The Influence of Rootstock and Training System on Performance of Two North American Pawpaw Cultivars

Abstract

The pawpaw [ Asimina triloba(L.) Dunal] is the largest tree fruit indigenous to the United States and is commercially produced on a small scale as a niche fruit crop. Pawpaws are not currently commercially propagated via cuttings, layering, or tissue culture, and clonal rootstocks are not available for pawpaw cultivars. A study was conducted to determine if establishment survival, vigor, scion precocity, and fruit yield vary by pawpaw cultivar (‘Susquehanna’ or ‘Sunflower’), seedling rootstock source [seedlings of Sunflower, PA-Golden, Susquehanna, KSU-Atwood, and mixed seed collected from the pawpaw regional variety trial (RVT)], and pruning method (either minimal pruning or central leader training). By the sixth year of the study, there was a significant difference in survival by cultivar, ‘Susquehanna’ (46%) and ‘Sunflower’ (68%). Trees on Susquehanna and KSU-Atwood seedling rootstock had survival percentages below 60% and therefore are not recommended for use as a rootstock source. Rootstock did not significantly influence trunk cross sectional area, precocity, number of flowers, or yield. Trees with a ‘Susquehanna’ scion had greater fruit weight than those with a ‘Sunflower’ scion. Training method had a great impact, with minimally-pruned trees having greater yields per tree than central leader trained trees. However, central leader-trained trees had greater fruit weight than in minimally-pruned trees, which is desirable. Central leader trained trees were initially dwarfed, but displayed a stronger tree architecture with less breakage and facilitated orchard care of trees and weed control.