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Prevention of Apothecial Formation in Gloeotinia temulenta by Systemic and Protectant Fungicides. John R. Hardison, Plant Pathologist, Plant Science Research Division, ARS, USDA, and Department of Botany and Plant Pathology, Oregon Agricultural Experiment Station, Corvallis 97331; Phytopathology 62:605-609. Accepted for publication 6 January 1972. DOI: 10.1094/Phyto-62-605.

Prevention of apothecial formation in Gloeotinia temulenta (blind seed disease) was studied in a greenhouse by application of 28 systemic and 26 protectant fungicides over infected seeds of Lolium perenne. For complete or a high degree of apothecial suppression, effective dosages per 92 cm² of soil surface for the most promising systemic compounds were: 1,2-bis(3-ethoxycarbonyl-2-thioureido)benzene, 1,2-bis(3-methoxycarbonyl-2-thioureido)benzene, parinol, and benomyl at 1 to 2 mg, and triarimol at 0.2 to 0.5 mg. Of the protectant-type fungicides tested, only four show promising activity. Cadmium succinate at 1 mg, cadmium chloride at 0.5 to 1 mg, phenyl-5,6-dichloro-2-trifluoro-methyl-1-benzimidazolecarboxylate (Lovozal) at 1 mg, and triphenyltin acetate at 2 mg gave either complete or nearly complete suppression of apothecia compared with a very high degree of control from benomyl at 1 mg and triarimol at 0.1 to 0.5 mg/92 cm² of soil surface. These nine compounds were vastly superior to the other chemicals tested, and justify field testing for elimination of ascosporic inoculum of G. temulenta to obtain field control of blind seed disease in grasses.