The trees in the Frankfort trial had some disease and pest problems. Pawpaw leaves can exhibit leaf spot, principally a complex of Mycocentrospora asiminae Ellis & Kellerm., Rhopaloconidium asiminae Ellis & Morg., and Phyllosticta asiminae Ellis & Kellerm (4, 17). Some trees in the Frankfort planting exhibited M. asiminae growth on the leaves and fruit. The advanced selection 7-90 exhibited very little leaf and fruit spot and appears to be resistant to this fungal complex. The pawpaw peduncle borer (Talponia plummeriana Busck) is a moth larva that burrows into the fleshy tissues of the flower causing the flower to wither and drop (17). Pawpaw peduncle borer damage was observed in the Frankfort orchards in 2005 and 2006. Japanese beetles (Popillia japonica Newman) damaged young leaves on pawpaw trees in the planting each year, but damage was very limited. The larvae of the leafroller (Choristoneura parallela Robinson) (12) also damaged pawpaw leaves in the orchard. The zebra swallowtail butterfly (Eurytides marcellus), whose larvae feed exclusively on young pawpaw foliage, will damage leaves, but this damage has been negligible at the two sites. Deer will not generally eat the leaves or twigs, but they will eat fruit that has dropped on the ground and male deer will sometimes rub their antlers on younger trees causing significant damage to or killing the tree.
Based on fruit size, yield, and tree availability, the cultivars ‘Potomac’, ‘Susquehanna’, ‘Wabash’, ‘Overleese’, ‘Shenandoah’, ‘NC-1’, and ‘Sunflower’ can be recommended for production in Kentucky. Some additional PPF advanced selections that show promise are 10-35, 9-58, 2-10, 8-20, 5-5, and 1-68. Orchard performance will continue to be examined at each site in terms of pests, yield, year-to-year consistency, tree decline, and fruit quality characteristics in the coming years at the PRVT plantings. Pawpaw trees generally reach full production by their 7th year, therefore trees at both sites are in full production.
68
This research was supported by U.S. Dept. of Agriculture, Cooperative State Research, Education, and Extension Service Agreement no. KYX-10-05-40P with Kentucky State University. The technical assistance of S. Jones, E. Reed, and J. Lowe is also gratefully acknowledged by the authors. We wish to thank G. Brown for his assistance in propagating trees and establishing the planting in Princeton, Ky.