It is Time to Save the American Chestnut

American Chestnut History

• Pre-1900, American Chestnuts were the most populous tree in the Blue Ridge Mountains (between 25% to 40% of all trees)��
• Chestnuts were a keystone species, providing nuts for humans and wildlife and high quality lumber

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American Chestnut History

• A terrible blight hit starting around 1905 in NY

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• Caused by the importation of Asian Chestnuts that were easier to grow for nut production

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• Within the next 15 years, billions of trees had been wiped out

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American Chestnut History �(Whitetop Mountain)

The Goal – Breed the Large Surviving Americans (LSAs)

Normal American Chestnut Blight Reaction

Blight Reaction in Meadows of Dan LSA

Blight Reaction Mathews DOF Orchard

Why Us?

American Chestnut Cooperators’ Foundation

• Historical Champion of LSA Breeding

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• Started by Dr. Gary Griffen at Virgina Tech

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• They have produced superior American Chestnuts

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ACCF Issues

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• Believe that with genetic engineering, you can insert major resistance genes into chestnuts

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• Major setbacks in 2023

TACF Hybrid Program

TACF Problems

• Backcrossing assumed simplicity
• Assumption was that 2 or 3 Chinese genes were responsible for resistance
• There are actually hundreds of genes responsible for resistance
• Selection Problems
• Resistance is a function of genetics and environment
• Selection criteria at each generation was suspect

TACF Solution

• After 40 years of breeding, TACF had thousands of trees at hundreds orchards throughout the East Coast.

• TACF also has dedecated volunteers

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• TACF used the hybrids available in the orchards to build genetic models to select for better and better resistance at each generation

TACF RGS Model

This is where we need you!

• Several of my friends have been convinced that we should use the same modeling to breed the LSAs
• After several years of working with TACF, this program is starting

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Where we need help

• The hybrids TACF primarily uses in RGS are easily accessible in orchards
• The LSAs are largely still in the woods
• It will be a significant volunteer effort to identify the LSAs and get them out of the woods

Grow More Chestnuts to Find More Resistance

Starting now, we need to grow more Americans to find more resistant trees�� We have lots of nuts and growing instructions to give out today

Spring - Tissue Collection for DNA Testing

• The Virginia Chapter has a list of 50 LSA prospects
• For trees we know are alive, starting this Spring (May), we need to start organizing trips to the known trees to collect young leaf tissue for genetic mapping for trees we know are alive
• Leaf tissue collection volunteer list signup is in the back

Spring - Pollen Collection

• The Virginia Chapter has a list of 50 LSA prospects
• For trees we know are alive, starting this June, we need to start organizing trips to the known trees to collect pollen for controlled crosses
• Pollen collection volunteer list signup is in the back

Spring - Pollen Collection

• We will also collect pollen from known LSAs that are already in TACF’s genomic program

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• We will send that pollen to collaborators around the country to cross pollinate with new trees

Spring – Controlled crosses�

• Controlled Pollinations with other LSAs at Lesesne State Forest (June)
• Pollination Crew Signups are available

Summer, find and mark more LSAs

Summer, find and mark more LSAs

• Critical that we increase the diversity of the LSAs
• We will search out the known big trees to make sure they are still alive
• We will flag the trees to make sure we can find them in the future
• We need to talk to foresters and hunters to see what they know
• We will then chase the trees down in the summer
• Chestnut Chasers sign up is available

Long term, replicate field trials

• Longer term project
• LSA progeny from controlled crosses get grown out over five years in a field trial
• Trees are then inoculated with blight to test parent heritable resistance
• This is the LSA field trial at our place!
• Field trial signups available too!

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Fall, Harvest

• We need to harvest all the burs formed by the controlled LSA x LSA crosses we made!
• We need to help TACF collect all the burs we can for grafting and growing more chestnuts
• There are always several harvest sites: Lesesne, Johns’ Creek, and many others always need help!
• Sign up for Fall Harvest Interest!

Matthews Orchards

• Judge Matthews donated Matthews State Forest to VA DOF for chestnut work
• There are three orchards at Matthews, all need work
• The one that needs critical work is the DOF Backcross orchard

Matthews DOF Orchard

• Many superior trees
• Set up planted close together for a field trial
• Too many of the trees lived
• We know need to thin out to the select trees for nut production
• This is an immediate project (April this year)! Please sign up!
• If we can get the trees adequately thinned in 2026, we will have an abundance of nuts to harvest in 2027

Winter, Grafting

In grafting, you clone a select tree by taking a small stem (scion) and wrapping it tightly to a rootstock

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The scion and the rootstock will then fuse and grow together and the part above ground is a genetic clone to the original tree

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Winter, Grafting

• Large Survivors are too geographically distant to easily cross with one another
• Large Survivors in the woods are too tall and inaccessible to effectively pollinate.
• You need to graft to bring clones together to effectively be able to do the cross-pollinating breeding work

Winter, Grafting (Scion Collection)

• Go back to the trees that the Chestnut Chasers Flagged in the Summer
• Collect Scions for grafting
• Sign up for Scion Crew!

Winter Grafting, Workshops

• The last two years, I have been a part of a grafting workshop at Bedford (2024) and Penn State (2025)
• We need to organize grafting workshops here to teach more grafters the steps
• Please sign up for grafting workshop 2027 (Grayson County)!
• I also have instructions and scions if people want to try for themselves this year

The Winter, Spring, Summer, Fall cycle repeats for several years so that TACF can build the LSA model

The End Game

• We make the controlled crosses now that we have our LSA model

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• We plant the top 10% as predicted from the model for a 4^th Orchard at Matthews State Forest

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• This will be the very first large surviving chestnut orchard in the country with enhanced resistance

Questions?