Georgia News

GA-TACF Science Progress 2022

2022 was a very productive year for the Georgia chapter of TACF and its many citizen volunteers.  Here is a quick summary of progress, starting with a summary of what we’ve been able to accomplish in the breeding program since 2006.

Seed type
American chestnut C. dentata 123
F1 17
BC1 17
BC2 2
BC3 113
BC4 114
Chinese chestnut C. mollissima 31
Darling 58 (OXO) 7
Other (Quasi B1, C. henryi, C. pumila, etc.) 38
Summary of summer/fall 2022 breeding work:

11 backcross lines for blight resistance screening

4 backcross lines for Phytophthora root rot (PRR) resistance screening

4 backcross lines for both blight and PRR resistance screening

14 C. dentata or nearly 100% C. dentata lines for germplasm conservation

9 Asian lines for phylogenetic study of blight resistance

Total of 1234 seeds produced
Other key activities summer/fall/winter 2023

Grafting: Grafted 62 scions of pure C. dentata on C. mollissima root stock.  14 alive from 4 lines.  Also, scion material was sent to USFS for nut grafting (material from about 25 different C. dentata in GA was collected and sent in January 2023)

Pollen collection: Pollens collected, processed, and frozen from 27 trees (10 C. dentata, 14 “Best” backcross trees, and 3 F1s).

Best X Best crosses: While our Best X Best hand pollinations at UGA largely failed, our GA pollens were successfully used to produce at least seven crosses by the Tennessee chapter (more by Meadowview and CC chapters).

Small stem assays (SSAs): SSAs were completed on ~350 seedlings at Berry College (11 backcross lines plus controls). Small stem assay manuscript was published in Plant Disease (Conn, et al.). This Alternate SSA (AltSSA) method is beginning to be the standard for early blight screening in the TACF program. Winners going to Richards orchard.

Blight evaluations, orchard inoculations, and culling: Done at Roy Richards and Flint backcross seed orchards.

Tree mapping: Several new Castanea trees were catalogued and mapped, including one C. dentata in Oconee County and about 27 new C. dentata from recent TreeSnap observations.  See map here:

Germplasm conservationC. dentata seedlings from 2021 crop are being distributed to various germplasm conservation orchards for planting winter 2022-23.  Embryos from GA trees were successfully cloned from several sources by the Merkle UGA lab and some lines have been successfully transformed with the OXO gene.

Breeding orchard plantings: Trees were added for PRR screening at Flint North Ridge site in October 2022. Trees are ready for planting at Roy Richards seed orchard in early 2023.

Miscellaneous other:

Phylogenetic study: Seeds from C. mollissima, C. henryi, and C. seguinii were harvested for a collaborative phylogenetic study being organized by Jared Westbrook at TACF.

Tree searching: Testing of protocol is underway for locating new C. dentata using drones (Jack Rogers).

DNA analysis: A few samples of leaves were taken from key trees for DNA analysis.


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A good number of trees at this EKU site in KY originated in the GA-TACF breeding program! So, they are "our" trees, too! ... See MoreSee Less

A good number of trees at this EKU site in KY originated in the GA-TACF breeding program! So, they are our trees, too!Image attachmentImage attachment

3 CommentsComment on Facebook

That's awesome!

Got to love the reversed picture T-shirt.

Nice looking orchard

The American Chestnut Foundation is seeking scion wood from wild American chestnut trees from the southern population. Population studies have determined that trees found in western TN and KY, GA, AL, and MS represent the southern population and are the most genetically diverse. The objectives of this collection are to:

🌱Conserve genetic diversity of unique and underrepresented populations of American chestnut through grafting

🌱Grow these grafted plants in favorable conditions (including growth chambers) to promote flowering and ease of pollen collection

🌱Future utilization of pollen and flowers to outcross transgenic chestnut

Goals for 2023: Gather around 100 sources from the South

•Coordinate with Jamie Van Clief at for the collection of this scion wood.

•Scion wood collection should be done during winter dormancy only, which is commonly marked by the loss of leaves or brown leaves dangling (flagged) on their branches. Ideally, collected between December 2022–January 2023.

•It may be necessary to visit sites twice: once, before winter dormancy to ensure species can be identified to the American chestnut, particularly in areas where they co-occur with chinquapin. Second, when trees have gone dormant to collect scion wood.

•Scion wood should be at least 3 inches long and contain 1 or more unopened buds. With nut grafting, the diameter of the scion is not a concern, but larger buds with space in between buds are preferred.

•Collect ten pieces of scion wood per tree, when possible. At a minimum, we are looking for about fifteen buds. However, use judgment when collecting from small trees to not jeopardize the tree's survival by over-collecting.

•Take GPS coordinates from each tree using the TreeSnap application for smartphones ( or with a GPS unit or smartphone. Ideally, trees have already been identified and entered into TACF’s dentataBase.

•Place scion wood from a single tree in a one-gallon sealable bag.

•For each tree, place a note card in the bag containing: data collected, county, state, latitude and longitude.
Previously used for breeding or not: Yes, No or Unknown
TreeSnap ID or wild tree code from Regional Science Coordinator (if applicable)
Public or private land (Do Not Trespass!)

•Before sealing, place the card in the bag, then roll the bag from the bottom to the top to remove excess air.

•Do not write on the bag as even permanent markers will fade or be scratched off during handling and storage. Temporary writing on bags is fine, but do not rely on them for storage.

• Do not place a damp paper towel in the bag. Moisture from the towel commonly causes mold during storage.

•If desired place them in damp (NOT WET!) peat moss in the bag. The peat moss should be damp enough that you can squeeze it into a ball but not so damp you can squeeze water out of it.

•While in the field, store scion wood in a cooler with cold packs and place it in the refrigerator's crisper drawer until shipping. Do not place it in the freezer.

•Please ship scion wood no later than 2-3 weeks after collection.


Ship on Sunday through Wednesday via 2-day shipping to the attention of Chance Parker. Do not ship on Thursday or Friday. Coordinate with Chance and Jamie Van Clief so everyone knows what has been shipped. Ship samples on cold packs and in small foam cooler, if possible.


Sealable gallon freezer bags
GPS unit or smartphone with TreeSnap (
Permanent marker for making notes on cards
Notecards or paper
Pruning shears and/or pole, depending on tree size
Cooler and cold packs

About Scion Wood

While trees are grafted just as the rootstock buds start to grow, the buds on the scion wood must be dormant at the time of grafting. Thus, February is an ideal time to collect scion wood for spring grafting.

After cutting scion wood, it can be sealed in polyethylene bags to prevent moisture loss and stored for three months at 32°F until grafting. Storage at lower temperatures in home freezers can damage the buds. Temperatures warmer than 32°F will shorten the storage life of the scion wood. Using scion buds that have begun to grow while in cold storage will result in grafting failure.
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