Microwave Radiation as an Alternative Control for Seed-borne Diseases in Dry Bean

Abstract

Controlling the seed-borne pathogens Xanthomonas axonopodis pv. phaseoli, Pseudomonas syringae pv. phaseolicola, and Colletotrichum lindemuthianum is difficult in Canadian dry bean production. Laboratory and field studies conducted in 2012-2013 evaluated microwave radiation as an alternative control for these pathogens. In the laboratory, seed germination and vigour decreased by <10% and 25%, respectively, between 40-60 s of microwave exposure. Microwave radiation of seed infected with C. lindemuthianum resulted in a 0.10-0.14-% s-1 decrease in disease incidence, but no similar response was observed with bacterial diseases. Field studies evaluated the effect of microwave radiation and chemical treatment (pyraclostrobin + fluxapyroxad + metalaxyl, thiamethoxam + fludioxonil + metalaxyl-M + azoxystrobin or copper hydroxide 53.8%) on seed health and disease control. Microwave treatment decreased emergence <9%, but did not consistently improve the other parameters. Chemical treatment decreased disease symptoms, but did not provide season long control. Combining microwave and chemical treatments provided no additional disease control or economic benefit.