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selections from the wild were assembled in extensive collections by various enthusiasts and scientists, including Benjamin Buckman (Farmington, Illinois, circa 1900 to 1920), George Zimmerman (Linglestown, Pennsylvania, 1918 to 1941), and Orland White (Blandy Experimental Farm, Boyce, Virginia, 1926 to 1955) (16, 17, 18, 24). From about 1900 to 1960, at least 56 clones of pawpaw were selected and named. Fewer than 20 of these cultivars remain, with many being lost from cultivation through neglect, abandonment of collections, and loss of records necessary for identification (17). Since 1960, additional pawpaw cultivars have been selected from the wild or developed as a result of breeding efforts of hobbyists. More than 40 clones are currently available (7). The loss of cultivars over the last century may have led to erosion in the genetic base of current pawpaw cultivars (6). Urban encroachment and the resulting destruction of native pawpaw patches may also be leading to a reduction in genetic diversity in the wild.

In 1981, R. Neal Peterson and Harry Swartz began a long-term breeding project to develop improved pawpaw cultivars (16, 17, 18). A collection of about 1500 accessions of open-pollinated seedlings was assembled at the University of Maryland Experiment Stations at Queenstown and Keedysville, Maryland. The seed for this germplasm collection was obtained from pawpaw trees that remained at the sites of the historic collections of Buckman, Zimmerman, and the Blandy Experimental Farm, as well as those of Hershey (Dowington, Pennsylvania), Allard (Arlington, Virginia), Ray Schlaanstine (West Chester, Pennsylvania), and open-pollinated seed from some modern cultivars.

In 1993, the Pawpaw Foundation (PPF) and Kentucky State University (KSU) embarked on a joint venture to test 10 commercially available pawpaw cultivars and 18 of PPF’s advanced selections from the Maryland orchards in a Pawpaw Regional Variety Trial (PRVT), which was established on the properties of 13 universities or private cooperators (10, 19, 20). The PRVT was established in Princeton, KY in 1995 and the Frankfort, KY planting was established in 1998. The objective of the PRVT plantings was to evaluate commercially available named pawpaw varieties and PPF’s advanced selections within and outside of the pawpaw’s native range. Here we report on the performance of the PRVT in Kentucky for mature trees at the Frankfort and Princeton sites.

(10, 19, 20). The PRVT was established in Princeton, KY in 1995 and the Frankfort, KY planting was established in 1998. The objective of the PRVT plantings was to evaluate commercially available named pawpaw varieties and PPF’s advanced selections within and outside of the pawpaw’s native range. Here we report on the performance of the PRVT in Kentucky for mature trees at the Frankfort and Princeton sites.

The 28 grafted scion varieties (Table 1) were propagated on seedling rootstock produced from open-pollinated half-sibling trees as described by Pomper et al. (20). At both Kentucky PRVT sites, eight replicate trees of each of clone (Table 2) were planted in a randomized complete block design with eight complete blocks (block = 4 rows x 7 trees) at an in-row spacing of 2 m and between-row spacing of 5.5 m. Rows were placed in north-south orientation. During the trial, some advanced selections were named and released; in this case, the cultivar name and advanced selection number are both included in Table 1.

For the Frankfort location trees were planted in late March, 1998. A total of 224 grafted trees (eight trees of each selection) and 75 Kentucky seedlings serving as border row trees were planted in a Lowell silt loam soil (pH 6.9) at the KSU Research and Demonstration Farm in Frankfort, Ky. Trees were fertilized with Peters 20-20-20 (20N-8.7P-16.6K) water-soluble fertilizer (Scotts Co., Marysville, Ohio) once in May, June, July, and August each year for a total of 12.1 kg/ha of nitrogen (N). Corrective pruning was implemented in late spring by removing only the lower limbs below a height of about one meter. Additional irrigation was provided as needed by drip irrigation; each tree had two emitters per tree (5.7 liters/hour each).

For the Princeton planting, 224 grafted trees (eight trees of each selection) and 75 Kentucky seedling trees as border row trees were planted in Oct. 1995, in a Crider silt loam