Pawpaw (Asimina triloba), also known as Indiana banana, hoosier banana, and poor man’s banana, is the only temperate member of the tropical Annonaceae family (custard apple family) and is the largest edible tree fruit native to the United States.
Pawpaws grow in the deep, rich fertile soils of river-bottom lands where they grow as understory trees or thicket-shrubs. They grow in 25 states in the eastern United States ranging from northern Florida to southern Ontario (Canada) and as far west as eastern Nebraska and are hardy in Zones 5-8. In South Carolina, it is best to avoid coastal climates due to the tree’s susceptibility to humidity and the need for chill days. It is a slow growing tree that requires several years of growth before it will produce fruit.
Pawpaws are ideally suited for the residential ‘edible’ landscape due to their lush, tropical appearance, attractive growth form, size, fall color and delicious fruit. In addition, Asimina spp. are suitable for butterfly gardens as they attract the zebra swallowtail (Eurytides marcellus) for whom they are the exclusive larval host plant.
Pawpaw is a small, deciduous tree that may attain 15 to 30 feet in height. In the forest understory, trees often exist in clumps or thickets. This may result from root suckering or seedlings developing from fruits that dropped to the ground from an original seedling tree. In sunny locations, trees typically assume a pyramidal habit, straight trunk and long, lush, dark green drooping leaves that turn gold and brown in color during the fall.
They require full sun for adequate fruit production, and soil that is well drained, deep, fertile, and slightly acidic (pH 5.5-7). It is essential that seedlings receive adequate water in the year of establishment.
Flowers emerge before leaves in mid spring. The blossoms occur exclusively on previous year’s wood and may reach up to 2 inches in diameter. Flowers are self-incompatible and require cross-pollination. One cultivar, Sunflower, has been reported to be self-pollinating, but it has not been proven. Pollination may be by beetles, which is consistent with the appearance of the flower: dark, maroon-colored petals and an unpleasant aroma. Due to this type of pollination fruit set in the wild is usually low, but under cultivation tremendous fruit loads have been observed and, although it requires some extra labor, hand pollination can be worth the effort.
Pawpaw is an excellent food source. It exceeds apple, peach and grape in most vitamins, minerals, amino acids, and food energy value. Pawpaw fruits are best eaten fresh when fully ripe. The intense tropical flavor and aroma may also be useful for developing processed food products (blended fruit drinks, baby food, ice creams, etc.). The flesh purees easily and freezes nicely. Pawpaw easily substitutes in equal part for banana in most recipes.
Fruits are oblong to cylindrical berries that are typically 1 to 6 inches long, 1 to 4 inches wide and weigh from 7 to 14 ounces. The fruit of some cultivars may weigh close to 3 pounds. They may be borne singly or in clusters that resemble the “hands” of a banana plant (Musa spp.). It has a thin green skin and yellowish flesh. This highly aromatic fruit has a ripe taste that resembles a creamy mixture of banana, mango and pineapple. Ripe fruit turns yellowish-black resembling an over-ripe banana in look, texture and somewhat in flavor. The flesh is rich and sweet with a custard consistency.
Shelf-life of a tree-ripened fruit stored at room temperature is 3 to 5 days. With refrigeration, fruit can be held up to 3 weeks while maintaining good eating quality. Pawpaw is typically eaten in-hand as a fresh fruit or processed into desserts. Within the fruit, there are two rows of large, brown, bean shaped, laterally compressed seeds that may be up to 1 inch long. Seeds contain alkaloids in the endosperm that are emetic, so seeds should not be consumed.
Pawpaw is not yet a commercially important crop in the U.S. due to the perishable nature of the fruit, but they have tremendous potential. Fruit must be frozen to be preserved for any long period of time, and the fruit is so fragile that it is nearly impossible to ship fresh.
Trees can be planted in fall or spring. Ideally, a dormant tree is planted in early spring.
Trees less than 1½ feet tall should be shaded the first year with tree guards or tree shelters because the young shoot is extremely sensitive to sunlight. Pawpaw trees establish and grow best when they are given shelter the first year in the landscape.
Weed control is necessary, especially in the establishment year. Fertilizer application can be accomplished by broadcasting granular fertilizer in the spring. Remove suckers from the plant to select for a single stem tree or allow them to grow into a hedge or screen.
Table 1. Pawpaw Cultivars for South Carolina.
|Allegheny™||Smaller fruit; early ripening & sweet flavor; very productive; may need thinning for larger fruit|
|Davis||Medium size fruit; green skin & yellow flesh; large seeds; keeps well in cold storage|
|Mango||Vigorous growth; orange-yellow flesh; ripens mid – late season|
|NC-1||Hybrid with large fruit & few seeds; excellent flavor with less of a bitter aftertaste than most; thin yellow skin & yellow flesh; few seeds; early ripening|
|Overleese||Oval to round; few seeds; fruits are large & have excellent flavor; mid-season ripening|
|PA Golden||Yellow skin & flesh; early ripening; vanilla custard flavor|
|Potomac™||Very large fruit; mid-season ripening; very good yields; Sweet rich flavor & smooth texture; yellow skin & flesh; very good yields|
|Shenandoah™||Fruit has yellow skin & butter colored flesh; few seeds; ripens in September; medium-large fruit size; propagation restrictions|
|Sunflower||Reported to be self-fertile; large fruit with yellow skin & fruit; few seeds; ripens mid – late Sept.|
|Susquehanna™||Very large fruit; mid to late season ripening; very sweet, rich flavor; few seeds|
|Taytwo||Light green skin & yellow flesh; ripens in September; medium fruit size|
|Wabash™||Very large fruit; mid-season ripening; very good yields; overall excellent quality; sweet flavor|
|Wells||Green skin & orange flesh; medium size fruit; ripens mid-season|
There are other cultivars available on the market, both with and without propagation restrictions (trademarked name), but these were the ones recommended for the Southeast, and found to be the most popular with consumers and growers of pawpaw trees.
Transplanting trees from the wild is often unsuccessful because the large taproot is easily damaged. Transplanting trees from the wild is usually unsuccessful. Young trees dug from thickets or groves are often root suckers with only a few, brittle roots that have very few root hairs. Due to the poorly developed root system and frequent absence of shelter following transplanting, transplant shock is usually severe resulting in the death of the root sucker.
Transplanting of seedlings from the wild is most successful when done in the spring during budbreak. If many roots are lost in the digging process, it is desirable to prune the shoot to bring it into balance with the existing root system.
Unlike transplanting seedlings collected from the wild, containerized seedlings will transplant with a high success rate when planted properly.
Stratification: Seeds should be collected from fresh fruit, cleaned of all pulp and immediately given a cold, moist treatment for 90-120 days. Seeds that dry out will not germinate. Trees started from seed usually produce fruit in 5 to 8 years, while grafted trees may bear fruit in 3 to 4 years after planting.
Pawpaws are easily propagated by several grafting and budding techniques, including whip-and-tongue, cleft, bark inlay, and chip budding. Other vegetative propagation techniques such as root cuttings, hardwood and softwood cuttings and T-budding produce poor results, and tissue cultures result in almost no growth at all.
Pawpaw plants produce natural compounds (annonaceous acetogenins) in leaf, bark and twig tissues that possess both high anti-tumor and pesticidal properties. The high level of natural defense compounds in the tree makes it highly resistant to insect/disease infestation (R.N. Peterson, The PawPaw Foundation, personal observation).
Japanese beetles occasionally damage leaves. Pawpaw is the exclusive larval (caterpillar) host plant for the zebra swallowtail, Eurytides marcellus, although the caterpillars rarely cause any extensive or severe damage.
A disease known as flyspeck, caused by the fungus Zygophiala jamaicensis, has been reported on pawpaw. However, the fungus only grows superficially on the surface of the fruit and does not prevent it from being edible.
Birds and mammals such as foxes, opossums, squirrels, and raccoons eat the fruit. Deer do not feed on the leaves, twigs, or fruit.
Adapted in part from Pawpaw by Desmond R. Layne, Purdue University Center for New Crops & Plant Products. http://www.hort.purdue.edu/newcrop/CropFactSheets/pawpaw.html