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Pawpaw

Pawpaw (Asimina triloba), also known as papaw, Indiana banana, Hoosier banana, Michigan 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 shrubby thickets. 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 USDA Zones 5 to 8. In South Carolina, it is best to avoid coastal climates for most varieties due to the tree’s need for winter chilling though some selections from its southern range likely only require 400-600 chill hours. Pawpaw is a slow-growing tree that requires 3 to 4 years of growth before it has the physical structure to produce and support the fruit clusters.

Pawpaws are ideally suited for the residential “edible” landscape due to their lush, tropical appearance, attractive pyramidal growth form, small tree size, vibrant yellow fall color, few insect or disease pests, and fruit that possesses hints of subtropical flavors. In addition, pawpaws are suitable for butterfly gardens as they are the exclusive larval host plant of zebra swallowtails (Eurytides marcellus).

Description

Pawpaw is a small, deciduous tree that may attain 15 to 30 feet in height. It can often be found in the forest understory, where it grows in clumps or thickets. This usually results from prolific root suckering, although seedlings may develop from fruits that drop to the ground but are uncommon and often are found some distance from a pawpaw thicket as the fruit is carried off and consumed by animals. In sunny locations, trees typically form a pyramidal shape with a single straight trunk bearing 6 to 12 inch, obovate-oblong, dark green, drooping leaves that turn yellow in the fall.

Flowers emerge before the leaves in mid-spring, with the flowering period often extending over several weeks. The blossoms exclusively occur on the previous year’s branches and may be up to 2 inches wide. Flowers are self-incompatible, which means that flowers must be cross-pollinated. Thus, pollen from an unrelated, genetically different pawpaw is necessary for fertilization and fruit set to occur.

Pollination is thought to be done by nitidulid beetles (night flying) or bottle flies (day foragers), which is consistent with the appearance of the flower that has dark, maroon-colored petals and a weak, unpleasant aroma. Fruit set is usually low in the wild due to a scarcity of pollinators. Under cultivation, some trees can produce up to 25 to 50 pounds per tree. If pollinators are scarce, hand pollination, although laborious, can be worthwhile.

Pawpaw flowers (Asimina triloba) have dark, maroon-colored petals.

Pawpaw flowers (Asimina triloba) have dark, maroon-colored petals.
R. F. Polomski, ©2022, Clemson University

Inch-long, "hand" clusters of fruit develop after successful pollination.

Inch-long, “hand” clusters of fruit develop after successful pollination.
David Ouellette, ©2022, Clemson University

Fruit

Taxonomically, fruits are oblong to cylindrical berries. They are typically 1 to 6 inches long, 1 to 4 inches wide, and weigh from 7 ounces to as much as 2 pounds. Borne singly or in clusters, the fruits resemble the “hands” of bananas (Musa spp.). Some pawpaw clusters can weigh up to 3 pounds.

Pawpaw (Asimina triloba) fruit may be borne singly or in clusters.

Pawpaw (Asimina triloba) fruit may be borne singly or in clusters.
David Ouellette, ©2022, Clemson University

Pawpaws have a thin green skin and yellow, golden, or white flesh. This highly aromatic fruit tastes similar to a banana, mango, or pineapple. The fruit should not be harvested until the skin gives (indents) slightly with a finger squeeze as fruit do not ripen properly if picked when very firm. The skin of ripening fruit turns light green to yellowish (peak ripeness) to black (over-ripe), which mimics the stages of a ripening banana in look, texture, and somewhat in flavor. The flesh is rich and sweet with a custard-like consistency and is best eaten with a spoon. Seeds are large, smooth, and easily discarded when eating.

The shelf-life of a tree-ripened fruit stored at room temperature is 3 to 5 days. With refrigeration, fruit can last up to 3 weeks while maintaining good eating quality. Pawpaw is typically eaten as fresh fruit or processed into desserts. Inside the fruit are two rows of large, brown, bean-shaped seeds that may be up to 1 inch long. Seeds and the green peel (skin) contain alkaloids that are emetic (which causes vomiting); therefore, the seeds and peel should not be consumed.

Pawpaw is an excellent food source that is high in carbohydrates. It exceeds apple, peach, and grape in most vitamins, minerals, amino acids, and food energy values. For the best flavor, eat fully ripe pawpaw fruits. Its intense tropical flavor and aroma are ideal for processed food products, including blended fruit drinks, baby food, ice creams, etc. The flesh purees easily and freezes nicely. Pawpaw can be a substitute for equal parts of banana in most recipes. Pawpaw also makes a flavorful fruit wine.

Pawpaw is not a commercially important crop in the U.S. due to the highly perishable nature of the fruit. However, it does have economic potential for roadside markets, high-end restaurants, and processed products. Freeze the pulp to preserve it for an extended period. Careful handling and overnight delivery are necessary for it to be sold fresh at markets.

Cultivars

Table 1. Pawpaw cultivars suited for South Carolina.

Cultivar1 Description2
Allegheny® Smaller fruit; early ripening & sweet flavor; very productive; may need thinning for larger fruit
KSU-Atwood™ Greenish-blue skin with yellow-orange flesh; fruit size and flavor medium but very productive
KSU-Benson™ Round, medium-sized, early ripening, orange flesh with few seeds; rich, tropical-flavored fruit; very productive tree
KSU-Chappell™ Extra-large, sweet, mild banana-pineapple flavored fruit; very vigorous tree
Davis Medium size fruit; green skin & yellow flesh; smaller flesh to seed ratio (i.e., seedy); keeps well in cold storage
Duckworth #1 & #2 Cultivars that originated in Florida and are best adapted to the Coastal Plain
Mango Vigorous growth; orange-yellow flesh; originated in southern Georgia
NC-1 Large fruit of excellent flavor with less of a bitter aftertaste than most; thin yellow skin & yellow flesh; few seeds
Overleese Oval to round; high flesh to seed ratio; fruits are large & have excellent flavor; mid-season ripening
PA Golden Yellow skin & flesh; early ripening; vanilla custard flavor
Potomac® Very large fruit; very good yields; sweet, rich flavor & smooth texture; yellow skin & flesh
Shenandoah® Fruit has yellow skin & butter-colored flesh; high flesh to seed ratio; medium-large fruit size
Sunflower Large fruit with yellow skin & fruit; high flesh to seed ratio; originated in eastern Kansas, has good winter hardiness but can emerge from dormancy too early in response to warming temperatures in late winter and risk injury.
Susquehanna® Very large fruit; very sweet, rich flavor; high flesh to seed ratio
Taytwo Light green skin & yellow flesh; medium fruit size
Wabash® Very large fruit; very good yields; overall excellent quality; sweet flavor
More cultivars are commercially available than those listed in this table. Cultivars not in Table 1 have not been extensively tested for their suitability in the Southeast or have limited availability.

2 While the descriptions of fruiting characteristics are often based on a few primary locations, such as Kentucky and Maryland, fruit size, flavor and flesh color among cultivars are consistent across states.

Wabash pawpaw fruit. One of the largest fruited cultivars.

Wabash pawpaw fruit. One of the largest fruited cultivars.
Gregory Reighard, ©2022, Clemson University

Cultivation

Although an understory tree in its native habitat, pawpaw trees require full sun for the best fruit production. Soil that is well-drained, deep, fertile, and slightly acidic (pH 5.5 to 7.0) is ideal, but trees will grow fine on most soils that contain adequate levels of calcium as determined by a soil test and if mulched.

Plant trees in the fall or spring, preferably as a dormant tree in early spring. Digging out and transplanting trees from the wild is often unsuccessful because their large taproot is easily damaged. Young trees dug from thickets or groves of pawpaws are often just root suckers with a few fine, brittle roots. Often these “root sucker” trees fail to establish and die due to a poorly developed root system and the absence of a protective shelter that provides partial shade to reduce water loss from the leaves via transpiration.

Pawpaw (Asimina triloba) container-grown seedlings will transplant with a higher success rate.

Pawpaw (Asimina triloba) container-grown seedlings will transplant with a higher success rate.
S. Cory Tanner, ©2015, Clemson University

Wild seedlings have a better chance of survival when transplanted in the spring before budbreak. If the seedling is large (i.e., more than 2 to 3 feet tall) and if many of the roots are damaged in the digging process, prune back some lateral branches (keep the terminal or topmost shoot) to compensate for the loss of roots. Transplanted wild trees will almost always produce fruit inferior to named cultivars. Plant grafted cultivars if fruit production and quality are the primary goals.

Container-grown, grafted cultivars are strongly recommended as they will transplant more successfully than bare-root seedlings collected from the wild and produce superior fruit.

Mature pawpaw trees will sucker profusely from the roots.

Mature pawpaw trees will sucker profusely from the roots.
Gregory Reighard, ©2022, Clemson University

Trees less than 3 feet tall should be shaded the first year with tree guards or tree shelters because the young shoots are sensitive to full sunlight. Pawpaw trees establish and grow best when given shelter or partial shade for the first year or two in the landscape. Once established, pawpaws eventually produce root suckers around the trunk of the tree. Remove root suckers to maintain a single-trunk tree for faster growth and earlier fruiting.

Weed control weed is necessary, especially during the establishment period, which may be as long as a year or more. Unless planted on infertile soil or sand, providing water when needed will be sufficient until trees begin to grow. Once the trees are established, an annual spring broadcast of a balanced granular fertilizer, such as 10-10-10, from the trunk to the outermost branches is often adequate though increasing soil organic matter at planting can be beneficial for encouraging arbuscular mycorrhiza associations on pawpaw roots for improved nutrient uptake. When the pawpaws begin bearing fruit, calcium may need to be applied depending on the soil pH and fertility as determined by a soil test. For more information on soil testing, see HGIC 1652, Soil Testing.

Mulching is very beneficial for maintaining soil moisture in the root zone area and reducing weed growth. Moreover, a straw mulch helps to cushion ripe fruit when they drop from the tree in cases when the trees cannot be harvested every day. For more information on mulching, see HGIC 1604, Mulch.

Pawpaw fruit drop soon after ripening. Straw mulch under the trees reduces bruising. Note the pyramidal form of the mature tree.

Pawpaw fruit drop soon after ripening. Straw mulch under the trees reduces bruising. Note the pyramidal form of the mature tree.
David Ouellette, ©2022, Clemson University

After harvest, pawpaw trees, such as 'Wells', add attractive fall color in the landscape.

After harvest, pawpaw trees, such as ‘Wells’, add attractive fall color in the landscape.
R. F. Polomski, ©2022, Clemson University

Propagation

Seed Stratification: Collect seeds from fresh fruit, remove all the pulp, and immediately provide a cold, moist treatment for 90 to 120 days. Seeds that dry out will NOT germinate. It takes a long time for the seedling to emerge because of the long taproot that initially develops. To accelerate germination, supply bottom heat to the containers. Trees started from seed usually produce fruit in 5 to 8 years after planting, while grafted trees may bear fruit in 3 to 4 years.

Grafting: 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 rooted cuttings, hardwood and softwood cuttings, and T-budding produce poor results, while tissue-cultured, micropropagated plantlets have been difficult to grow out.

Problems

Pawpaws are generally pest-free plants. They 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 many insects and diseases and can be grown without pesticides.

Pawpaw is the exclusive larval (caterpillar) host plant for the zebra swallowtail (Eurytides marcellus), but their feeding on leaves rarely results in much damage to mature trees.

Japanese beetles occasionally damage leaves, and thrips can be a problem in greenhouse conditions. Ambrosia beetles sometimes kill stressed trees. A telltale sign of ambrosia beetles is the matchstick-like frass waste protruding from tiny holes on the trunk. For more information on ambrosia beetles, see HGIC 2018, Ambrosia Beetles.

A severe fungal disease, bordered leaf spot (Phyllosticta asiminae), occurs in humid climates and infects leaves and fruit. This disease causes hard black spots to form on the fruit skin, which often merge and leads to premature cracking. Leaves are affected too, but the tree is not killed. Some fungicides may control it, but there are no fungicides labeled for use on pawpaws.

Phyllosticta fungal disease complex produces black splotches on fruit.

Phyllosticta fungal disease complex produces black splotches on fruit.
Gregory Reighard, ©2022, Clemson University

Phyllosticta fungal disease complex produces black spots on leaves.

Phyllosticta fungal disease complex produces black spots on leaves.
Gregory Reighard, ©2022, Clemson University

A cosmetic fungal disease known as flyspeck (Zygophiala jamaicensis), has been reported on pawpaw. However, the fungus only grows on the surface of the fruit and does not prevent it from being edible.

Foxes, feral pigs, opossums, and raccoons eat the fruit. Deer do not feed on the leaves or twigs, but they will eat the ripe fruit. Sap beetles, bumble bees, and butterflies are also fond of ripe fruit once it falls to the ground.

For a video discussion of pawpaw featuring Greg Reighard, Professor Emeritus of Horticulture, see The Pawpaw Patch–Making It Grow.

References:

  1. Bratsch, A. 2006. Specialty crop profile: Pawpaw. Virginia Cooperative Extension Publ. No. 438-105, June 2006. 10 pp.
  2. Callaway, M. B. 1990. The pawpaw (Asimina triloba). Kentucky State Univ. Pub. No. CRS-Hort1-901T. 22 pp.
  3. Pomper, K., S. Crabtree and J. Lowe. 2021. Pawpaw. Kentucky State University pawpaw program. https://www.kysu.edu/academics/college-acs/school-of-ace/pawpaw/index.php
  4. Layne, D. R. 1995. Pawpaw. Purdue University Center for New Crops & Plant Products fact sheet. http://www.hort.purdue.edu/newcrop/CropFactSheets/pawpaw.html
  5. Peterson, R.N. 1991. Pawpaw (Asimina). Chapter 12. IN/ Genetic Resources of Temperate Fruit and Nut Crops. Tech. Comm. No. 290-XII, Feb. 1991 of International Society of Horticultural Science. Pp. 567-600.

Originally published 10/15

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