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Uptake of Two Systemic Fungicides and Their Breakdown Products by Soybean Seeds. B. L. Kirkpatrick, Graduate Research Fellow, Department of Plant Pathology, University of Illinois, Urbana 61801, Senior author's present address: Department of Botany, University of Illinois, Urbana 61801; J. B. Sinclair, Professor, Department of Plant Pathology, University of Illinois, Urbana 61801. Phytopathology 63:1532-1535. Accepted for publication 25 July 1973. DOI: 10.1094/Phyto-63-1532.

The growth of Macrophomina phaseolina (Rhizoctonia bataticola) on potato-dextrose agar (PDA) containing 5, 10, or 50 µg/ml of the systemic fungicides BD 18654 [methyl (1-(((5-cyanopentyl)amino)carbonyl)-1H-benzi-midazole-2-yl) carbamate] and TM [thiophanate-methyl = 1,2,-bis-(3-methoxy carbonyl 1-2-thioureido)benzene] was significantly less than controls. Thin-layer chromatography detected BD 18654 and a breakdown product in fresh aqueous solutions; the former but not the latter was heat-stable. M. phaseolina and Penicillium atrovenetum were sensitive to both compounds in vitro. TM was stable for 1 wk in an aqueous solution, but yielded a breakdown compound, possibly methyl 2-benzimidazole carbamate (MBC), during autoclaving. M. phaseolina was sensitive to both of these compounds, but P. atrovenetum was sensitive to only MBC. The four compounds, BD 18654 and its breakdown product, and TM and its breakdown product (MBC), were absorbed by germinating soybean seeds within 4 hr. Charcoal rot was not controlled if seeds were treated with either BD 18654 or TM at 5 and 10 g/kg.

Additional keywords: seed treatment.