VIEW ARTICLE

Uptake and Translocation of Systemic Fungicides by Soybean Seedlings. L. E. Gray, Research Plant Pathologist, Crops Research Division, ARS, USDA, Soybean Investigation, University of Illinois, Urbana 61801; J. B. Sinclair, Professor, Department of Plant Pathology, University of Illinois, Urbana 61801. Phytopathology 60:1486-1488. Accepted for publication 5 May 1970. DOI: 10.1094/Phyto-60-1486.

Five fungicides known to be systemic in plants other than soybean (Glycine max): benomyl [methyl-1-(butylcarbamoyl)-2-benzimidazolecarbamate, E. I. duPont's Benlate]; chloroneb (1,4-dichloro-2,5-dimethoxyl benzene, E. I. duPont's Demosan); DCMOD (2,3-dihydro-5-carboxanilido-6-methyl-1,4-oxathiin-4,4-dioxide, UniRoyal's Plantvax); and DMOC (5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilido, UniRoyal's Vitavax) were fungitoxic to the following soybean pathogens: Diaporthe phaseolorum var. caulivora; D. phaseolorum var. sojae; Cercospora kikuchii; and Cephalosporium gregatum in vitro. TBZ [2-(4'-thiazolyl) benzimidazole], was fungitoxic to D. phaseolorum var. sojae. TBZ was not evaluated against the other three pathogens. Some fungitoxic component of benomyl, chloroneb, and TBZ moved systemically in soybean seedlings after seedling roots were exposed to the chemicals. It was not ascertained whether the specific fungicide or a compound related to it accounted for fungitoxicity in treated seedling tissues. DCMOD and DMOC were phytotoxic at the levels tested, and could not be bioassayed for systemic activity. Benomyl and TBZ tended to accumulate in the cotyledons of treated seedlings, but not in the hypocotyl tissues. This may account, in part, for the general lack of success in using these fungicides as seed and soil treatments for disease control in soybean seedlings.