Four Common Setaria Species are Alternative Hosts for Clavibacter michiganensis subsp. nebraskensis , Causal Agent of Goss's Bacterial Wilt and Blight of Corn

Abstract

Goss's bacterial wilt and blight, caused by Clavibacter michiganensis subsp. nebraskensis (Cmn), has reemerged as an important disease of Zea mays (corn) in the U.S. Midwest. Results from a 2011 multistate survey indicated that Setaria spp. (foxtail) were often present in corn fields with a history of Cmn. The objective of this research was to determine if Setaria spp. that are common in the Midwest are susceptible to infection by Cmn. In the greenhouse, seedlings of four Setaria spp., including S. viridis (green foxtail), S. faberi (giant foxtail), S. verticillata (bristly foxtail), and S. pumila (yellow foxtail), and Zea mays (Golden Cross Bantam sweet corn, GCB) were inoculated with a suspension of 1.0 × 10 7 bacteria cells. The trial was arranged in a randomized complete block design and repeated once. Percent of symptomatic leaf area was visually estimated eight days after inoculation. S. faberi exhibited the highest levels of disease among the four Setaria spp., with disease incidence similar to what was observed on Z. mays. S. viridis was the next most susceptible. Symptoms were also observed on S. viridis, S. verticillata, and were lowest for S. pumila. Bacterial streaming was confirmed microscopically and Cmn was reisolated from the four Setaria species. Results indicate that these four Setaria spp. are susceptible to Cmn, thus serving as potential sources of inoculum. Accepted for publication 1 February 2014. Published 28 April 2014.Results from a 2011 multistate survey indicated that Setaria spp. (foxtail) were often present in corn fields with a history of Goss's bacterial wilt and blight, caused by Clavibacter michiganensis subsp. nebraskensis (Cmn). The objective of this research was to determine if Setaria spp. that are common in the Midwest are susceptible to infection by Cmn.