Notes on brown sclerotium disease caused by Rhizoctonia oryzae-sativae on Zizania latifolia (manshurian wild rice)

Abstract

Lesions caused by Rhizoctonia oryzae-sativae on the leaf sheath of manshurian wild rice (Zizania latifolia Turcz.) varied in size from 1.3 to 4.5 cm long and from 0.4 to 1.0 cm wide. The lesions were fusiform to oblong, frequently coalesced, and ashcoloured with brown to dark brown beltshaped margins. The fungus, whose sclerotia are 638.9-775.2μm in diameter (major axis), grew well at 27 to 35°C and pH 5 to 8, and the best at 32°C and pH 7. R. oryzae-sativae derived from manshurian wild rice resembled closely to the fungus from rice plants as to these cultural characteristics. Moreover, the respective fungi from 2 different host plants produced almost the same type lesions on the leaf sheath of manshurian wild rice and rice plants, when inoculated alone. It was assumed that R. oryzae-sativae which causes rice brown sclerotium disease in paddy field is possible to induce the same disease on manshurian wild rice growing around the field.