S03 - Session O2 - Evaluation of seed treatments for the control of Colletotrichum lindemuthianum and P. savastanoi pv. Phaseolicola organic production of bean: establishing the tests "prerequisite"

Authors: Carlo Gamper Cardinali *, Joelle Herforth-Rahmé

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 mean to reduce and eliminate the presence of the pathogen. However, in organic agriculture, there are only limited seed treatments available, most of them being physical. One of the objectives of the H2020 project BRESOV is to develop protocols and tools to ensure high sanitary quality of organic seeds. In this task we evaluate diverse biological seed treatments including three commercial formulations of bacterial and/or fungus consortia and one to two natural compounds (e.g. mustard oil extract), next to standard physical seed treatments such as warm water, against Colletotrichum lindemuthianum and Pseudomonas savastanoi pv. Phaseolicola in beans. We use naturally infected as well as artificially inoculated seeds to isolate pathogens, test the different seed treatments and finally obtain treatments which do not impact seed germination but reduce or eliminate the infection. Post-treatments tests are conducted following ISTA protocols and molecular detection techniques. The effect of the test treatments is quantified and those particularly effective are possibly validated by seed producer(s).