Non-gramineous hosts ofMyriosclerotinia borealis

Abstract

On the basis of cultural, anatomical, and electrophoretic studies,Myriosclerotinia borealis (=Sclerotinia borealis) is shown to occur on cultivated non-gramineous plants includingIris ensata var.hortensis (Japanese iris),I. pseudoacorus, I. hollandica (Dutch iris), Perko PVH (a hybrid green manure crop betweenBrassica campestris andB. chinensis), Allium fistulosum, andCampanula portenshlagiana. The fungus did not kill these plants, but produced functional sclerotia, capable of carpogenic germination, on decayed leaves or necrotic lesions of overwintered leaves. The fungus seems to act as a saprophyte colonizing senescent leaves and/or as a weak parasite on plants injured by freezing during winter. In culture, the fungus produces discrete tuberoid sclerotia closely attached to the agar surface; rind differentiation is poor on the under surface of sclerotia. Medullary cells are embedded in a gelatinous matrix showing no distinct intercellular spaces. The ectal excipulum of apothecia produced under artificial conditions is composed of globose cells.Myriosclerotinia borealis is thus shown to be very close toCiborinia on the basis of these sclerotial and apothecial characters.