Evaluation of seed treatments for the control of Colletotrichum lindemuthianum and Pseudomonas savastanoi pv. phaseolicola in organic production of bean: establishing test prerequisites

Abstract

Colletotrichum lindemuthianum and Pseudomonas savastanoi pv. phaseolicola cause anthracnose and halo blight, two economically important seed borne diseases of beans. Sanitation of seed can be an effective method to reduce and eliminate the presence of these pathogens. However, in organic agriculture, there are only limited seed treatments available, most of them being physical. Biological seed treatments, including three commercial formulations of bacterial and/or fungus consortia and two natural compounds against Colletotrichum lindemuthianum and Pseudomonas savastanoi pv. phaseolicola in beans are being developed. The methods included the evaluation of the inoculation rate of a C. lindemuthianum strain in beans cultivars, the effect of biological seed treatments on the germination of bean seeds, and DNA extraction methods used for bean seeds. Obtaining seeds with an adequate infection rate and extracting high quality DNA from bean seeds have proved to be difficult. Our study presents several challenges that restrict the development of seed treatments.