Scientists & Staff

Current Research

My primary research and development efforts are focused on development, improvement, and production of baculoviruses that can be used to control invasive forest inset pests. In addition, I am leading an effort to restore the American elm to forested landscapes. Current efforts include:

  • Development of improved strains of the Lymantria dispar nucleopolyhedrovirus (LdMNPV)
  • Studies to understand a host's initial defenses to viral infection
  • Development of cell culture bioreactor production methods for LdMNPV
  • Generation of clonal L. dispar cell line that produce high levels of LdMNPV polyhedra
  • Determine if the browntail moth baculovirus, Euproctis chrysorrhoea, can be used in browntail moth infested areas to control this pest
  • Restoration of the American elm in forested landscapes

Research Interests

Future work will include efforts to identify microbial pathogens that infect the emerald ash borer and to develop methods of using the microbial agents to address the emerald ash borer problem.

Why This Research is Important

Invasive insects, plants, and microbes have had and continue to have a significant deleterious impact on U.S. forests. It?s estimated that approximately 50,000 species of plants, microbes and animals have been introduced into the U.S. Most of the invertebrate animal (e.g., gypsy moth, zebra mussel) and microbe (e.g., Ophiostoma novo-ulmi, Nectria coccinea) introductions were accidental, whereas vertebrate animal (e.g., cattle, poultry) and plant introductions (e.g., corn, wheat) were mostly intentional. The economic impact of 79 nonindigenous species over the period from 1906-1991 was estimated by the Office of Technology Assessment to be $97 billion in damages. More recently, it?s estimated that economic damages caused by nonindigenous species and costs for control and management of these species exceed $137 billion per year. Native forest insect pests and diseases also cause losses of approximately 18% of forest products (e.g., lumber, pulp) valued at approximately $9.8 billion annually. Due to the negative impact of invasive insects and diseases on the nation?s forests and urban trees efforts are needed to develop means of ameliorating the negative impacts of invasives.

Professional Organizations

  • American Association for Virology (1990 - Present)
  • Society for Invertebrate Pathology (SIP) (1992 - Present)

Featured Publications & Products

Publications & Products

National Research Highlights


Forest Service scientists develop a cold-hardy American elm tree

Year: 2017

Dutch elm disease largely eradicated mature elm trees from the eastern U.S. in the 1900s. Forest Service scientists are working to create site-adapted Dutch elm disease tolerant elm trees capable of tolerating the cold winters of the Chippewa National Forest in northern Minnesota.

1: Two American elm trees tree on left healthy with dark green foliage while tree on right is diseased and exhibiting light yellow foliage.  
2: Variability in American elm leaf color associated with infection by Candidatus. Phytoplasma trifolii  with leaves on left collected from an infected tree while leaves on right were collected from a healthy tree.

Identification of a clover proliferation group phytoplasma as the probable cause of American elm Ttee mortality

Year: 2017

Forest Service scientists observed premature canopy decline symptoms in elm trees within their research plantations in midsummer 2016. They attributed canopy decline symptoms to a phytoplasma in the clover proliferation group previously not reported to impact forest trees. Mitigation approaches are currently being undertaken.

Photo (1) USDA employee inoculating an American elm tree with the Dutch elm disease fungal pathogens. 
Photo (2) Healthy American elm tree (left) and a tree that has succumb to DED (right).

Forest Service moves American elm tree a big step closer to landscape restoration

Year: 2017

Over the past several decades, mature American elm trees have virtually disappeared from city streets and eastern forests as a result of Dutch elm disease. Forest Service scientists are on the cusp of developing sufficient genotypes to successfully restore new selections of American elm back to the landscape. Dutch elm disease inoculation trials initiated in Ohio in June 2016 yielded American elm cultivars that exhibit low levels of Dutch elm disease-induced decline one year later.

American elm cuttings growing in the greenhouse. Kathleen Knight, U.S. Department of Agriculture Forest Service.

Elm Disease Resistance Research Gets a Boost

Year: 2016

Great news for disease-tolerant American elm! A grant from The Manton Foundation has provided the Forest Service’s Northern Research Station with an opportunity to accelerate American elm research in collaboration with Nature Conservancy.

Expansion of the American Elm Restoration Project in New England in Collaboration With The Nature Conservancy

Year: 2010

The American elm in hardwood forests and riparian ecosystems has been greatly reduced or eliminated by Dutch elm disease (DED) and has not been replaced as the dominant overstory hardwood tree. NRS scientist James Slavicek, in collaboration with The Nature Conservancy (TNC), has recently established (June 2010) three sites for American elm restoration on TNC lands.

Last modified: Tuesday, March 26, 2019