Three metabolites designated Cyl-1, -2 and -3 were isolated as plant growth regulators from culture filtrate of Cylindrocladiunr scoparium Morgan, a phytopathogenic fungus. Cyl-2 was obtained as pure crystals, and it revealed marked inhibitory activity on the root growth of lettuce seedlings. Cyl-1 showed inhibition on the same organ, while Cyl-3 showed promotion.
