The American chestnut tree & chestnut blight

Why is restoration of the American chestnut so important?

The American chestnut was an important foundation species in eastern forests before getting wiped out by an invasive pathogen. With restoration, we have the opportunity to reverse a catastrophic loss facilitated by human action. Restoration of the American chestnut would provide a valuable food source for wildlife and humans, a prized timber product, and the opportunity to sequester carbon and to help mitigate climate change.

How was chestnut blight introduced? What causes the blight? Where is it from? How did it get here?

The chestnut blight fungus, Cryphonectria parasitica, was accidentally imported on plant material in the late 19th Century and first identified as a new pathogen in New York City in 1904. The blight—an Asian fungus to which our native chestnuts have very little resistance—spread quickly. By 1950, the foundation species that could once be found across 180 million acres of eastern forests had disappeared. Only shrubby sprouts remain, growing from the still-living roots, which also quickly become infected.

I thought the American chestnut was extinct, but I saw one the other day. How can that be?

It is a common misconception that the American chestnut is extinct. In fact, there are still millions of American chestnut sprouts throughout the native range, mostly in forested areas. Unfortunately, these sprouts rarely survive to maturity and for that reason we consider the American chestnut to be “functionally extinct” in the wild. These survivors, however, make our breeding program possible. Very few of these small sprouts will live long enough to flower, and when they do, they tend to die fairly quickly. Very few surviving American chestnut trees are producing nuts and it is unclear if or how long it will take for these small sprouts to die out.

What do I do if I think I found an American chestnut?

Please let us know if you think you have found an American chestnut by submitting a Tree Locator Form and leaf sample. We are always working to expand our database of known chestnut trees across the native range. Samples should include leaves and stem/twig from the tree in question, as well as a completed Tree Locator Form.  For more information on how to send in a leaf sample for proper identification, read our Identification page.

The American Chestnut Foundation

What does The American Chestnut Foundation do?

The mission of The American Chestnut Foundation (TACF) is to restore the American chestnut tree to its native range. TACF is restoring a species, and in the process, creating a template for restoration of other tree and plant species. We operate the Meadowview Research Farms in Meadowview, VA and rely on an expansive network of volunteer state chapters to advance our work.

How is TACF restoring the American chestnut?

TACF engages in a multi-pronged effort to create a disease-resistant American chestnut, including traditional breeding techniques, genetic modification, and reduction of fungal virulence.

The majority of TACF staff and volunteers are involved in a traditional breeding approach. Requiring a minimum of six generations of breeding, progeny from this program are selected at each generation to exhibit American characteristics and some level of blight resistance. Recent efforts include “best-by-best” crosses between individuals with high resistance. In addition, efforts are made to increase the range-wide genetic diversity of this growing population of trees. 

TACF is also working with a variety of scientific partners to develop transgenic (introducing genes from other plant species) and cisgenic (introducing genes from other chestnut species of the same genus) methods to increase blight resisitance, as well as other genetic methods such as RNAi (RNA interference) to impede growth of the blight fungus.

No matter the method, whether used  independently or in combination, the goal is to produce American-type chestnuts capable of surviving and reproducing in the forest unassisted.

In addition to improving disease-resistance, TACF and its affiliates are working to conserve the genetic diversity of the species, assess susceptibility to other pests and pathogens (in addition to chestnut blight), and to understand the ecology of the species in order to prepare for landscape-scale reintroduction.

What do TACF State Chapters do?

TACF state chapters are the backbone of a breeding program for regional adaptability and are essential partners in the effort to capture sufficient genetic diversity to permit long term survival of the species. Chapters participate in TACF’s breeding program, manage plantings, inventory wild trees, participate in outreach events, and give talks and presentations in their local communities. Select ‘Find a Chapter’ in the main menu or contact your local chapter to learn more.

How are potentially blight-resistant chestnuts being produced and tested?

Testing of potentially blight-resistant chestnuts is conducted primarily using progeny testing at our Meadowview Research Farms, as well as in partnership with cooperators assisting in a formal, rigorous testing program. We are also developing genomic tools to help better assess this generation of chestnuts by identifying genetic markers for resistance. In addition, we ask any member with potentially blight-resistant plantings to report back regularly on the performance of their trees.

Why can't you just take resistance genes from the Chinese chestnut and put it into the American chestnut through gene splicing?

One of the main roadblocks to this approach is that we have not yet isolated all the genes associated with blight resistance in the Chinese chestnut. TACF has made substantial progress in identifying candidate genes from Chinese chestnut that may contribute to blight resistance. We are collaborating with researchers from Virginia Tech to validate whether these genes play a role in blight resistance.

Does TACF have other goals beyond breeding blight-resistant American chestnut trees?

In addition to increasing blight resistance, we are working to incorporate resistance to Phytophthora root rot, conserve native American chestnut germplasm, educate the public, and collaborate on many other projects to support the overall restoration of the species.

What is hypovirulence and how is it used?

There is a type of virus, called a hypovirus, which attacks the blight fungus. These viruses reduce the virulence of the fungus, often reducing the severity of resulting blight cankers. In the US, hypovirulence works when applied to a given tree and under certain circumstances, but has not yet been shown to spread on its own. Research is on-going to determine how hypovirulence may contribute to the restoration of American chestnut.

Are there scientific reviews of TACF's work?

Since 1983, the work of TACF has resurrected hope that the American chestnut can eventually be restored as a foundation species in the eastern deciduous forest.

As The American Chestnut Foundation continues to evolve we seek to have our breeding techniques and scientific objectives periodically vetted and reviewed by experts in the field. This is an ongoing practice through TACF’s collaborations with academic researchers and government partners, as well as through formal, in-person Science Reviews which thoroughly analyze research strategies and methods.

Science Reviews have been performed in 1999, 2006 and 2018.

TACF – 1999 Science Review

TACF – 2006 Science Review

TACF – 2018 Science Review

Does TACF receive federal money and abide to the USDA Nondiscrimination Statement?

TACF receives grant funding from the USDA.

With that, we abide by the USDA Nondiscrimination Statement:
In accordance with Federal civil rights law and U.S. Department of Agriculture (USDA) civil rights regulations and policies, the USDA, its Agencies, offices, and employees, and institutions participating in or administering USDA programs are prohibited from discriminating based on race, color, national origin, religion, sex, gender identity (including gender expression), sexual orientation, disability, age, marital status, family/parental status, income derived from a public assistance program, political beliefs, or reprisal or retaliation for prior civil rights activity, in any program or activity conducted or funded by USDA (not all bases apply to all programs). Remedies and complaint filing deadlines vary by program or incident.

Persons with disabilities who require alternative means of communication for program information (e.g., Braille, large print, audiotape, American Sign Language, etc.) should contact the responsible Agency or USDA’s TARGET Center at (202) 720-2600 (voice and TTY) or contact USDA through the Federal Relay Service at (800) 877-8339. Additionally, program information may be made available in languages other than English.

To file a program discrimination complaint, complete the USDA Program Discrimination Complaint Form, AD-3027, found online at How to File a Program Discrimination Complaint and at any USDA office or write a letter addressed to USDA and provide in the letter all of the information requested in the form. To request a copy of the complaint form, call (866) 632-9992. Submit your completed form or letter to USDA by: (1) mail: U.S. Department of Agriculture, Office of the Assistant Secretary for Civil Rights, 1400 Independence Avenue, SW, Washington, D.C. 20250-9410; (2) fax: (202) 690-7442; or (3) email: program.intake@usda.gov.

USDA is an equal opportunity provider, employer, and lender.

Does TACF provide auxiliary aids to qualified persons with disabilities?

Yes. If you need an auxiliary aid such as an online document read aloud to you, please contact our main office at 828-281-0047 or chestnuts@acf.org.

Where to get & how to grow American chestnut trees

How do I purchase American chestnuts?

The American Chestnut Foundation is excited that you want to support its mission to restore the American chestnut by planting chestnut trees. The two types of plant material available to current members of TACF are “wild-type” American chestnut seedlings and hybrid American chestnut seeds with increased blight resistance. Both are only available in the spring.

To learn more, visit the American Chestnut Seeds & Seedlings page.

Where should I plant American chestnuts?

To start, you’ll need well-drained, somewhat acidic soil. You can have a soil test conducted by your local university, extension agent, or environmental laboratory. A soil pH of 4.5 – 6.0 is best. For the trees to flower they need full sun, and for viable nut production you need at least two trees for cross-pollination.

How do I plant chestnuts?

There are many ways to do this. One method is direct-seeding chestnuts in the spring, as soon as you can work the soil. Don’t plant the seed deeper than about one inch in the ground, and protect it from predation and weeds. You can also start seeds in pots and plant the resulting seedling outside later in the spring, or in the fall. You can find more information about planting on the Growing Chestnuts page and the following fact sheets.

How to Grow Your Chestnuts

Planting American Chestnuts in Pots: Tips for a Successful Growing Experience

What is a wild-type American chestnut?

A wild-type American chestnut tree has not been intentionally hybridized with other chestnut species or genetically modified. These are sometimes referred to as “pure” American chestnuts but it’s important to remember that all nine species of chestnut worldwide (the genus Castanea) can hybridize with each other in the wild and some wild trees may be natural hybrids.

Why should I plant "pure" (wild-type) American chestnuts instead of waiting until the blight-resistant material is available?

There isn’t really any drawback to planting pure (wild-type) American chestnuts.  In fact, there are some great reasons to plant American chestnuts:

  1. To help preserve a native population of trees and the genetic diversity of the species;
  2. To learn how to grow, care for, and maintain American chestnut trees on your unique site.

There are worms in my chestnuts! What are they and how do I get rid of them?

The worms that are sometimes found in chestnuts are larvae of the chestnut weevil. There are two species: the ‘lesser’ and the ‘greater.’ The best way to control their proliferation is by collecting all of the fallen nuts in the fall to interrupt their life cycle. The nuts may be heat-treated to kill the larvae and prevent them from developing while in storage.