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SPECIAL SESSION: Plant Pathologists of the Future: Showcasing Graduate Student Presentation Winners from APS Division Meetings

Alternative hosts of Xanthomonas vasicola pv. vasculorum, causal agent of bacterial leaf streak of corn
Terra Hartman - University of Nebraska-Lincoln. Brad Tharnish- University of Nebraska-Lincoln, Tamra Jackson-Ziems- University of Nebraska, Jim Harbour- University of Nebraska-Lincoln

The bacterial leaf streak pathogen Xanthomonas vasicola pv. vasculorum was reported on Nebraska corn in 2016, the first report in the United States. It is also the causal agent of gumming disease of sugarcane, and capable of infecting several other plant species, including Sorghum bicolor and some tropical plants. The diverse host range indicates the potential for this bacterium to infect plants associated with cornfields in the United States. To test this hypothesis, five replicates of various plants found in Nebraska, including crops, turf and ornamental grasses, prairie grasses, and weeds were spray inoculated in a greenhouse with a 108 CFU/mL aqueous suspension of X. vasicola pv. vasculorum. Twelve symptomatic alternative hosts included oat (Avena sativa), rice (Oryza sativa), orchardgrass (Dactylis glomerata), indiangrass (Sorghastrum mutans), big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), timothy (Phleum pretense), sand bluestem (Andropogon hallii), johnsongrass (Sorghum halepense), green foxtail (Setaria viridis), bristly foxtail (Setaria verticillata), and yellow nutsedge (Cyperus esculentus). Asymptomatic alternative hosts included downy brome (Bromus tectorum), tall fescue (Festuca arundinacea), and western wheatgrass (Pascopyum smithii). To test the likelihood of infection of susceptible species in the field, asymptomatic alternative hosts were transplanted to a field naturally infested with X. vasicola pv. vasculorum. From infection by natural inoculum, big bluestem and bristly foxtail developed symptoms.