Biocontrol of fungal plant diseases using bacterial culture extracts
Résumé
Biocontrol is based on agents and products using natural mechanisms in integrated pest management. Biocontrol products are divided in four categories: macro-organisms, micro-organisms, chemical mediators such as pheromones and natural substances of mineral, plant, animal or microbial origin. Although natural substances of microbial origin are promising biofungicides, only few of them are marketed as biocontrol products. Our work proposes to develop new biocontrol products based on lipopeptides from bacteria Bacillus or Pseudomonas to fight against fungal pathogens of crops such as Botrytis cinerea (gray mold of grapevine and tomato), Sclerotinia sclerotiorum (white rot of rapeseed and sunflower) and Zymoseptoria tritici (Septoria tritici blotch). The strains were first tested in vitro for antagonistic effect against several fungal pathogens. Then, the active strains were used to produce bacterial culture extracts. Crude culture extracts containing known and novel forms of lipopeptides were tested in planta by spraying on the leaves of wheat grown in a greenhouse. They reduced efficiently Septoria tritici blotch.