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Kenneth B. Johnson

Kenneth B. Johnson, John N. Pinkerton, and Jeffrey K. Stone are recognized for their outstanding work on the eastern filbert blight disease of European hazelnut (Corylus avellana). Since the disease was first reported in the Willamette Valley of Oregon in 1986, their work has described the etiology, epidemiology, and management strategies for control of the disease. They have described factors that are required for release of ascospores of the causal agent, Anisogramma anomala, and they have identified the weather conditions that produce the greatest risk for disease spread. From this data, they developed epidemiological models that describe the likelihood of release of ascospores during individual rain events as affected by rain duration and time of the year. In addition, the annual pattern of ascospore maturation and the relationship of cumulative annual precipitation to cumulative spore release have been used to develop a model that predicts the relative availability of inoculum during the period when hazelnuts are susceptible to infection.

Their research also has addressed the processes of regional disease spread. Using spore traps mounted on towers and trap trees, they concluded that ascospores are discharged actively and that the spores move rapidly up and away from orchards during periods of heavy rain. They used this data as well as historical weather records to explain the current distribution of eastern filbert blight and to estimate the likelihood of the disease spreading into noninfected areas. This information, along with survey data, was used to further characterize the epidemic and develop regulatory programs to contain the disease.

Another aspect of their research involved characterizing the infection biology of A. anomala and host response to infection. They determined that the infection site was immature shoots formed after bud break, rather than dormant buds damaged by Eriophyid mites as previously reported. In histological studies, they described the adhesion and germination of ascospores on hazelnut shoots and the direct penetration of the germinated hyphae. They have documented the host response at the infection site, as well as the response of a large collection of Corylus germ plasm to A. anomala in field screening projects. They also have conducted experiments to ascertain the effects of temperature and moisture on the survival, germination, and infectivity of ascospores of A. anomala and developed an axenic culture method for A. anomala that furthered the understanding of the biotrophic nature of this pathogen. This latter research also demonstrated the involvement of autohibitors to ascospore germination.

Their collaboration has resulted in a thorough understanding of the biology of A. anomala and the epidemiology of eastern filbert blight. With this as a basis, they developed a disease management program that combined information on cultivar susceptibility, disease sanitation, and properly timed fungicide applications. Growers have been able to maintain productivity of infected trees in orchards with this program.

Their contributions to the understanding and management of the eastern filbert blight have been original, creative, multifaceted, and well documented, as evidenced by the publication of 12 scientific articles in Phytopathology, Plant Disease, and Mycologia since 1992. Drs. Pinkerton, Stone, and Johnson were presented the Oldfield/Jackman Team Research Award for their collaborative contributions to the understanding of eastern filbert blight by the College of Agriculture at Oregon State University.

Kenneth B. Johnson was born in Minneapolis, MN. He obtained his B.S. degree in plant health technology in 1979 from the University of Minnesota and his M.S. degree in plant pathology from Oregon State University in 1982. He completed his Ph.D. degree in plant pathology in 1986 at the University of Minnesota and continued as a postdoctoral associate and lecturer until 1988. He then joined the faculty of the Department of Botany and Plant Pathology at Oregon State University, where he is an associate professor. Dr. Johnson has distinguished himself through outstanding, pioneering research on potato and deciduous tree fruit and nut crop diseases. His research focuses on the areas of quantitative epidemiology, integrated control, and application of epidemiological principles for enhancing biocontrol. He teaches graduate courses on plant pathology and disease management. Dr. Johnson has served APS as a member and chair of the Plant Disease Losses and Epidemiology committees, as a member of the Ad Hoc Committee for Plant Pathology 2000, and as associate and senior editor of Phytopathology. He also has been active in the IPPC Epidemiology Committee. In 1996, APS honored him with the Ciba-Geigy Award for his significant contributions to the advancement of knowledge of plant diseases and their control.

John N. Pinkerton was born in Englewood, NJ. He received a B.S. degree in zoology from Oregon State University in 1968. After serving as an extension fisheries specialist with the Peace Corps in Nepal, he returned to Oregon State University to pursue a Ph.D. degree in plant pathology. While in graduate school, he was the extension nematologist and ran the plant clinic’s nematology laboratory. In 1983, he accepted a research associate position in nematology with Washington State University at the Irrigated Agriculture Research and Extension Center, Prosser. Between 1986 and 1988, he worked for the Oregon Department of Agriculture as a plant pathologist. In 1988, he accepted a position with the USDA-ARS Horticultural Crops Research Laboratory in Corvallis, OR, to work on the epidemiology and management of eastern filbert blight. In 1996, his responsibilities at the USDA changed to the epidemiology and management of phytonematodes and soilborne plant pathogens in small fruit and ornamental nursery production. Dr. Pinkerton is a member of APS and has served on the Nematology Committee. He also is a member of the Society of Nematologists and the Organization of Nematologists of Tropical America.

Jeffrey K. Stone was born in East Liverpool, OH. He received a B.A. degree in biology in 1976 from Antioch College, Yellow Springs, OH. He completed a Ph.D. degree in biology and mycology at the University of Oregon in 1986. His doctoral research dealt with the ecology, taxonomy, and physiology of Rhabdocline parkerii, an asymptomatic foliar endophyte of Douglas fir. From 1987 to 1990, he served as a research associate at the Department of Botany and Plant Pathology, Oregon State University in Corvallis. It was at this time that he was actively involved in studying the pathology of A. anomala on European hazelnut. In 1993, he accepted a position as assistant professor (senior researcher). His research interests continue to be the ecology, distribution, and biodiversity of fungal parasites of plants in natural systems, and endophytes. He has also been involved with the pathology, ecology, and taxonomy of foliar and stem fungi of woody hosts, and the systematics and evolutionary biology of inoperculate discomycetes. He teaches courses in fungal plant pathogens (mycology), biology of conidial fungi, and forest pathology at Oregon State University. Dr. Stone is a member of APS, the Mycological Society of America, the British Mycological Society, and the International Symbiosis Society. He is currently an associate editor for Mycologia and serves as the chair of the MSA Endowment Committee. In addition, he has served as a MSA councilor of ecology/pathology.