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Role of Benomyl in the Systemic Control of Fungi and Mites on Herbaceous Plants. P. M. Upham, Research Biologist, Biochemicals Department, Experimental Station, E. I. du Pont de Nemours & Co., Wilmington, Delaware 19898; C. J. Delp, Research Supervisor, Biochemicals Department, Experimental Station, E. I. du Pont de Nemours & Co., Wilmington, Delaware 19898. Phytopathology 63:814-820. Accepted for publication 17 January 1973. DOI: 10.1094/Phyto-63-814.

Radioautographs, combustion analyses, and bioassays show that up to 20 times more active compound enters and moves within herbaceous plants when 2-¹⁴ C-benomyl, rather than methyl 2-¹⁴ C-benzimidazolecarbamate (MBC), is applied to the leaf surface. The improved systemic and curative control of plant diseases with benomyl is due to this increased penetration and indicates that benomyl remains intact on treated plant foliage. Selected surfactants increase penetration. Movement of active components in the plant is predominantly with the transpiration stream. Cereal plants growing from treated seed have less chemical in each new leaf, and it is concentrated at the tips. Fungus spores and mites on plants treated systemically with ¹⁴C-benomyl contain high ¹⁴C concentrations.