Bioherbicidal potential of Xanthomonas campestris for controlling Conyza canadensis

The effects of environmental parameters on bioherbicidal activity of the bacterium Xanthomonas campestris, against glyphosate-resistant and – susceptible Conyza canadensis (horseweed), were studied under greenhouse conditions. Rosette leaf-stage plants were more susceptible than older plants, and increasing inoculum from 10⁵ to 10⁹ cells/mL caused significantly greater plant mortality and biomass reduction of plants in both the rosette and bolting growth stages. A dew period at 25°C was required to cause an 80% and 60% mortality of plants in the rosette and bolting growth stages, respectively. Results indicate that X. campestris can infect and kill horseweed, demonstrating its bioherbicidal potential.