Powdery Mildew on Jew's Marrow, Corchorus olitorius L.

Abstract

In the autumn of 1997, a powdery mildew of Jew's marrow was found in Mie prefecture, Japan. White, powdery mycelia appeared on leaves, pods and shoots. Conidia with fibrosin bodies were ellipsoid to elongate-ellipsoid, 31.2-41.6×16.5-20.8μm and formed in chains. Conidiophores were erect on superficial mycelium, 67-125μm in length. Germ tubes from conidia were simple, not branched. No cleistothecium was observed. Based on the conidial stage, the fungus was identified as Oidium sp. of the Sphaerotheca fuliginea type.