Evaluation of race and copper tolerant strains of Xanthomonas axonopodis pv. vesicatoria, causal agent of bacterial leaf spot of bell pepper in Georgia

Abstract

Each year, Georgia pepper growers are confronted with the problem of bacterial leaf spot (BLS) caused by the bacterium Xanthomonas axonopodis pv. vesicatoria (XAV). The disease is devastating in hot, humid conditions and can cause millions of dollars in losses each year. Currently, management options include copper-based bactericides and growing pepper varieties with resistance to BLS. From 2007-2008, a survey was conducted to determine the frequency of copper (Cu) tolerance and distribution of BLS races in GA. Research was also conducted to evaluate two different Cu tolerance assays. Of 155 collected field strains, 89% were found to be Cu-tolerant on Cu-amended media. From 119 XAV strains, the majority were race 9 and 10, 36.1 and 50.4%, respectively. Strains grown in liquid Cu concentrations showed variable growth and demonstrated less growth than the control. No growth was observed at the highest concentration of Cu tested.