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A Self-Inhibitor in Uredospores of the Coffee Rust Fungus. Maria Raphaela Musumeci, Fellows of Conselho Nacional de Pequisas, Instituto Biólogico, São Paulo 01000, Brazil, S. A.; Walkyria B. C. Moraes(2), and Richard C. Staples(3). (2)Fellows of Conselho Nacional de Pequisas, Instituto Biólogico, São Paulo 01000, Brazil, S. A.; (3)Boyce Thompson Institute, Yonkers, New York 10701, U. S. A. (R.C.S.). Phytopathology 64:71-73. Accepted for publication 3 July 1973. DOI: 10.1094/Phyto-64-71.

Uredospores of the coffee rust fungus (Hemileia vastatrix) were shown to contain a potent self-inhibitor. The compound was extracted from the spores with water, partitioned into ether, and chromatographed on thin-layer plates of silica gel. The compound had an Rf =0.3 in a benzene:ether solvent (80:20, v/v) system, and the extract from 2 mg of spores was required to obtain the ED₅₀. Neither of the known self-inhibitors from spores of two other species of rust fungi (Puccinia spp. and Uromyces spp.) effectively inhibited germination of H. vastatrix uredospores.