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Evidence for the Involvement of Soilborne Mites in Pythium Pod Rot of Peanut. H. D. Shew, Graduate Research Assistant, Department of Plant Pathology, North Carolina State University, Raleigh, 27650; M. K. Beute, professor, Department of Plant Pathology, North Carolina State University, Raleigh, 27650. Phytopathology 69:204-207. Accepted for publication 31 August 1978. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-204.

Mites of the genus Caloglyphus (Acarina: Acaridae) were associated with more than 50% of decaying peanut pods collected in a field in which pod rot was caused by Pythium myriotylum. Laboratory cultures of these mites could be maintained for several months on Pythium aphanidermatum growing on potato-dextrose agar slant tubes. In food preference tests Caloglyphus micheali was attracted to P. myriotylum; up to 98% of all mites responding in food preference tests preferred P. myriotylum over five other fungi isolated from peanut pods. Viable colonies of P. myriotylum were obtained from 90% of the fecal pellets collected from C. micheali after feeding on mycelial mats of the fungus. P. myriotylum oospores also remained viable after passing through the alimentary canal of C. micheali. Pythium pod rot was reduced significantly in field and greenhouse tests of several acaricides and broad spectrum insecticides. In greenhouse tests the addition of soilborne mites to field soil infested with P. myriotylum significantly increased the incidence of peanut pod rot.

Additional keywords: Pythium myriotylum, Caloglyphus spp.