Bacterization of Rice Plants for Control of Sheath Blight Caused byRhizoctonia solani

Abstract

Bacteria that produced fluorescent and nonfluorescent pigment on Kings Medium B and showed antagonism to Rhizoctonia solani, which causes rice sheath blight, were found in rice [Oryza sativa] fields. Antagonists were isolated from sclerotia, rice field flood water, rhizosphere soils of upland and lowland fields, and diseased and healthy plants. Both fluorescent and nonfluorescent bacteria inhibited mycelial growth of the pathogen, affected sclerotial viability, and slightly promoted rice seed germination. When used in seed bacterization, the antagonists suppressed the disease and protected the plant from infection. Subsequent planting after the first crop, in which the seeds were treated with the bacteria, on the same soil also showed reduced disease severity. The bacteria appeared to establish in the soil after sowing of seeds treated with antagonistic bacteria.