Outlook for blight-resistant American chestnut trees
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Culminating 20 years of breeding efforts, in spring 2008, The American Chestnut Foundation (TACF) delivered its first 500 chestnuts to the USDA Forest Service for testing on National Forest lands. The expectation is that these seedlings will be more resistant to chestnut blight (Cryphonectria parasitica) than are pure American chestnut trees (Castanea dentata). Greater numbers of seeds will be distributed in coming years, as more trees start producing nuts and as these trees become larger. Meanwhile, the breeding program at TACF continues, incorporating different sources of resistance and broadening the genetic base by breeding to surviving American chestnut trees from Maine to Alabama. An additional challenge in the southern United States is the fact that American chestnut is highly susceptible to the root rot organism Phytophthora cinnamomi, which is found in warm, poorlydrained soils. Both Chinese (Castanea mollissima) and Japanese (Castanea crenata) chestnut trees are resistant to this soil pathogen. A volunteer member of TACF, Joseph B James of Seneca, SC, is cooperating with Clemson University scientist Steve Jeffers to breed American chestnut trees resistant to both blight and root rot. In addition, Scott Enebak of Auburn University is determining ways of keeping the root rot pathogen out of forest nurseries where chestnut seedlings are grown.