Towards a durable management of genetic resistances to

Blackeg is the major disease of winter oilseed rape in France. For an efficient control of the disease several tools could be combined, but mainly plant breeding has been used to increase winter oilseed rape resistance to blackleg. A useful step was reached in the nineties, using a specific resistance gene (Rlm1). After being widely used this resistance was broken down by an increase of the virulent sub-populations of the fungus. Such a situation worried the different actors and raised the question of the promotion of a durable management of genetic resistances to Leptosphaeria. After a synthetic presentation of the state of the art in the fields of genetics of resistance, of Leptosphaeria populations and on agronomic practices able to control the pathogen, the promotion of a durable management of resistances is discussed. This target needs to precise the strategy, to improve methodologies to characterise genotypes, to promote proper agronomic practices, to follow Leptosphaeria population behaviour and to motivate economic actors