Plant Pathology and its Presence in Western Nebraska

Editor’s note: This is one of a series of articles about the people and programs that are part of the history of the University of Nebraska Panhandle Research and Extension Center at Scottsbluff. The Panhandle Center is celebrating its centennial in 2010.

By Robert M. Harveson
Extension Plant Pathologist
Panhandle REC, Scottsbluff

Early Studies

Although not officially recognized as a separate entity from botany until about 1920, plant pathology studies were being conducted as early as 1885, prior to the establishment of the Agricultural Experiment Station in 1887.

These studies were promoted by Charles Bessey, the first Dean of the College of Agriculture. Bessey was initially hired as the first station botanist, and conducted the first work in a small greenhouse on City Campus. He additionally included plant diseases in his botany course in 1884, although the subject had probably been previously taught by the Horticulture Department as cryptogamic botany - later known as mycology (the study of fungi). Between 1885 and 1905 almost a dozen reports, papers, and bulletins were produced pertaining to plant diseases by Bessey and his students.

Plant Pathology in Moves to Western Nebraska

Potato production became the first subject of plant disease studies in western Nebraska. In the summer of 1909 (prior to the establishment of the Scotts Bluff Experimental Substation in 1910) a potato disease lab was set up in Alliance with the help of special legislative funds to study storage diseases of potatoes. Work on tuber dry rot (caused by Fusarium trichothecioides) by Link served as his M.S. thesis in 1912, and also resulted in the publication of the first Research Bulletin (No. 1) of the Experiment Station. Link later published a comparative physiological study of the wilt fungus (caused by Fusarium oxysporum) with the dry-rot fungus in 1916 as Research Bulletin No. 9 (also his Ph.D. thesis).

During the early 1920s, both E. Mead Wilcox (Station Plant Pathologist) and Robert W. Goss (later Dean of the Graduate College) attempted to set up plant disease experiments at the Scotts Bluff Substation, but gave up after several years. The director of the substation at that time (James Holden) had no interest in research collaborations with East Campus staff members. It was stated that Wilcox was not able to conduct satisfactory work at the substation until 1935, with the arrival of Lionel Harris as superintendent.

In the mid-twenties, additional work was begun with the purpose of reversing severe yield reductions in alfalfa crops due to the combination of the bacterial wilt disease and winter injury, through the collaborations of UNL plant pathologist George Peltier, USDA, and the Agronomy Department. This resulted in the variety Ranger, which became the first winter hardy, wilt resistant variety ever developed. It subsequently became the leading variety grown in the U.S. through the 1960s.

In 1930, an experimental farm was established by the Experiment Station near Alliance (later known as the Northwestern Agricultural Lab) in cooperation with Box Butte County with the primary purpose of studying potatoes under dry land conditions. After unsuccessfully working with Holden at the Scotts Bluff Substation, Goss continued at the Alliance field lab working with soil-borne diseases such as scab and root rot (Rhizoctonia) and their relation with crop rotation, and some of the first studies with viruses.

Expansion of Plant Pathology in Western Nebraska

The arrival of Lionel Harris resulted in a change of philosophy for cooperation with the University of Nebraska, as he promoted maximum cooperation with East Campus staff members and Extension. Plant pathology has played a major role in both research and extension activities ever since. For the next 30 years, plant pathology personnel from East Campus were stationed at Scottsbluff during the summers to conduct field experiments and address disease problems more efficiently. Beginning in 1946, Max Schuster was assigned this task, and studied soil-borne and virus diseases of potatoes, bacterial diseases of dry beans, corn stalk rots, and sugar beet root diseases.

First Permanent Extension Plant Pathologist

As a result of a committee established in 1965 to evaluate current and future research and extension needs in western Nebraska, the No. 1 recommended priority for new specialist positions in the Panhandle Area was judged to be a plant pathologist. Thus Eric Kerr was hired in 1967 as the first full-time extension plant pathologist at the Panhandle REC. His appointment was changed to 50 percent extension and 50 percent research in 1980, as the position still exists to this day.

Kerr established effective nematocidal treatments against sugar beet nematodes, and provided the industry with guidelines for determining the threshold levels of nematode populations needed for economical nematocide treatments. He also studied nematode diseases of corn and the carry-over effects of nematocidal soil treatments in a corn-dry bean-sugar beet rotation.

He further contributed to selection of fungicides for sugar beet powdery mildew control with aerial applications and with Al Weiss (extension climatologist) developed a forecasting system for predicting optimal time periods for applying fungicides for Cercospora leaf spot control in sugar beets (which is still in use today). He additionally collaborated with Lincoln-based faculty in the biological control of Rhizoctonia root rot in sugar beets, mycorrhizal studies in wheat, and control of white mold, rust, and bacterial diseases of dry beans. His extension program is still recognized for his unselfish dedication to solving producer’s problems.

Changing of the Guard in Scottsbluff

Kerr retired in March 1998 and his position was filled in 1999 by Robert Harveson, who currently has responsibility for specialty crop diseases with an emphasis on sugar beets, dry beans, and sunflowers. He has determined that Aphanomyces root rot is a major component of the root disease complex in sugar beets (with rhizomania, Rhizoctonia root rot, and others) and is focusing on integrated methods of management, including biological, cultural, chemical, and predictive. He also is studying the re-appearance of the bacterial wilt disease of dry beans (first investigated by M. Schuster in the 1950s), and its ability to survive on other crops grown in rotation with dry beans.

He also recently identified the early stages of sunflower rust for the first time from naturally-occurring field infections in volunteers and wild species, and the implications of this for subsequent disease development in commercial sunflower crops. His extension program has focused on providing a disease diagnostic service for producers (more than 22,000 samples since 2000) that tests both soils and plant materials for the identification and incidence of multiple pathogens.

Typical wilt symptoms in dry edible bean, consisting of interveinal necrosis (death) surrounded by yellow borders. The inset photo shows the pink wilt pathogen variant growing in culture compared to the typical yellow, orange, and purple variants (inset).

These sugarbeets show multiple diseases from a single field found infecting roots simultaneously. Roots from left to right infected with 1) Aphanomyces and Rhzoctonia root rots; 2) Fusarium root rot/ yellows, and 3) rhizomania.