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A 24-Hour Deposition Sampler for Spores of Heterobasidion annosum. R. L. Edmonds, Professor, College of Forest Resources, University of Washington, Seattle 98195; R. W. Hinshaw(2), and K. B. Leslie(3). (2)(3)Electronics technician, and graduate student, respectively, College of Forest Resources, University of Washington, Seattle 98195. Phytopathology 74:1032-1034. Accepted for publication 26 April 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-1032.

A 24-hr deposition sampler for airborne spores of Heterobasidion annosum (Fomes annosus) is described. Twenty-four 60-mm-diameter disposable petri plates are mounted on a circular Plexiglas sheet. Once an hour the petri plates filled with selective medium are rotated beneath a 60-mm-diameter opening in the sampler cover. The Plexiglas sheet is rotated by a 24-position rotary solenoid (stepping motor) driven by two 6V light weight rechargeable gel batteries in series. Electronic circuitry for the sampler is described. The sampler was used in a western hemlock (Tsuga heterophylla) stand in western Washington to examine diurnal spore deposition patterns in June and October 1982. In October, most spores were deposited during the night and early morning, but in June there was no distinct pattern.

Additional keywords: root disease, spore sampler.