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Pawpaw Update: June 21, 2007

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.

Organic production possible

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.

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

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

Lewis and Clark recorded in their journal (18 Sept. 1806) how pawpaws helped save them from starvation.

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.

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

Freeze Damage!

April 7-9, 2007 freeze destroyed most of the pawpaw crop.

Research Update

Ornamental Pawpaws

DNA fingerprinting

Regional Variety Trial Summary

Acetogenin Update

KSU Ornamental Pawpaw Project

Started in 1995 with about 200 plants from Mr. Neal Peterson that were the result of a cross between Asimina triloba (female) x Asimina reticulata (pollen).

The genus Asimina

Other members of the Asimina genus that are native to the extreme southeastern states:

• A.incarna (Bartr.) Exell. (flag pawpaw)
• A.longifolia Kral, A. obovata (Willd.) Nash
• A.obovata Kral
• A.pygmaea (Bartr.) Dunal
• A.reticulata Shuttlw. ex Chapman
• A.tetramera Small (opossum pawpaw)
• A.parviflora (Michx.) Dunal (dwarf pawpaw)

KSU Ornamental Pawpaw Project

Started in 1995 with about 200 plants from Mr. Neal Peterson that were the result of a cross between Asimina triloba (female) x Asimina reticulata (pollen).

Red F1

Red F1

KSUOR001P

KSUOR002Y

KSUOR003Y

KSUOR004R

KSU Ornamental Pawpaw Project

Propagation a challenge

We will try a number of clonal propagation approaches

Research Update

Ornamental Pawpaws

DNA fingerprinting

Regional Variety Trial Summary

Acetogenin Update

DNA Fingerprinting

Dr. Li Lu, Co-Investigator of Biotechnology

Research Update

Ornamental Pawpaws

DNA fingerprinting

Regional Variety Trial Summary

Acetogenin Update

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

What is a Cultivar?

■ Cultivar = refers to a named group of plants within a cultivated species that is distinguishable by a character or group of characters and that maintains its identity when propagated either asexually (e.g. ‘Jonathan’ apple) or sexually (e.g. ‘Tendercrop’ snapbean)

Seedlings and Cultivars

Seedlings produce fruit in 5-8 years

Grafted cultivars can produce fruit in 3 years; know fruit quality

Takes about 5-6 years to reach full production

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

What cultivars should I plant?

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

Commercially Available Cultivars

Seedlings of 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 2002-2006

Pawpaw RVT Overview

Based on fruit size and quality the pawpaw cultivars: Potomac, Susquehanna, Wabash, Overleese, Shenandoah, NC-1, and Sunflower can be recommended.

Research Update

Ornamental Pawpaws

DNA fingerprinting

Regional Variety Trial Summary

Acetogenin Update

Pawpaw Anticancer Acetogenin Compounds

Annonaceous acetogenins

Long unbranched fatty acid chain

Present in twig tissues and recently found in fruit tissue

Anti-cancer activity

Sometimes suggested as a potential health problem

Atypical parkinsonism?

Brine Shrimp Test

The BST Results

High acetogenin cultivars:

NC-1, PA-Golden, Potomac, Susquehanna, Wabash, Overleese, Shenandoah, Taytwo, Taylor, Mitchell, Middletown, and Zimmerman

Low acetogenin cultivars:

Sunflower and Wells