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Pawpaw 101: Just the Basics

Kirk W. Pomper, Ph.D.

Principal Investigator of Horticulture/ Kentucky State University Adjunct Assistant Professor of Horticulture/ Univ. of Kentucky

Introduction:

What is Pawpaw?

Asimina triloba (L.) Dunal.

Native tree fruit in the southeastern U.S.

Fruit can weigh up to 2 lbs.

Botany and Genetic Resources

Asimina triloba is a member of the tropical Custard Apple or Annonaceae family.

custard apple (Annona reticulata L.)

cherimoya (A. cherimola Mill.)

sweetsop or sugar apple (A. squamosa L.)

atemoya (A. squamosa x A. cherimola)

soursop (A. muricata L.)

The Pawpaw Fruit

Tropical-like flavor and aroma resembles mixture of banana, mango, and pineapple.

Custard-like fruits are berries

The fruit is very nutritious and high in antioxidant activity.

Could be used in blended fruit drinks, ice creams, yogurt, etc.

The Potential of Pawpaw

Fresh market-unique flavor

Appearance-not unappealing

Post harvest handling issues

Potential for bruising after harvest Short shelf life of about 7 days at room temp Storage for 3 wks under refrigeration

Short shelf life of about 7 days at room temp

Storage for 3 wks under refrigeration

The Potential of Pawpaw

Processing pulp

Labor intensive

KSU Land Grant Program Pawpaw Ice Cream!

4 cups milk

4 cups cream

3 cups sugar

1-2 cups pawpaw pulp

Dissolve sugar completely in the milk. Sugar dissolves faster if milk is lukewarm. Stir in cream.

Stir thawing pawpaw pulp into a small amount of ice cream mix. When smooth, add pawpaw to remaining ice cream mix.

For best results: Mixture should be 10-15% pawpaw pulp, i.e., add 1 cup pulp to 9 cups ice cream mix (10%), or 1.5 c. pulp to 8.5 c. ice cream mix (15%).

Thaw pulp gently – in refrigerator a while, just until it begins to soften. (Or partially thaw very carefully in a microwave, using short bursts on very low power, turning pulp frequently. Do not overheat!) Start stirring pulp into ice cream mix while it is still partially frozen, and stir to break up lumps and finish melting the pulp. Thawped pulp will oxidize and develop a bitter flavor very quickly when exposed to air.

Copyright by Kentucky State University 2004

The Potential of Pawpaw

Gourmet market

Fresh market fruit at farmers markets, restaurants, internet sales

frozen pulp

Future markets

Grower cooperative, Melissa's, Kroger

Where Are We in Terms of Developing a Pawpaw Industry?

Orchard (cultivars) vs. wild collected fruit

Private orchards established AL, CA, KY, NC, MD, MI, MO, OH, and WV.

Ohio Pawpaw Growers Association

Ohio Pawpaw Festival

LAKE SNOWDEN ALBANY OHIO

Pawpaw Products

Pawpaw ice cream and other menu items are being sold at gourmet restaurants.

Pawpaw fruit are being sold at farmers markets, such as the Lexington Farmers Market, and on the Internet.

New pawpaw products will be sold by individuals next year, including:

Pawpaw wine and pawpaw hot sauce

Pawpaws in the Wild

• A.triloba is usually found in the forest understory in hardwood forests
• Clonal reproduction by root suckering

You may not find many fruit (shade, self-incompatibility, lack of pollinators)

History of the Pawpaw

In 1541 Spanish explorer Hernando de Soto found Native Americans growing and eating pawpaws in the valley of the Mississippi.

John Filson (1784), an early settler in Kentucky stated: “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 pawpaw fans.

History of the Pawpaw

Lewis and Clark recorded in their journal (18 Sept. 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.”

Hatfield family photo courtesy of McDowell County Historical Society

Pawpaw Tree Incident (Marker Number: 2047)

County: Pike Location: Near Buskirk, KY 1056

Description: This episode is result of August 1882 election-day fight. Tolbert, a son of Randolph McCoy, exchanged heated words with Ellison Hatfield, which started a fight. Tolbert, Pharmer and Randolph McCoy Jr. stabbed Ellison to death. Later the three brothers were captured by Hatfield clan, tied to pawpaw trees, and shot in retaliation. Presented by Pikeville-Pike County Tourism.

Efforts to domesticate the pawpaw began early in the 20th century

In 1916, a contest to find the best pawpaw was sponsored by the American Genetics Association.

Sponsors thought that “intelligent breeding” would result in commercial quality varieties and an industry would begin (Popenoe 1916, 1917).

A pawpaw industry did not develop.

At about this same time, interest in another native fruit, the blueberry was also increasing. One reason for the failure of pawpaw to become a popular as blueberry was likely related to rapid perishability of fruit (Popenoe 1916, 1917).

One reason for the failure of pawpaw to become a popular as blueberry was likely related to rapid perishability of fruit (Popenoe 1916, 1917).

New Interest in Pawpaw

From 1950 and 1985, interest grew nurtured by the enthusiasm of individuals in the Northern Nut Growers Association (Peterson 2003).

The PawPaw Foundation was founded in 1988, by R. Neal Peterson.

In 1990, a full-time pawpaw research program was initiated at Kentucky State University by Brett Callaway (Callaway 1992) and was expanded by Desmond Layne from 1993 to 1997 (Layne 1996) and has been under the direction of Kirk Pomper since 1998 (Pomper et al. 1999).

Pawpaw Production

KSU Pawpaw Objectives

1. conduct a variety trial at KSU in cooperation with other sites across the nation
2. examine flowering, fruit set, and ripening
3. improve clonal and seedling/rootstock propagation methods
4. characterize the morphological and molecular variation in the germplasm collection
5. develop organic production methods

Pawpaw Acetogenin Compounds

Annonaceous acetogenins

Long unbranched fatty acid chain

Present in twig tissues and recently found in fruit tissue

Potential anti-cancer activity

Unknown if potential health problem

Atypical parkinsonism?

USDA National Clonal Germplasm Repository for Asimina spp. at KSU

In 1994, KSU was approved as the USDA National Clonal Germplasm Repository for Pawpaw (Asimina species), or gene bank

The orchards at KSU contain more than 2000 accessions sampled from native stands from 17 different states in the papaw's native range.

Pomper et al., 2003. J. Amer. Soc. Hort. Sci. 128:521-525.

What cultivars should I plant?

Pawpaw Regional Variety Trial Cooperators and Cooperating Institutions

Conceived by R. Neal Peterson (PawPaw Foundation) and Desmond Layne (then KSU)

Contains 10 cultivars and 18 selections from R. Neal Peterson.

Materials and methods

28 selections, 10 named varieties, 224 total grafted trees on PPF seedling rootstock (half-sib seed)

■ Established in March 1998 at the KSU Research and Demonstration Farm in Frankfort, Kentucky in a Lowell silt loam soil (pH 6.9)

Spacing 2 m (6.5 ft) between trees, 5.5 m (18 ft) between rows

Some Desirable Pawpaw Tree characteristics

Small tree size, easier harvest

Precocious bearing, 4 years or less

Vigorous growth with low to medium inputs

Open branching with strong crotch angles

High flower density

High fruit set under natural pollination

Consistently high fruit yields

Cold hardiness and drought tolerance

Some Desirable Pawpaw Fruit Characteristics

FRUITFULNESS over 40 fruit per tree FLAVOR sweet, firm texture, delicate blend of flavors, rich but not cloying, no bitter aftertaste FLESHINESS

sweet, firm texture, delicate blend of flavors, rich but not cloying, no bitter aftertaste FLESHINESS visually: mostly flesh. by weight: less than 5% of the fruit is seed FRUIT SIZE over 10 ounces

SEEDS

over 45 seeds per oz., av. seeds as small as 3/4" (2 cm) long APPEARANCE bright clear colors, no brown mottling (ripe); even, symmetrical PECULIARITIES SKIN: waxy/ fuzzy/ thick and hard/ yellow/ bluish. FLESH (ripe): white/ pink/ red. SEEDS: in a single row. RIPENING TIME: early / late KEEPING ABILITY: 2+ in refriger.

Commercially Available Cultivars

Seedlings from Collections

BEF = Blandy Experimental Farm Collection, Boyce Va.

GAZ = George A. Zimmerman Collection., Linglestown, Pa.

RS = Ray Schlaanstine Collection, West Chester, Pa.

Fruit Production on Mature Trees

Fruit Production on Mature Trees

Fruit Production on Mature Trees

Fruit Production on Mature Trees

Establishing A Pawpaw Orchard

“Pawpaw Planting Guide”

Site

air drainage (frost)

deep, fertile, well-drained soil, pH 5.5-7.0

water source for irrigation

Pawpaw Propagation and Nursery Sources

Historically, pawpaws have been a difficult tree species to propagate

Seed requires stratification and is desiccation sensitive

Commercial clonal propagation of cultivars is via chip budding onto seedling rootstock

Many nurseries grow pawpaw seedlings in containers

High prices for seedling and grafted trees are limiting the development of an industry

Seedlings $5.00-$10.00

Grafted trees $15.00-$25.00

Establishing a Pawpaw Orchard

Pawpaw will fruit in the shade, optimum yields are obtained in open exposure

Shading recommended the first year

Irrigation should be provided at least the first two years

Pawpaw Pruning

8' between trees, 18' between rows

295 trees/ac

Tree seldom grow taller than 25 feet

Fertilization and Irrigation of Pawpaw

Trickle Irrigation:

emitters (1 gal/hr) with 2 emitters/tree

about 240 gal/tree/yr.

Fertigation: Peters 20-20-20 (3 times each yr.)

0.6 oz N/tree/yr.

Granular (10-10-10)

1 oz N/tree/yr., 2 oz N/tree/yr. after two years

Pawpaw Pests

Organic production possible?

Some Past Problems

Japanese beetles

Zebra swallowtail butterfly-not necessarily a pest

Talponia plummeriana - pawpaw peduncle borer

New Pawpaw Pests?

Leaf and fruit spot (Phyllosticta)

New Pawpaw Pests?

Asian Ambrosia Beetle Xylosandrus crassiusculus

New Pawpaw Pests?

Asian

Ambrosia

Beetle

Xylosandrus crassiusculus

Flowering Time and Harvest

The North American Pawpaw, Asimina triloba:

Cross-pollinate

Pollinated by flies and beetles Ripe fruit should yield when squeezed and give way with a gentle tug Color change not a reliable indicator of ripeness Fruit may be harvested from the same tree over several weeks

Ripe fruit should yield when squeezed and give way with a gentle tug

Color change not a reliable indicator of ripeness

Fruit may be harvested from the same tree over several weeks

Pawpaw RVT Overview

There is great variation in fruit size, yield, and quality among the pawpaw selections examined

About 4 to 5 years to come into production

A number of pawpaw selections in the trial show promise for production in Kentucky [Shenandoah, Sunflower, Overleese, NC-1]

Availability of some PawPaw Foundation selections a problem (4-2, 1-7-2, 10-35)

Pawpaw Information Web Site Frankfort, Kentucky

Pawpaw Links Personnel Kentucky Nut Growers Spring Meeting NEW -n BIO 495: Topics in Biology- Understanding Biotechnology Spring Semester 2005

BIO 495: Topics in Biology-Understanding Biotechnology Spring Semester 2005

Are genetically engineered fruits and vegetables safe to eat? What is the Human Genome Project? How is DNA finger printing done in forensics? These and other topics will be covered in a new course entitled BIO 495: Topics in Biology-Understanding Biotechnology at Kentucky State University.

These and other topics will be covered in a new course entitled BIO 495: Topics in Biology-Understanding Biotechnology at Kentucky State University. These and other topics will be covered in a new course entitled BIO 495: Topics in Biology-Understanding Biotechnology at Kentucky State University.

3-month hours Lecture: Tuesday and 1 Thursday 5:00 to 6:30 pm Laboratory: Wednesday 5:00 to 0:00 pm Pre-course: Genetics Bio 307 or consent of instructor Please contact Dr. Mark Pomer of 300-657-6540 or kpomer@ginest.org to info@ginest.org

New Biotechnology course offered! NEW

Pawpaw in the News NEW

Pawpaw Commercial and Video

Pawpaw Research at Kentucky State University

Reports and Publications

PowerPoint Presentations Pawpaw FAQ Planting Guide Cultivars NEW Nurseries Description of Fruit and

Pawpaw Program

Kentucky State University has the only full-time pawpaw [Asimina triloba (L.) Dunal] research program in the world as part of the KSU Land Grant Program. Pawpaw research efforts are directed at improving seed and clonal propagation methods, developing orchard management recommendations, conducting regional variety trials, understanding fruit ripening processes, developing fruit storage techniques, and germplasm collection and characterization of genetic diversity. KSU also is the home of the PawPaw Foundation, a nonprofit organization dedicated to the research and development of pawpaw as a new fruit crop. Over 150,000 visitors since the website was placed on the internet!

Over 150,000 visitors since the website was placed on the internet!

http://www.pawpaw.kysu.edu/