Using multi-service cover crops to control sunflower soil-borne pests

Session 4: Disease resistance and pest control

International audience

Английский. In France, sunflower cultivation is generally carried out in short rotations following a long fallow season when the soil is left bare. This practice not only causes nutrient leaching but also increases the phytosanitary pressure exerted on the crop. It notably leads to an increase in the soil seed bank of Orobanche cumana and inoculum of pathogenic fungi like Verticillium dahliae, which can remain in the soil for several years waiting for favorable germination conditions. Yield losses caused by these organisms are currently limited thanks to sunflower varietal resistance and chemical pesticides. However, this resistance can be overcome by the evolution of pathogen races, and the use of chemical pesticides must not become the norm. Biofumigation of selected multi-service cover crops implemented before the sunflower cultivation could be a promising method to regulate soilborne pests thanks to the natural toxic compounds they release. By simulating artificial biofumigation under controlled conditions using plant grinds, we evaluated the ability of three Brassicaceae species (Brassica juncea, Brassica rapa ssp. oleifera, Raphanus sativus) and one Fabaceae species (Vicia benghalensis) to inhibit the development of O. cumana and V. dahliae. These plants significantly inhibited the development of both pests compared to the control, with Brassica juncea showing the most pronounced effects achieving up to 100% inhibition. These results pave the way for a novel agroecological control method for sunflower soil-borne pests, which could complement ongoing breeding efforts for generating resistant sunflower varieties. The identification of the molecules responsible for this inhibition is currently under investigation.