Characterization of Clubroot Pathotypes in France and Development of a Resistance Test for Oilseed Rape

Clubroot, caused by the soil-borne pathogen Plasmodiophora brassicae, severely reduces yield in Brassica crops by inducing root galls that disrupt water and nutrient uptake. This research collected 70 field isolates across key French production areas to characterize pathotypes P1 through P6, revealing P1, P2 and P3 as dominant. Several isolates overcame the reference resistant variety ‘Mendel.’ Based on these findings, representative isolates of P1–P3 were selected to develop a comprehensive resistance testing protocol. Proposed to the French variety registration committee (CTPS), this protocol is now implemented by GEVES for official oilseed rape variety registration.