Recent Publications from Dr Nutter and Dr Robertson

April 12, 2016
News

The Evolution of a Process for Selecting and Prioritizing Plant Diseases for Recovery Plans

N. McRoberts, Department of Plant Pathology, University of California, Davis; C. S. Thomas, Department of Plant Pathology, University of California, Davis; J. K. Brown, School of Plant Sciences, University of Arizona, Tucson; F. W. Nutter, Department of Plant Pathology, Iowa State University, Ames; J. P. Stack, Department of Plant Pathology, Kansas State University, Manhattan; and R. D. Martyn, Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN

Abstract:

One element of the cost of dealing with invasive species in the United States is the recovery from the arrival of exotic plant pathogens. We review the development of a process used to prioritize plant diseases for the federally mandated United State Department of Agriculture National Plant Disease Recovery System. A team of university, government, and industry scientists worked together over a 10-year period to develop a science-based objective approach to the challenge of effectively preparing for recovery plans from introduced pathogens, when the timing of the introduction of any single disease is unknown. Over time, the process transitioned from ad hoc, in which recovery plans were written when the relevant experts were able to do so, to a formally organized group-prioritization effort from which emerged the concept of generic recovery plan templates for groups of pathogens and diseases that have similar biological characteristics, and therefore, similar management approaches. Key characteristics for each template were determined through a multivariate analysis for 14 plant diseases for which a recovery plan already existed. The process was validated by a larger group of 15 plant pathologists, for which results were compared with those scored by 14 subject matter experts.

Source: APS 


Dissemination of Goss’s Wilt of Corn and Epiphytic Clavibacter michiganensis subsp. nebraskensis from Inoculum Point Sources

Sharon Eggenberger, Department of Plant Pathology and Microbiology, Iowa State University, Ames 50014; Mercedes M. Diaz-Arias, Monsanto Company, St. Louis 63006; Andrew V. Gougherty, Appalachian Laboratory, University of Maryland Center for Environmental Science, Frostburg, 21532; Forrest W. Nutter, Jr., Department of Plant Pathology and Microbiology, Iowa State University; Jeff Sernett, Fifth author: Monsanto Company, Huxley, IA 50124; and Alison E. Robertson, Department of Plant Pathology and Microbiology, Iowa State University

Abstract:

Goss’s wilt of corn, caused by Clavibacter michiganensis subsp. nebraskensis, has reemerged since 2006 as an economically important disease of corn in in the Midwestern United States. In 2012 and 2013, field plot studies were conducted with a pathogenic, rifampicin-resistant C. michiganensis subsp. nebraskensis isolate and a Goss’s wilt-susceptible corn hybrid to monitor epiphytic C. michiganensis subsp. nebraskensis population densities and the temporal and spatial spread of Goss’s wilt incidence originating from inoculum point sources. The randomized complete block trial included three treatments: noninoculated control, inoculum point sources established by wound inoculation, and inoculum point sources consisting of C. michiganensis subsp. nebraskensis-infested corn residue. Epiphytic C. michiganensis subsp. nebraskensis was detected on asymptomatic corn leaves collected up to 2.5 m away from inoculum sources at 15 days after inoculation in both years. The percentage of asymptomatic leaf samples on which epiphytic C. michiganensis subsp. nebraskensis was detected increased until mid-August in both years, and reached 90, 55, and 35% in wound-, residue-, and noninoculated plots, respectively, in 2012; and 50, 11, and 2%, respectively, in 2013. Although both growing seasons were drier than normal, Goss’s wilt incidence increased over time and space from all C. michiganensis subsp. nebraskensis point sources. Plots infested with C. michiganensis subsp. nebraskensis residue had final Goss’s wilt incidence of 7.5 and 1.8% in 2012 and 2013, respectively; plots with a wound-inoculated source had final Goss’s wilt incidence of 16.6 and 14.0% in 2012 and 2013, respectively. Our findings suggest that relatively recent outbreaks of Goss’s wilt in new regions of the United States may be the result of a gradual, nondetected buildup of C. michiganensis subsp. nebraskensis inoculum in fields.

Source: APS

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