Grow more trees. Find rarer combinations.
Resistance is complex. The more well-documented American chestnuts we grow, the better our chance of finding families with unusually useful combinations of genes.
Give young chestnuts a strong start.
A four-foot by four-foot raised bed can hold four families of ten nuts each for roughly two growing seasons.
Families are separated and labeled within the bed. The loose, weed-managed soil encourages strong root systems and makes it possible to lift the trees bare-root after the second growing season. Those larger seedlings can establish more quickly when moved to a field trial in the fall.
Growing families is essential because natural selection alone has little room to operate. Most wild American chestnuts die back before reaching reproductive age, and the flowering survivors are often too isolated to exchange pollen effectively. Intentional growing and breeding recreate the population size and connectivity that the blight disrupted.
What can a leaf tell us about oxalic acid?
Clint Morse is exploring a simple leaf assay as one additional way to compare chestnut families—not as a replacement for genomic selection or field canker tests.
The chestnut blight fungus, Cryphonectria parasitica, produces oxalic acid during infection. The acid contributes to tissue damage and is one of the fungus's important virulence tools. That biology raises a useful question: do chestnut families differ in how much tissue damage they show after a standardized oxalic-acid exposure?
For this exploratory assay, leaves are collected from chestnuts growing in the family beds, pricked with a needle, and wiped with a controlled oxalic-acid treatment. About three hours later, the leaves are scanned and the damaged area is measured. Smaller lesions may be a useful signal of tissue tolerance.
Chinese chestnut reference
Leaf-tissue response provides a higher-resistance comparison group.
Chestnut 105
A family sample measured with the same exposure and scanning workflow.
Turn images into comparable scores.
Scanning and image analysis allow the assay to summarize many leaf disks into family-level patterns, while preserving the need for replication and cautious interpretation.
What this chart shows
The family scores are normalized to a Chinese chestnut reference. Higher bars indicate less modeled tissue injury under this particular assay and scoring method.
What it does not show
The chart does not establish whole-tree blight resistance, long-term survival, or breeding value by itself. It is one layer of evidence that should be checked against pedigree, genomic information, stem or bark assays, and field performance.
Why it may still help
When the same protocol is applied consistently across many families, it can highlight patterns worth investigating and help prioritize limited space and follow-up testing.
No single test saves a tree.
Restoration becomes credible when multiple kinds of evidence point in the same direction.
Pedigree
Known parents and family structure.
Genomics
DNA-based predictions from the RGS model.
Assays
Repeatable tissue or stem responses under controlled conditions.
Field performance
Growth, cankers, survival, and reproduction across years and sites.
Forty nuts can become a classroom, a nursery, and a scientific dataset.
Raised beds make it possible for families, schools, landowners, and volunteers to grow meaningful numbers of chestnuts in a small space.