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Lignite and Stillage: Carrier and Substrate for Application of Fungal Biocontrol Agents to Soil. R. W. Jones, Former graduate research assistant, Department of Plant Pathology and Microbiology, Texas A&M University, College Station 77843, Present address: Dept. of Plant Pathology, University of California, Berkeley 94720; R. E. Pettit(2), and R. A. Taber(3). (2)(3)Associate professor, and research scientist, respectively, Department of Plant Pathology and Microbiology, Texas A&M University, College Station 77843. Phytopathology 74:1167-1170. Accepted for publication 9 May 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-1167.

A lignite-stillage carrier system was tested for applying biocontrol agents to the soil. Lignite was ground into granules (425- 2,000 μm) and twice amended with 50% (v/v) thin liquid stillage (TLS), a by-product of ethanol production. Two isolates of Gliocladium virens and one isolate of Trichoderma harzianum were used as test organisms. Seven days after inoculation, the colonized granules were air-dried and stored at 20 C. After 4 mo of storage, fungal viability remained >90% as determined by plating of granules. Colonized lignite-stillage carrier granules were applied in-furrow at a rate of 9.15 g/m to soil in growth boxes artificially infested with Rhizoctonia solani. Root rot ratings and root and shoot dry weights revealed positive effects of the biocontrol agents and carrier. One isolate of G. virens significantly lowered the incidence of damping-off and root rot caused in peanuts by R. solani; however, the incidence of damping-off and root rot were still significantly higher than in the noninfested control. Thin liquid stillage supported significant production of gliotoxin by G. virens in broth culture. Gliotoxin was not an important factor in suppression of R. solani; a gliotoxin-producing isolate of G. virens did not lessen damping-off or root rot as effectively as a non-gliotoxin-producing isolate.