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Uptake, Translocation, and Efficacy of Triadimefon in Control of Turfgrass Pathogens. P. L. Sanders, Research Associate, Pesticide Research Laboratory, and the Department of Plant Pathology, The Pennsylvania State University, University Park, PA 16802; L. L. Burpee(2), H. Cole, Jr.(3), and J. M. Duich(4). (2)(3)Research Assistant, Professor, respectively, Pesticide Research Laboratory and the Department of Plant Pathology, The Pennsylvania State University, University Park, PA 16802; (4)Professor, Department of Agronomy, The Pennsylvania State University, University Park, PA 16802. Phytopathology 68:1482-1487. Accepted for publication 24 April 1978. Copyright © 1978 The American Phytopathological Society, 3340 Pilot Knob Road, St. Paul, MN 55121. All rights reserved.. DOI: 10.1094/Phyto-68-1482.

Rhizoctonia solani, Marasmius oreades, Corticium fuciforme, Fusarium nivale, and Sclerotinia homoeocarpa were sensitive in vitro to triadimefon (Bayleton®, BC 6447), with ED50 of ~1 μg active ingredient/ml potato-dextrose agar (PDA). In field tests, triadimefon provided excellent control of Sclerotinia dollar spot (S. homoeocarpa), Fusarium patch (F. nivale), stripe smut (Ustilago striiformis), Fusarium blight (F. roseum), and red thread (Corticium fuciforme); but it was ineffective against Helminthosporium leaf spot/crown rot (H. vagans). Residual activity of triadimefon appeared to be quite prolonged. In greenhouse tests employing direct inoculation of the plants with pathogen propagules, the chemical provided complete suppression of S. homoeocarpa on mature Kentucky bluegrass for 15 wk after fungicide treatment. In field tests, there was evidence of suppression of Sclerotinia dollar spot and stripe smut 1 yr after treatment with triadimefon. It is evident from greenhouse experiments that triadimefon, applied as a soil drench, is root-absorbed from a variety of soils and translocated acropetally in bentgrass, to provide protection against foliar pathogens. Efficacy of triadimefon on 10 experimental soil mixtures was greatest in sandy mixes and lowest in mixes high in clay content. There was no simple linear relationship between overall efficacy of triadimefon and pH, cation exchange capacity, or percolation rate of the 10 experimental mixes. Phytotoxicity of triadimefon on bluegrass and bentgrass varied with grass genus and cultivar.