NE1015: Biological Improvement, Habitat Restoration, and Horticultural Development of Chestnut by Management of Populations, Pathogens, and Pests
Statement of Issues and Justification
Before the introduction of chestnut blight, American chestnut was one of the most valuable trees in eastern North American forests. When Europeans first settled eastern North America, chestnut was a major and eminently notable forest tree everywhere from Ontario to Georgia. It was the one eastern forest tree that approached the dimensions of the gigantic Pacific Coast rain forest conifers; thus, it was referred to as the 'Redwood of the East'. Chestnut occupied a wide range of site types, ranging from mesic to xeric. Quality chestnut on mesic sites attained a clear trunk length of up to 72 feet with an overall height of 120 feet and a diameter of 5 feet. Dry, thin, acidic ridge top soils provided the poorest growing conditions, but chestnut still managed to grow to a height of 70 feet. The tree was prized for its high quality wood, tannin extracts, and nuts. Chestnut blight disease eliminated the American chestnut as a canopy species and elevated oaks as the most dominant tree group in the southern Appalachians. However, widespread oak decline has occurred in the southeastern U.S. over the past 20 years, leading to declining forests. It is believed that southern Appalachian forest ecosystems will not be considered healthy until chestnut can be reintroduced as a functioning component of that ecosystem. Loss of the American chestnut resulted in significant biological and economic changes. Replacement species generally include red oak, black oak, and chestnut oak, all much slower growing than chestnut. Return of chestnut to eastern forests could vastly improve existing forest stands, and positively impact wildlife, since chestnuts produce seed every year as opposed to oaks and hickories.The NE-140 Technical Committee was organized in 1982, and since then, members have worked cooperatively to investigate the complex issues involved with the biological improvement of chestnut, along with habitat restoration and horticultural development of American chestnut and chestnut cultivars. Environmental and land stewardship issues that are concerns to stakeholders are addressed by NE-140 through efforts to understand the ecology and biology of eastern North American forests following the loss of American chestnut. Control of chestnut blight disease through the use of hypoviruses and resistant chestnut trees may vastly improve forest stands in eastern North America, answering many concerns regarding forest ecology. Other important issues of this continued work are improved forest management, including biological-based controls of invasive insect and disease organisms threatening chestnut. This will serve as a model for natural resource managers. Food safety issues are addressed via the creation and use of IPM-based controls of both forest and orchard trees, reducing the use of pesticides. Increased use of chestnuts in the American diet will improve human health, since chestnuts are unique among nuts with fat content ranges from 1-10%, compared to 70% in most other nuts. The viability of rural communities will be enhanced through creation of a new horticultural chestnut market.
Restoration of chestnut as a timber tree and improving orchard chestnuts in the United States continue to be the long-term goals of the members of this regional project. To succeed in our efforts to achieve these long-term goals, continued activity of the award-winning NE-140 group is critical. NE-140 is working to successfully develop and deploy biological systems that protect natural resources and the environment. NE-140 must sustain its rapid, productive trajectory in order to develop effective, biological-based solutions to address the ecosystem disruption caused by invasion of the chestnut blight fungus (Cryphonectria parasitica) and death of billions of American chestnut trees (Castanea dentata).
In the shorter term, we continue to build on our understanding of two biological approaches to the control of chestnut blight disease: use of biocontrol agents to control the fungus populations, and tree breeding to improve the fitness of the trees. Efforts to understand the molecular, organismal, and ecological basis of C. parasitica infection, and the critical role of hypoviruses and defective mitochondria, are essential for successful development and deployment of IPM programs. NE-140 is further developing hypovirulent strains of C. parasitica for use in IPM programs to protect timber and orchard chestnut trees, and seeking environmentally safe techniques to control pathogens such as Phytophthora root rot and pests such as the oriental chestnut gall wasp.
Currently NE-140 is: 1. incorporating, by standard breeding and transgenic approaches, chestnut blight resistance and gall wasp tolerance into chestnut for planting in forests and orchards 2. working to conserve native Castanea population diversity for future use in forests and orchards, including working with the National Plant Germplasm System of the USDA to establish germplasm repositories in California and Missouri 3. studying the ecology and cultural requirements of chestnut in nurseries and natural settings, leading to the reintroduction of chestnut into the forest 4. testing new chestnut cultivars, systematically documenting information on existing cultivars, establishing germplasm repositories for cultivar material, and testing new orchard management methods to enable U.S. growers to compete against U.S. fresh market imports
NE 140 has broadened its membership over the past five years to reflect the increasing breadth of chestnut research activity and bring additional research expertise to bear. The members of this group are strongly dependent on each other for the success of their individual projects. Working collaboratively, they seek to reverse the effects of devastating pathogens, find ways of dealing with new imported pests, and conduct research in support of the nascent horticultural chestnut industry.
The technical feasibility of the research. NE-140 is one of the nation's most productive research groups. Over the last five years (1998-2002), publications included 86 research papers, book chapters, reviews, and popular articles (plus an additional 169 publications from 1993-1997). Due to the growing interest in chestnut throughout the U.S., NE-140 also has expanded the breadth of institutions, researchers, and research sites beyond the Northeast region to more effectively address the multiple issues and foci related to chestnut.
The advantages for doing the work as a multistate effort. The scope, breadth, and magnitude of the effort required to combat chestnut blight disease, address other critical pathogen and pest problems, understand ecosystem processes involved in reestablishment of chestnut in the natural forest, and develop chestnut as a new orchard crop alternative for growers are far beyond the capability of any individual researcher or institution. Combined talents in molecular biology, genomics, virology, entomology, pathology, ecology, and horticulture, available across many U.S. institutions and use of numerous test sites throughout the Northeast and into the Midwest (plus a site in California) are required to effectively address the issues facing NE-140.
What the likely impacts will be from successfully completing the work. Successful completion of NE 140 goals will lead to a number of positive impacts including: reestablishment of timber chestnut trees in eastern N. America; improved stand diversity of eastern hardwood forests; successful reintroduction of chestnuts into xeric sites formerly populated by oak species decimated by gypsy moth infestations, in order to provide mast and wood products; establishment of productive nut-bearing chestnut trees in both eastern and western N. A. where a new industry is rapidly developing; and, improved economic opportunities for chestnut growers in local and international markets.
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