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Disease Control and Pest Management

Bacterization of Rice Plants for Control of Sheath Blight Caused by Rhizoctonia solani. T. W. Mew, Plant pathologist, International Rice Research Institute, Los Banos, Laguna, Philippines; A. M. Rosales, research assistant, International Rice Research Institute, Los Banos, Laguna, Philippines. Phytopathology 76:1260-1264. Accepted for publication 24 March 1986. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1986. DOI: 10.1094/Phyto-76-1260.

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 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.