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Wayne Sinclair

Wayne A. Sinclair

Professor Emeritus

(607) 272-6165


  • 1962, Ph. D. Cornell University
  • 1958, B.S. University of New Hampshire

Professional Experience

  • 2000-present, Professor Emeritus, Department of Plant Pathology, 2000-present
  • 1962-1975, Professor, 1975-1999; Asst. Prof., Assoc. Prof., Cornell
  • 1970, Visiting Forest Pathologist, Weyerhaeuser Company, Centralia, WA

Research and Service Interests

Pathology of trees and shrubs. Biology and management of phytoplasmal disease of trees, mainly ash yellows and elm yellows. My laboratory closed in 2000. Research on ash yellows during the 1990s included studies of epidemiology, host variation in response to phytoplasmal infection, variation in pathogen aggressiveness, rootstock-scion interactions on symptom expression; and classification, diagnosis, molecular variability, and insect carriers of ash yellows phytoplasmas. Research on elm yellows included molecular differentiation of elm-inhabiting members of the elm yellows phytoplasma group and evaluation of elm cultivars for reaction to the pathogen.

I respond to inquires and requests from arborists, horticulturists, and the public, and prepare reference materials used by those concerned with tree health.

Courses Taught

  • 1994-1999, Basic Plant Pathology, (preparation for graduate study in plant pathology)
  • 1980-1993, Introductory Plant Pathology
  • 1963-1980, Pathology of Trees & Shrubs

Honors & Awards

  • 2000 Gold Medal of Horticulture Award, New York State Nursery/Landscape Association
  • 2000 Edgerton Career Teaching Award, Cornell University, College of Agriculture & Life Sciences
  • 1994 Award of Merit, American Phytopathological Society, Northeastern Division
  • 1993 Authors Citation, International Society of Arboriculture
  • 1992 Fellow, American Phytopathological Society
  • 1987 Best New PSP Book in Life Sciences (Diseases of Trees and Shrubs), Professional and Scholarly Publishing Division, Association of American Publishers
  • 1987 Award of Merit, New York State Arborists Association I.S.A. Chapter

Other Professional Activities

  • 1982-85 Editor-in-Chief, Plant Disease, 1988-91; Senior Editor
  • 1988-91 APS Council
  • 1980-82 American Phytopathological Society Northeastern Division, officer sequence
  • 1973-83, 1992-94 Editorial Board, Forest Science
  • 1972-76 Northeastern Forest Pest Council, Chairman
  • International Society of Arboriculture
  • International Organization for Mycoplasmology




  • Sinclair, W. A. and Lyon, H. H. 2005. Diseases of Trees and Shrubs, 2nd ed. Cornell University Press, Ithaca, NY. 660 pp.

Chapters & reviews - 10 years

  • Sinclair, W. A. 2000. Phytoplasmal diseases and tree declines. Pages 15-24 in: Proceedings Mundulla Yellows National Conference, Adelaide, Australia, 22-23 June 2000. South Australian Society of Arboriculture and Australian Institute of Horticulture.
  • Sinclair, W. A. 2000. Elm yellows in North America. Pages 121-126 in: The Elms: Breeding, Conservation, and Disease Management. C. P. Dunn, ed. Kluwer Academic, Norwell, Mass.
  • Davis, R. E., and Sinclair, W. A. 1998. Phytoplasma identity and disease etiology. Phytopathology 88:1372-1376.
  • Sinclair, W. A., Griffiths, H. M., and Davis, R. E. 1996. Ash yellows and lilac witches'-broom: phytoplasmal diseases of concern in forestry and horticulture. Plant Dis. 80:468-475.

Research articles - 10 years

  • Sinclair, W. A., and Griffiths, H. M. 2000. Variation in aggressiveness of strains of ash yellows phytoplasmas. Plant Dis. 84:282-288.
  • Sinclair, W. A., Gleason, M. L., Griffiths, H. M., Iles, J. K., Zriba, N., Charlson, D. V., Batzer, J. C., and Whitlow, T. H. 2000. Responses of 11 Fraxinus cultivars to strains of ash yellows phytoplasmas that vary in aggressiveness. Plant Dis. 84:725-780.
  • Hill, G. T., and Sinclair, W. A. 2000. Taxa of leafhoppers carrying phytoplasmas on sites of ash yellows occurrence in New York State. Plant Dis. 84:134-138.
  • Griffiths, H. M., Sinclair, W. A., Smart, C. M., and Davis, R. E. 1999. The phytoplasma associated with ash yellows and lilac witches'-broom: `Candidatus Phytoplasma fraxini.' Int. J. Syst. Bacteriol. 49:1605-1614.
  • Griffiths, H. M., Sinclair, W. A., Boudon-Padieu, E., Daire, X., Lee, I.-M., Sfalanga, A., and Bertaccini, A. 1999. Phytoplasmas associated with elm yellows: molecular variability and differentiation from related organisms. Plant Dis. 83:1101-1104.
  • Mahoney, E. M., Milgroom, M. G., Sinclair, W. A. and Houston, D. R. 1999. Origin, genetic diversity, and population structure of Nectria coccinea var. faginata in North America. Mycologia 91:583-592.