Investigation of the host ranges of the leaf blotch pathogens of onion (Cladosporium allii-cepae) and leek (C. allii)

Inoculation of a range of Allium species and two non-alliaceous species with isolates of Cladosporiumallii-cepae and C. allii , obtained from onion and leek, respectively, demonstrated that the two pathogens had distinct host ranges. Conidia of C. allii-cepae, applied either dry or in aqueous suspension, infected A. altaicum, A. fistulosum (Japanese bunching onion), A. cepa (bulb onion), A. cepa var. ascalonicum (shallot), A. galanthum, A. pskemense and A. vavilovii . Dry conidia of C. allii applied at a high concentration caused atypical necrosis on A. altaicum, A. fistulosum, A. cepa var. ascalonicum, A. galanthum, A. pskemense, A. vavilovii, A. sativum (garlic), A. ampeloprasum and A. porrum (leek). Only A. ampeloprasum and A. porrum became typically infected following inoculation with conidia applied dry at low concentration or in aqueous suspension. Isolates of C. allii from leek failed to infect A. vineale, the type host. The length of conidia of a single isolate of C. allii-cepae varied significantly on different Allium spp.