A History of Plant Pathology in Kentucky in the 20th Century

L. Henson (left) & R. Chapman

S. Diachun

H. Wheeler

W. Valleau

E. Johnson

Stokes & Litton

Plant pathology at the University of Kentucky began with the hiring of Dr. W. Valleau as Professor of Plant Pathology in the Department of Agronomy in 1919. Although he was not technically the first person with the title of plant pathologist at U.K. (that honor belongs to Miss Mable Roe, who was employed by the Agronomy Department for one year in 1918 as an Assistant Plant Pathologist), it was Valleau who initiated plant pathology as a discipline here, with functions in both research and teaching.   Dr. Valleau earned his Ph.D. degree from the University of Minnesota, one of the first Plant Pathology Departments in the United States.   In 1923, E. Johnson, who later also received his Ph.D. degree from the University of Minnesota, joined Valleau at Kentucky.   In 1931, L. Henson, and in 1937, Dr. S. Diachun (Ph.D., Illinois) also joined the plant pathology staff. Henson held a joint appointment in forage crop agronomy.   It is interesting to note the relative frequency of hires that had not yet earned their Ph.D. degrees: at the time the practice was quite normal, especially since there were very few formal Departments of Plant Pathology in the country, and thus few people with advanced training in the area.

It was typical in the first half of the 20 th century for plant pathologists to be "generalists", responding to all kinds of disease problems as they arose.   The pathology group at Kentucky was no exception, and they conducted research on the etiology and control of everything from bacterial diseases of peach to viral diseases of clover.   However, the overriding theme of their work was in the area of tobacco pathology.   Tobacco was the most important cash crop for the region, and diseases were a major limiting factor.   Furthermore, little had been done to address disease problems of tobacco and so the group at Kentucky became pioneers in this area, conducting many studies from the 1920s through the 1950s of various viral, fungal, oomycete, and bacterial diseases.   The tobacco pathology program at Kentucky included a component focused on breeding resistant varieties of the types of tobacco commonly grown here.   This program was very successful: one important accomplishment during this early era was the introduction of the "N" gene for resistance to tobacco mosaic virus into burley and dark tobaccos. Another was the breeding of varieties of tobacco with tolerance to the black root rot fungus, Thielaviopsis basicola .

Dr. R. Chapman (Ph.D., Illinois), and Dr. G. Stokes (Ph.D., Wisconsin) joined the staff between 1950 and 1953.   With Valleau, Johnson, Henson, and Diachun, they made up the plant pathology group within the Department of Agronomy.   In 1963, an independent Department of Plant Pathology was established, with Dr. Chapman as its first chair.   Members of the new department were Johnson, Henson, Diachun, Stokes, Dr. R. Hampton (Ph.D., Wisconsin, hired in 1960), Dr. R. Reinert (Ph.D., Wisconsin, hired in 1962), C. Litton (USDA, transferred in 1962 to replace Dr. Valleau in the tobacco breeding program), and Dr. J. Oswald (Ph.D., California), who was appointed President of the University of Kentucky in 1963, but held an academic appointment in Plant Pathology. Dr. Valleau retired in 1961 after a long and illustrious career.

S. Diachun

M. Siegel

J. Shaw

J. Kuc Hartmann & Stuckey

S. Ghabrial

With the appointment of Dr. Hampton in 1960, plant pathology at U.K. initiated a focus on disease physiology, which would become a unifying theme in the department.   In 1964, Dr. J. Hendrix (Ph.D.,North Carolina State) was hired and began his studies on the physiology of oomycetes, while in 1966 Dr. M. Siegel (Ph.D., University of Maryland) joined the faculty and started work to investigate the modes of action of various fungicides. The disease physiology program was given a major boost in 1967 when Dr. H. Wheeler (Ph.D., Louisiana State University) was attracted to the department from Louisiana State University. Dr. Wheeler already had an international reputation for his pioneering work on fungal toxins.   In the same year, Dr. T. Pirone (Ph.D., University of Wisconsin) also transferred from Louisiana and began to develop his program in the area of virus-vector interactions. With the addition of Dr. J. Shaw (Ph.D., University of Wisconsin) and his established program on viral infection processes in 1968, the nucleus of the department's world-renowned research program in molecular plant virology was formed. The year 1968 also saw the appointment of the department's second chairman, Dr. S. Diachun. During the 1960s, Dr. Johnson retired, and Drs. Stokes, Reinert, and Hampton left the department for administrative duties (Stokes) or other universities (Reinert, Hampton).

T. Pirone

L. Shain

R. Shepherd

During the 1970s, the focus of departmental research was in three main areas (disease physiology, virology, and soil microbiology), all unified by an emphasis on the use of biochemical and physiological methods for analysis.   Several important additions to the faculty were made during the 1970s in the area of disease physiology, including Dr. L. Shain (Ph.D., North Carolina State) in 1972, who focused his research on the physiology of tree diseases, and Dr. J. Kuc (Ph.D., Purdue University), who was attracted from Purdue in 1974 and who brought with him his established program on fungal elicitors and induced resistance. In 1979, Dr. D. Smith (Ph.D., Cornell University) was appointed and added his program on phytoalexins to the disease physiology group at Kentucky. Dr. S. Ghabrial (Ph.D., Louisiana State University) joined the virology group in 1972 (initially in the tobacco and health program, with full responsibilities in virology in 1975). Over the years, Dr. Ghabrial built an internationally known program on mycoviruses.   In 1978, the department's third chairman, Dr. T. Pirone, was appointed to replace Dr. Diachun, who retired but continued to be active in the department as an Emeritus Professor.

The 1970s also saw a dramatic expansion of the department's Extension group.   The department's first Extension pathologist, Dr. A. Williams (Ph.D., North Carolina State), was appointed in 1968.   At first, Dr. Williams had sole responsibility for all crops with the exception of tobacco, which was shared with Dr. Smiley in Agronomy.   This changed when Dr. J. Hartman (Ph.D., University of Wisconsin) was hired in 1971, followed by Dr. R. Stuckey (Ph.D., Michigan State University) in 1975 (to replace Williams when he assumed the chairmanship of Horticulture and Landscape Architecture).   Dr. W. Nesmith (Ph.D., North Carolina State) joined the group in 1979.   In 1982, an Extension position was created at Princeton and was filled by Dr. W. Wilcox (Ph.D., University of California Davis) until 1984, when Dr. D. Hershman (Ph.D., Rutgers University) was hired.   In 1989, Dr. P. Vincelli (Ph.D., Cornell University) was hired to replace Dr. Stuckey. The latest addition to the extension group is Dr. K. Seebold (Ph.D., University of Florida), hired in Spring of 2005 to replace Dr. Nesmith.  The Extension group has worked on many disease problems, and has dealt effectively with major challenges as they arose. The Extension group has made it possible for the other faculty in the department to focus on more basic studies of the genetics, biochemistry, and physiology of disease. They have taken on major responsibilities for applied and developmental research, in addition to their Extension duties, and they have also engaged in productive collaborations with their non-Extension colleagues, and have suggested areas of emphasis for their research. Thus, Plant Pathology at Kentucky has had a long and quite unique tradition of close collaboration between applied and basic research that has served the Commonwealth well.

The department moved into the area of fungal molecular genetics with the hiring of Dr. C. Schardl (Ph.D., University of California, Davis) in 1984.   Dr. Schardl worked productively with several members of the fungal disease physiology group before settling down to collaborate with Dr. Siegel, who had been engaged in studies of endophytic fungi of forage grasses that produced toxins responsible for illnesses in livestock. In Dr. Schardl's hands, this program has become one of the most prominent and important in the department. In 1985, the virology group received a tremendous boost when Dr. R. Shepherd (Ph.D., University of Wisconsin) moved his program from California to Kentucky. Dr. Shepherd focused on the development of DNA viruses as gene vectors for plants. He was elected a member of the National Academy of Sciences in 1988. In 1986, the department's fourth and present chairman, Dr. D. Smith, was appointed. During the 1980s, Drs. Chapman and Wheeler retired.

During the 1990s, the make-up of the department changed dramatically. Drs. Kuc, Shain, Shepherd, Pirone, Shaw, and Siegel all retired, leaving major gaps to be filled! Their successors included Drs. L. Vaillancourt (Ph.D., Purdue) and M. Farman (Ph.D. University of East Anglia), in molecular fungal genetics, Drs. P. Nagy (Ph.D., Keszthely University) and M. Goodin (Ph.D., Pennsylvania State University), in molecular virology, and Dr. P. Kachroo (Ph.D., University of Baroda), who studies mechanisms of disease resistance in the model plant Arabidopsis thaliana . The department as it now exists has an excellent balance between junior and senior faculty members, and between research and Extension. In the tradition of our predecessors, we continue to be committed to producing high-quality, cutting-edge research on pathogen biochemistry and genetics as well as on the physiology and molecular mechanisms of disease interactions. We are also dedicated to serving the Commonwealth of Kentucky under the leadership of our experienced Extension team. The next century will hold many challenges, but we will be prepared because of the firm foundation that has been provided by the dedicated people who built this department from its beginnings.  

Some of the information contained in this history was taken from the article "Fifty Years of Plant Pathology in Kentucky", by W.D. Valleau (Transactions of the Kentucky Academy of Science, Volume 25, Numbers 1-2: 27-47

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