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Relationship Between Nitidulids and Ceratocystis fagacearum During Late Summer and Autumn in Minnesota. Jennifer Juzwik, Forest Pathologist, Pest Control Section, Ministry of Natural Resources, Maple, Ont., Canada L0J 1E0. D. W. French, Professor, Department of Plant Pathology, University of Minnesota, St. Paul 55108. Plant Dis. 70:424-426. Accepted for publication 25 November 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-424.

Free-flying nitidulids (Coleoptera: Nitidulidae) were collected from an oak wilt area in Minnesota from 30 August to 22 October 1982. Ceratocystis fagacearum was isolated from two of 1,145 (0.17%) beetles. None of 11 oaks with nitidulids (collected from sporulating mats) caged over wounds wilted; however, two of five oaks receiving 1 ml of a water wash of similarly collected beetles in a fresh wound wilted. About 3,300 nitidulids marked with fluorescent powder were released near wounded trees in September and October. Marks indicating insect visitation as well as marked beetles were found in wounds on eight trees during the 11 days after release. Unmarked nitidulids were collected from wounds on three trees. From these observations, nitidulids might transmit C. fagacearum to susceptible oaks during late summer and autumn in Minnesota, but this is probably rare.