The bacterial pathogen Xanthomonas vasicola pv. vasculorum was first reported in the United States causing bacterial leaf streak on Nebraska corn (Zea mays) in 2016. The bacterium is also known to cause disease in sugarcane, grain sorghum, broom bamboo, and various palm species. The objective of this study was to identify alternative hosts for X. vasicola pv. vasculorum among plants commonly found in corn growing areas of the United States. In repeated greenhouse experiments, 53 species of plants found in the United States that had not been tested previously for susceptibility to X. vasicola pv. vasculorum were inoculated with the pathogen and monitored for symptom development. Eleven species in the family Poaceae exhibited symptoms: oat (Avena sativa), rice (Oryza sativa), orchardgrass (Dactylis glomerata), indiangrass (Sorghastrum nutans), big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), timothy (Phleum pratense), sand bluestem (Andropogon hallii), green foxtail (Setaria viridis), bristly foxtail (Setaria verticillata), and johnsongrass (Sorghum halepense). Yellow nutsedge (Cyperus esculentus) in the Cyperaceae also was a symptomatic host. In addition, endophytic colonization by X. vasicola pv. vasculorum was found in three asymptomatic alternative hosts: downy brome (Bromus tectorum), tall fescue (Festuca arundinacea), and western wheatgrass (Pascopyum smithii). Experiments were also conducted in the field to determine the potential for alternative hosts to become infected by natural inoculum. Symptoms developed only in big bluestem and bristly foxtail in field experiments. These results suggest that infection of alternative hosts by X. vasicola pv. vasculorum can occur, but infection rates might be limited by environmental conditions.
Keywords: bacteriology; ecology and epidemiology.