What If Gone

Species → American Chestnut

American Chestnut

Castanea dentata

More than 3 billion trees before 1900, making up about 25% of the…
Extinction risk Critically Endangered
Foundation speciesTemperate forestFungal diseaseExtinction
American Chestnut (Castanea dentata)
Photo: Rbreidbrown, Wikimedia Commons (CC BY-SA 4.0)

What if it disappeared?

Impact Major
Over 46 years

A fungus native to Asia, first discovered in 1904 on chestnuts at the Bronx Zoo, killed more than three billion trees within half a century — reducing the American chestnut from a dominant tree making up a quarter of its range's canopy to little more than an understory shrub.

Documented
Detail

SUNY College of Environmental Science and Forestry (ESF) — The American Chestnut Project History.

The pathogen, Cryphonectria parasitica, arrived on Japanese chestnuts imported for horticultural purposes, possibly as early as 1876. Having co-evolved no natural resistance in the American species, it spread with extraordinary speed across the tree's entire range — one of the best-documented forest disasters in North American history.

Withdrawal of support for the GMO project

The conservation organization most invested in saving the species withdrew its support for the genetically engineered Darling 58 chestnut, presented for years as the most promising restoration solution — expanded trials revealed weaker growth, higher mortality, and disease resistance far more variable than advertised.

Documented
Detail

The American Chestnut Foundation (décembre 2023). Annonce du retrait de soutien au projet Darling 58/SUNY-ESF.

The organization cited disappointing results across several external test sites in 2023, along with a laboratory error that led to the Darling 54 line being mistakenly used instead of Darling 58 in some trials. SUNY-ESF is nonetheless continuing its own research and deregulation efforts — a disagreement between partners that illustrates how much more uncertain a heavily publicized biotech solution can turn out to be once tested at scale.

Then, Long Island

Across more than 6,000 leaves inspected, none of the three leafminer species that fed exclusively on American chestnut were found — half a century after a previous survey had recorded all three, a sign that these specialist insects have vanished along with their host tree.

Extrapolated
Detail

Extrapolation à partir de Hough, K.E., Eiseman, C.S., Perreault, S., McGuinness, H., Burke, R.L. et Nieto-Fernandez, F.E. (2024). Survey of Leafminers on American Chestnut and other Castanea spp. (Fagales: Fagaceae) on Long Island, NY. Environmental Entomology, 53(4), 659–664 — un résultat négatif sur un seul site, pas encore une confirmation d'extinction à l'échelle de l'aire historique.

A 1978 survey had recorded 29 leafminer species using chestnut as a host plant, three of them feeding exclusively on this one species. Repeating that same fieldwork on Long Island's surviving chestnuts, the authors found none of these three specialist species — a negative result that does not formally prove extinction, but is consistent with it.

What's missing to confirm it: A search covering the chestnut's entire historic range, rather than a single Long Island site, before formally concluding extinction rather than mere undetected extreme rarity.

Documentation

Last verified: August 14, 2026