Based on the number of poster presentations and sessions covering pawpaw at this year’s American Society for Horticultural Science (ASHS) conference, it appears the fruit tree is continuing to grow in popularity among both researchers and growers.

It was great timing to build enthusiasm – the fifth International Pawpaw Conference is coming to Frankfort, KY, Sept. 9 – 11. The conference is sponsored by the Kentucky State University Land Grant Program, the North American Pawpaw Growers Association and the Ohio Pawpaw Festival (slated for Sept. 12 – 14). Themed “Cultivating Excellence: The Next Chapter in Pawpaw Development,” the Kentucky conference will feature discussions on emerging and historical pawpaw cultivars, innovative breeding approaches and the development of a comprehensive pawpaw registry.

Much of the information shared at the ASHS conference included Dr. Kirk Pomper, professor of horticulture and pawpaw devotee; Sheri Crabtree, MSc, horticulture research and Extension associate; Jeremy Lowe, MS, horticulture research associate; all heavily involved in the Pawpaw Program at Kentucky State University.

For those interested in improving their pawpaws (or curious about adding them to their existing operations), the research discussed can be incredibly useful.

Six Advanced Selections to Study

The Pawpaw Program at KYSU is robust, and one of the most important things it does is test cultivars.

The pawpaw is a temperate fruit species in the custard apple family (Annonaceae family) and the northernmost growing “tropical” fruit tree. It grows small to medium height trees with unique and flavorful fruit (often described as like a banana or mango). It can provide a new crop for small farmers and for those interested in creating value-added products, such as ice cream, jams, wine and beer.

In the wild, the fruit tend to be fairly small, so breeders are continuously working toward regularly growing fruit that measure 120 grams or larger, as they are considered large enough for commercial sale.

In addition to Lowe, Crabtree and Pomper, Kirie Broberg (greenhouse manager for the College of Agriculture, Health & Natural Resources at KYSU) and Page Barker looked at the fruit weights, percent seed and soluble solids content of six advanced selections from KYSU’s Pawpaw Breeding Program.

The program has currently released three different cultivars: ‘KSU-Atwood,’ ‘KSU-Benson’ and ‘KSU-Chappell.’ This study compared selections named ‘Hi 1-4,’ ‘Hi 7-1,’ ‘G4-25,’ ‘G6-120,’ ‘G9-109’ and ‘G9-111’ to Atwood and Chappell as well as another cultivar, ‘Ralph’s Whopper.’

More high yielding cultivars with excellent fruit quality would help grow the burgeoning pawpaw industry.

During the experiment, ripe fruit were harvested thrice weekly. Fifteen fruits were chosen at random from each cultivar and their fruit weight, percent seed by weight and soluble solids content were measured. Pawpaw fruit tend to have large seeds, so cultivars that had smaller or fewer seeds would be favorable.

Some of the results showed promise: Hi 1-4 had the largest average fruit size (229 g), followed by Chappell (197 g). On the other hand, G4-25, G9-109, G9-111 and Ralph’s Whopper produced the smallest fruit.

Chappell had the lowest average percent seed (4.7%). Hi 1-4, G9-109 and Ralph’s Whopper were the next lowest, at 6.3% seed or less. Hi 7-1, however, had the highest seed content at 9.3% seed by weight.

Looking at soluble solids, Hi 1-4 and G9-109 had the highest amount, at over 24 Brix (a measurement of the dissolved solids, often sugars, in a solution). G9-111 had the lowest (at 21 Brix).

Based on these results, the researchers believe cultivars Hi 1-4 and Hi 7-1 showed excellent fruit size and the potential to be new commercial cultivars. Additional characteristics, like their ease of propagation, tree yield, flavor and other characteristics, will continue to be evaluated over the next several years.

To continue this work, Hi 1-4 and Hi 7-1 have been budded onto seedling rootstock for further evaluation.

The popularity of pawpaw continues to grow, especially in the Bluegrass State, where the Kentucky State University Pawpaw Program is headquartered. Photo courtesy of T. Davis Sydnor, Ohio State, Bugwood.org

Digging Deeper into Hi 1-4 & Hi 7-1

Crabtree, Lowe and Pomper kept things rolling by presenting some yield data on these two particular cultivars with a poster presentation.

They noted the North American pawpaw is currently being produced on a small scale commercially across the U.S. and internationally – and there are over 90 pawpaw growers in Kentucky alone.

While there are approximately 50 cultivars available to growers, some of them tend to be of poor quality, are low yielding, produce small fruit size and/or exhibit poor flavors. KYSU’s Pawpaw Program is striving to develop cultivars with both good flavor and high yields.

This study compared the fruit yield from Hi 1-4 and Hi 7-1 to the commercially available cultivars ‘KSU-Benson’ and KSU-Chappell. The variety trials have been taking place at KYSU’s Harold R. Benson Research & Demonstration Farm in Frankfort, KY, since 2017. Data on the number of fruits, fruit clusters per tree and fruit weights were collected to compare the Hi cultivars to the established KYSU ones.

In 2024, Hi 1-4 and Hi 7-1 had large average fruit weights of 213 g and 167 g, respectively. Benson (179 g) and Chappell (234 g) also had large, marketable fruit.

However, yield per tree was lower in the new cultivars last summer. Hi 1-4 produced just 12.8 kg/tree and Hi 7-1, 12 kg. Comparatively, Benson averaged 16.9 kg/tree and Chappell, 27.2 kg.

As it is desirable for pawpaws to have fewer fruit/cluster and more single fruit, for ease of harvesting, lower numbers in this category are preferred. Hi 1-4 and Benson averaged under two fruit/cluster while Hi 7-1 and Chappell averaged slightly more than two fruit/cluster.

The research team reported that since Hi 1-4 and Hi 7-1 have large, flavorful fruit and high yields, there are plans to name them and release them officially as new cultivars from the KYSU pawpaw breeding program at the International Pawpaw Conference.

A Hopeful Cultivar Option: HAWK238

As previously noted, pawpaw fruit has both fresh market appeal for farmers markets, CSAs and organic markets as well as processing potential for frozen pulp production and other value-added goods.

The cultivar ‘HAWK238’ had been identified by a private grower as having a unique fruit type and boasting promising characteristics as a potential new option. To see how it measured up, in 2024, the fruit size and quality of the well-established pawpaw cultivars ‘Susquehanna’ and ‘Shenandoah’ were compared to HAWK238.

The pawpaw trio of Pomper, Lowe and Crabtree also shared this experiment’s results. The trees were located at the private grower’s location in Franklin County, KY (USDA Hardiness Zone 7A). The fruit characteristics for 20 fruits from each selection were evaluated for fruit weight and Brix.

The fruit size was similar in Susquehanna, Shenandoah and HAWK238, averaging 190 g, 155 g and 154 g, respectively. The Brix of ripe fruit was significantly lower in Shenandoah (17.7 Brix) compared to Susquehanna (25.4 Brix) and HAWK238 (24.3 Brix).

Additionally, it was noted HAWK238 had “a pleasing orange flesh with a mild banana-mango flavor.” Because of these positive characteristics, the pawpaw program team said HAWK238 will be included in additional cultivar trials.

Want to learn more about all the work being done in the KYSU Pawpaw Program? Head to kysu.edu/academics/college-ahnr/school-of-anr/pawpaw.

by Courtney Llewellyn