Robert M. Harveson, Extension Plant Pathologist University of Nebraska, Panhandle REC, Scottsbluff
Author’s note: This article focuses on landmark events in Nebraska agricultural history. It is a simple list of novel reports and discoveries, or significant achievements in plant pathology made between 1884 and 2015. They were made either in Nebraska or by University of Nebraska personnel (current or former faculty, post doctorals, staff, and students). Unless otherwise indicated, all named persons are Department of Plant Pathology members.
1884 - Charles Bessey – although not officially recognized as a separate entity from botany until about 1920, plant pathology actually began in 1884-1885 with the arrival of Charles Bessey. This was a full two years prior to the establishment of the Agricultural Experiment Station in 1887. Bessey was initially hired as the first station botanist, and also served as the first Dean of the College of Agriculture. He strongly promoted plant pathological studies and 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 – the first plant pathology publications in Nebraska.
1890 – Roscoe Pound – student of Bessey’s (B.S. and M.A.) and W. J. Webber independently reported violet root rot from alfalfa (caused by Rhizoctonia crocorum) from two distinct locations in Nebraska. This proved to be the first Rhizoctonia disease reported in the U.S.
Late 1890s – George Hedgcock – another student of Bessey’s (B.S. and M.A.) that reported observations on severe outbreaks occurring prior to 1888 from garden beets in Nebraska that today are assumed to be the leafhopper-transmitted virus disease, beet curly top.
1904 – Haven Metcalf – obtained the Ph.D. from the agricultural botany department with a thesis entitled “A soft rot of sugar beet”. The pathogen was a new bacterium identified as Bacterium teutlium, and included the first introduction of the new bacteriological techniques into the department.
1912 -1914 – Venus W. Pool (former graduate student) – discovers the sugar beet seedling rust pathogen (Puccinia subnitens) in Colorado on sugar beets for the first time, working out its unique life cycle and several alternate hosts. 2010 – Robert Harveson - reported a widespread epidemic of this same rare disease throughout the Nebraska panhandle, making it the first documentation of the disease from a field infection in a century.
1922 – George Peltier – generally is credited with the discovery and first recognition of wheat steak mosaic virus from UNL’s research plots in Lancaster County. He mechanically transmitted the pathogen to healthy wheat and corn plants using plant sap from symptomatic wheat plants.
Mid-1920’s – George Peltier – also noted the appearance of bacterial wilt of alfalfa, caused by Clavibacter michiganensis subsp. insidiosum, from Nebraska river valleys simultaneously with similar reports from Kansas, Wisconsin, and Illinois. His work on this disease with the USDA’s H. M. Tysdal resulted in the winter-hardy, wilt-resistant cultivar, ‘Ranger’, which was the first alfalfa cultivar developed utilizing a gene derived from a foreign source for disease resistance with corresponding desirable agronomic traits.
1949 – Max Schuster – identified bacterial wilt of dry beans, caused by Curtobacterium flaccumfaciens pv. flaccumfaciens from Nebraska. The original report from South Dakota described bacterial isolates that were yellow-pigmented. Schuster then identified another pathogen color variant (orange) in 1957 and a purple color variant in 1967 with Anne Vidaver. Robert Harveson discovers a fourth color variant (pink) of the pathogen in 2008. All new color variants were found originally in Scotts Bluff County.
1949 – Max Schuster - first identified the false root-knot nematode (Nacobbus aberrans) from sugar beets near Mitchell NE. He later found this same pathogen infecting prickly pear cacti from uncultivated range lands in Scottsbluff and Sioux Counties, suggesting it was a nematode native to western Nebraska.
1954 – William Allington, Robert Staples (UNL entomology department), and Charlie Fenster (UNL agronomy department): Studied the spread and degree of damage caused by the wheat streak mosaic pathogen. These studies established the epidemiology of the disease after a historically severe hail storm moved through Kimball and Cheyenne counties the previous year.
1960 – Mike Boosalis: Found a sterile basidiomycetious fungus (later identified as Laetisaria arvalis) from Rhizoctonia root rot-infected sugar beets from Scotts Bluff County. This organism becomes one of the more widespread and successfully utilized biocontrol agents for managing soilborne pathogens.
1966 – Myron Brakke: First identified the vector (Polymyxa graminis) for wheat soilborne mosaic virus from Nebraska.
1969 – David Wysong, Anne Vidaver, and Max Schuster: Discovered and characterized a new bacterial disease of corn (Goss’ wilt, caused by Clavibacter michiganensis subsp. nebraskensis) from central Nebraska near Lexington. This disease essentially (not completely, but below levels of concern) disappeared in the early 1980’s, but reappeared again throughout the central high plains in the mid-2000s, before spreading across the corn belt and into Canada.
1970s – Anne Vidaver and James Van Etten: Identified and characterized a novel bacteriophage (infecting Pseudomonas phaseolicola) that had a dsRNA genome and an external lipid membrane. For many years it was the only virus known with these properties.
1972 – Charlie Fenster (UNL agronomy department), Mike Boosalis, and John Weihing: Conducted research for more than 20 years on the stress related root and crown rot disease of wheat. The disease was found to be reduced by varying planting dates for different regions based on elevation of fields. Previously this disease was a major production constraint for many years in western Nebraska, and recommendations are still being used today based on this concept.
1974 – Myron Brakke: Was the first person from UNL elected into the National Academy of Sciences
Mid-1970s – Ben Doupnik and Mike Boosalis discovered the effects on corn and sorghum stalk rots due to the process of “eco-fallowing”. This was reduced tillage cropping system initiated in the early 1960s by Gail Wicks and Darryl Smika (UNL agronomy department) aimed at chemically controlling weeds and conserving soil moisture with a minimum of soil and crop residue disturbance. Doupnik and Boosalis found that planting corn or sorghum into untilled wheat residue significantly increased yields and reduced stalk rot disease, presumably due to lower soil temperatures, higher soil moisture, and better weed control.
1976-1979 – Randall Carlson (graduate student) and Anne Vidaver – discovered and characterized a new bacterial disease of wheat (bacterial mosaic, caused by Clavibacter michiganensis subsp. tesselarius). This disease was found suddenly and widespread from Scottsbluff County in the west to Crawford County in western Iowa. Similar to Goss’ wilt, it essentially disappeared by the early 1980’s, but unlike Goss’ wilt has not reappeared in commercial fields since.
1980 to present – James Van Etten and Russ Meints (UNL biology department chair) – discovered and characterized a number of large, dsDNA viruses that infected certain species of fresh water green algae.
1982 – William Langenberg and Eric Kerr – discovered the vector (Polymyxa betae) for beet necrotic yellow vein virus, causal agent of rhizomania, in five of six sugar beet fields surveyed from Scotts Bluff County. This was the first time this organism was found directly infecting sugar beet roots in the western hemisphere, but was determined to be aviruliferous. The virus disease was not identified from Nebraska for another decade.
1984 – Anne Vidaver - was appointed as the first female in the United States to head a Department of Plant Pathology, and possibly the first female to head a traditional agriculture department.
1986 - Anne Vidaver became the second woman to be president of the American Phytopathological Society.
1984 – Joseph Daly - (a former member of the Department of Plant Pathology) was elected into the National Academy of Sciences.
1995 - Paula Flynn (graduate student) and Anne Vidaver discovered and characterized a new bacterial disease of milkweed (Ascelpias sp.), a potential row crop in Nebraska.
1997-1999 – Robert Harveson - discovered a group of related mycoparasites in association with several distinct Fusarium wilt diseases, characterized their relationships with different form species of F. oxysporum and demonstrated for the first time the ability of these fungi to serve as potential biological control agents for Fusarium wilt of watermelon.
2000-2002 – Anne Vidaver - served as the Chief Scientist for the USDA NRI competitive grants program.
2003 – James Van Etten - elected into the National Academy of Sciences.
2013 – Robert Harveson and Melvin Bolton (USDA colleague) - identified the dry rot canker disease of sugar beets to be caused by binucleate species of Rhizoctonia (anastomosis group – AG F) distinct from and previously assumed to be caused by R. solani.
2013-2015 – Tamra Jackson-Ziems and Kevin Korus – discovered a new and problematic bacterial disease of corn. Its formal identity is uncertain at this point, but does appear to be widespread throughout much of Nebraska corn production.
2014 – Robert Harveson – identified and documented the parasitic plant Orobanche ludoviciana infecting sunflower plants in Kimball County. It was the first report for any Orobanche species found parasitizing commercial sunflowers in the western hemisphere.
2015 – Robert Harveson and Kimberly Webb (USDA colleague) –Identified an unknown, sterile fungus, previously isolated from infected sugar beet seedlings from Box Butte County. The fungus was identified as Rhizoctonia zeae and was characterized and demonstrated to be a potentially effective biological control agent for sugar beet root rot pathogens, particularly R. solani.
2016 - Myron Brakke, James Van Etten and Anne Vidaver became the only trio of faculty (in different years) given the Award of Distinction by the American Phtyopathological Society.