehanna’), two seedling rootstocks (Sunflower and K8-2), and two leaf treatments (removing leaves vs. leaving 6-8 leaves at budding). Trees were chip-budded in late June 2006. Retaining leaves on the rootstock seedling increased scion bud break (76%) on rootstocks compared to budding onto rootstocks with all leaves removed (54%). Removal of the remaining rootstock leaves after 6 weeks had an additional positive effect. After leaf removal at 6 weeks, an additional 11% of buds broke on rootstocks that had previously retained their leaves. Only 1% more buds broke after the 6 week point on rootstocks that had leaves removed from the beginning. The K8-2 seedling rootstock had a higher budding success (80%) than Sunflower seedling rootstock (62%). Although cutting back the rootstock and removing competing leaves at the time of chip budding would be more convenient and require less labor for nurseries, this practice cannot be recommended due to the reduced chip budding success (55% vs. 87%).