Studies on Botrytis spp. occurring on onions (Allium cepa) and leeks (Allium porrum).
B. byssoidea (mycelial neck rot) was more prevalent than B. allii (sclerotial neck rot) on the leaves of field onions and the bulbs of stored onions grown in some of the areas where onions or onions and leeks had previously been grown sequentially. G. byssoidea and B. porri were also isolated from leeks. Spores of B. allii, B. byssoidea (from onions and leeks), B. porri and B. [Sclerotinia] squamosa caused infection of seedlings of salad (green) and bulb onions. Inoculation with S. squamosa spores caused severe infection of seedling leaves, but inoculation with mycelial discs caused little damage to onion bulb tissue. By comparison, mycelial discs of the remaining spp. were highly pathogenic to bulbs. The practical implications of disease transfer of certain of these spp. between onions and leeks are discussed.