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Use of Fluid-Drilling Gels to Deliver Biological Control Agents to Soil. Kenneth E. Conway, Associate Professor of Plant Pathology, Oklahoma State University, Stillwater 74078. Plant Dis. 70:835-839. Accepted for publication 24 March 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-835.

Use of fluid-drilling systems to deliver the biological control agents Trichoderma harzianum and Laetisaria arvalis with germinated vegetable seeds and as a slurry on apple seedlings was evaluated in field microplots. Delivery of sclerotia of L. arvalis with pepper seeds in gel increased stand counts in microplots containing fumigated soil infested with Rhizoctonia solani and significantly reduced the rate of preemergence and postemergence damping-off compared with unamended gel controls. In each of 2 yr, L. arvalis significantly reduced the rate of development of southern blight (Sclerotium rolfsii) on apple seedlings in infested plots compared with T. harzianum (first year) and unamended gel controls. During the first year, chlamydospores of T. harzianum added to gel provided complete control of southern blight for 86 days after planting, but disease subsequently progressed at a rate greater than in the unamended gel control. There were no significant differences between the biological control agents during the second year.