La variabilité du pouvoir pathogène de Nectria ditissima agent du chancre du hêtre

Variability in the pathogcnicity of Nectria ditissima Tul. cause of beech canker. Four mycelial strains of Nectria ditissima Tul. were inoculated into young beeches of two different provenances. The size of bark necrosis was assessed monthly from December to June. The strains can be separated into three groups of aggressiveness according to the size of the necrosis, its persistence and also the hormonal disturbances resulting from pathogenesis. The results reported here suggest a differential interaction between N. ditissima and its host Fagus sylvatica.