![]() These hybrids were then repeatedly backcrossed to American chestnut and screened at each step to produce a blight-resistant American chestnut that retained no distinguishable physical characteristics of Chinese chestnut. Chinese chestnut, which are resistant to the blight, were crossed with American chestnut to produce blight-resistant trees that are 50% American and 50% Chinese. ![]() ![]() In 1989, the American Chestnut Foundation (TACF) established a breeding program at the Wagner Research Farm in Meadowview, Virginia. Breeding and genetic engineering of blight-resistant American chestnut trees holds much promise. Researchers, the US Forest Service, non-profit organizations like the American Chestnut Foundation, and volunteers have made great efforts to prevent the complete loss of the species. Despite this, we are in a time of great optimism for restoring a once prominent feature across eastern deciduous forests. Moreover, discovering that the American chestnut is also vulnerable to a root disease caused by the fungal pathogen Phytophthora cinnamomi, presents another hurdle for their recovery (Gustafson, 2022). Because the fungal spores that cause the disease are wind-dispersed and can be harbored on many hosts, eradicating the pathogen is unfeasible. Restoring the ‘Redwoods of the East’ across their historical range is an arduous journey that will likely take decades. Is There Hope for the American Chestnut? Skip to Is There Hope for the American Chestnut? Although this cycle of death and rebirth has prevented the species from numerical extinction, American chestnut has been considered functionally extinct for decades. Trees are killed before reaching reproductive maturity (Henderson, 2023), reducing a once prominent canopy tree to an understory shrub. However, as the sprouts age, furrows in the bark develop, allowing the pathogen to enter and reinfect the new trees. In these instances, the root system continues to produce sprouts. In most cases, these cankers kill the cambium, eventually girdle the tree, and kill trees within three years of initial infection (Jeffries, 2014).īecause the pathogen does not kill the underground root system, chestnut blight infection is not always an immediate death sentence. Spores invade injuries or these furrows in the bark, leading to the development of cankers ( Fig. When young, American chestnut trees has impenetrable bark to the spores, but as they mature, the bark naturally develops deep vertical furrows or fissures ( Fig. The pathogen spreads via wind-borne fungal spores or are vectored by birds and mammals (Scharf, 2011). Today, American chestnut is considered functionally extinct in the forests it once dominated. By 1950, the blight had spread through much of its range, infecting more than 80% of mature American chestnut trees (Henderson, 2023). It was first detected in New York in 1920 however, the initial introduction could have occurred as early as 1876 with the first imports of Chinese chestnut ( Castanea mollissima) and Japanese chestnut ( Castanea crenata) nursery stock (Anagnostakis, 2000). ![]() With its strong, rot-resistant wood and abundant annual crop of nutrient-dense chestnuts, the American chestnut was once an invaluable hardwood for humans and wildlife before the chestnut blight decimated its populations in the early 1900s.Ĭhestnut blight is a canker disease caused by a fungal pathogen in East Asia. ![]() Their historical range stretched across 29 states, extending into the southeastern deciduous forests of Canada ( Fig. American chestnut ( Castanea dentata) once dominated portions of eastern North American forests and were considered the "redwoods of the East" ( Fig 1.). ![]()
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