Penetration and infection of western larch seedlings by Botrytis cinerea

Abstract

The fungus Botrytis cinerea Persoon (ex Fries) is an important pathogen of container-grown conifer seedlings. The examination of whole mounts and serial sections of diseased needles of western larch (Larix occidentalis Nuttall) seedlings with a light microscope confirmed that the development of fungal infection structures conforms to that observed in nonconiferous hosts. Both stomatal and cuticular penetrations were evident. Infection hyphae displayed occasional taxis toward stomata on senescent needles but not on healthy needles. The treatment of seedlings with fungicides at levels corresponding to 1 and 10% normal application rates induced no consistent changes in fungal structures.