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The North American pawpaw [Asimina triloba (L.) Dunal] grows wild in mesic hardwood forests of 26 states in the eastern United States, flourishing in deep, fertile soils of river-bottom lands where it grows as an understory tree or thicket-shrub (Kral 1960; Callaway 1990; Callaway 1993). Pawpaws can be grown successfully in USDA plant hardiness zones 5 (minimum of -29circ C) through 8 (minimum of -7circ C) (Kral 1960). This tree produces the largest edible fruit native to the United States; it may reach up to 1 kg in size (Darrow 1975). The pawpaw fruit has both fresh market and processing potential, with an intense flavor that resembles a combination of banana, mango, and pineapple. Natural compounds in the leaf, bark, and twig tissues of pawpaw possess insecticidal and anti-cancer properties (McLaughlin 1997). The unique qualities of the fruit, ornamental value of the tree, and the potential for useful bioactive compounds suggest that pawpaw has great potential as a new high-value crop.
Although pawpaw has great potential for commercial production, orchard plantings remain limited. Currently, most pawpaw fruit for sale are collected from wild stands in the forest. However, in a number of states, including Alabama, California, Kentucky, Maryland, Michigan, Missouri, North Carolina, Ohio, and West Virginia, in the United States, small private orchards, usually less than 1 ha in size, have been planted and will be coming into production soon. There are also pawpaw plantings in Italy (Bellini et al. 2003), China, Israel, Japan, Romania, Belgium, and Portugal. In the United States, pawpaw fruit and products are mainly sold at farmer's markets, directly to restaurants, and via entrepreneurs on the Internet. Pawpaw fruit were sold in 2003 at the Farmer's Market in Lexington, Kentucky, for $6.50 per kg. Local delicacies made from the fruit include pawpaw ice cream, compote, jam, and wine. However, at present the grower base is insufficient to establish a commercial processing industry.
Nursery wholesale and retail tree production represent an added economic opportunity for entrepreneurs beyond that of orchard production. Pawpaw trees currently sell for higher prices than most other fruit trees since they are attractive to homeowners in ornamental plantings, edible landscapes, specialty gardens, and habitat restoration (Layne 1996). In addition, Asimina spp. are suitable for butterfly gardens, as they attract the zebra swallowtail (Eurytides marcellus Cramer), for whom they are the exclusive larval host plant (Damman 1986; Haribal and Feeny 1998).
Many challenges are encountered in developing production practices for a new crop. Cultural practices can affect important aspects of plant growth and influence the overall dynamics of the production system. The objective of this chapter is to review the botany and horticulture of the pawpaw and to summarize recent research efforts that have been conducted in an attempt to develop production recommendations for this promising new crop.
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The objective of this chapter is to review the botany and horticulture of the pawpaw and to summarize recent research efforts that have been conducted in an attempt to develop production recommendations for this promising new crop.
Pawpaws have a well-established place in folklore and American history. "Where, oh where, is dear little Nellie (Sallie, etc.)? 'Way down yonder in the pawpaw patch." This traditional American folk song and dance was quite popular once and fall hunting for pawpaws in the woods is a cherished tradition for many rural families in the southeastern United States. The first report of pawpaw dates back to 1541 when followers of the Spanish explorer Hernando de Soto found Native Americans growing and eating pawpaws in the valley of the Mississippi (Pickering 1879). The Native Americans used the bark of pawpaw trees to make fishing nets. John Lawson (1709) in A New Voyage to Carolina referred to pawpaws "as sweet, as any thing can well be. They make rare Puddings of this Fruit." John Filson (1784), an early settler, promoter and developer of Kentucky, stated that "the pappa-tree does not grow to a great size, is a soft wood, bears a fine fruit much like a cucumber in shape and size, and tastes sweet." Daniel Boone and Mark Twain were reported to have been pawpaw fans. Lewis and Clark recorded in their journal (18 September 1806) how pawpaws helped save them from starvation. "Our party entirely out of provisions subsisting on poppaws. We divided the buiskit which amounted to nearly one buiskit per man, this in addition to the poppaws is to last us down to the Settlement's which is 150 miles. The party appear perfectly contented and tell us that they can live very well on poppaws." John James Audubon painted the yellow-billed cuckoo on a native pawpaw tree (ca. 1827). On 9 August 1882, three sons of Randolph McCoy (clan leader) were tied to pawpaw bushes and executed by the rival Hatfield family during the famous Hatfield-McCoy feud along the Kentucky-West Virginia border (Owens 1994). Several American towns, townships, creeks and rivers were named after the pawpaw during the 19th century.
Interest in pawpaw as a fruit crop was evident in the early 1900s (Little 1905; Popenoe 1916, 1917; Zimmerman 1938, 1941; Thomson 1974; Peterson 1991). At about this same time, interest in another native fruit, the blueberry (Vaccinium sp.), was also increasing. One reason for the failure of pawpaw to become as popular as blueberry was likely related to the rapid perishability of the fruit (Popenoe 1916, 1917). However, interest in pawpaw grew in the years between 1950 and 1985, nurtured