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Systemic Activity of Methyl 2-Benzimidazolecarbamate (MBC) in Almond Blossoms Following Prebloom Sprays of Benomyl + MBC. Donald C. Ramsdell, Research Assistant, Department of Plant Pathology, University of California, Davis 95616, Present address of senior author: Department of Botany and Plant Pathology, Michigan State University, East Lansing 48823; Joseph M. Ogawa, Professor, Department of Plant Pathology, University of California, Davis 95616. Phytopathology 63:959-964. Accepted for publication 5 February 1973. DOI: 10.1094/Phyto-63-959.

Prebloom sprays of proprietary benomyl 50W afforded excellent control of Monolinia laxa blossom and twig blight of almond (cultivar ‘Drake’). Sprays of 2.80 and 1.40 kg/hectare (2.5 and 1.25 lb/acre) benomyl 50W with or without oil were equally effective. Bioassays performed with conidia of M. laxa following prebloom sprays showed all blossom parts were protected through full bloom. Methyl 2- ¹⁴C-benzimidazolecarbamate (¹⁴C-MBC) plus benomyl 50W applied with or without oil to branches of covered trees at green-bud or pink-bud stages resulted in radioactivity in all blossom parts at full bloom. Labeled and unlabeled MBC were the only residues recovered from such blossoms, indicating degradation of benomyl to MBC under field conditions. Benomyl and MBC were similar in degree of fungitoxicity to M. laxa conidia.