Elm Bark Beetle Control on American Elm, 1979, 1980

American elms were sprayed hydraulically with methoxychlor to determine efficacy against twig-crotch feeding by the smaller European elm bark beetle, a vector of Dutch elm disease (DED). Experiments were conducted in each of 3 cities (Denver, CO; Warren, MI; Shaker Heights, OH). Treatment factors, replicated 3 times, were concentration (1, 2, 4%), sticker (Nu-Film-17, Vapor Gard, Rhoplex Ac-33, none), and season sprayed (fall, spring). Spray equipment and conditions were John Bean 785 gun, no. 14 disc, 39 kg/cm2 pressure,ca. 150 liters/tree, temperature 4.4° to 10°C, wind 0 to 12 km/hr, stickers at 1:800 final mix, and trees dormant. Forty twigs were collected at each tree level (top, middle, bottom) for bioassay. Fall-sprayed trees were sampled at 14 days postspray and at 12 months postspray. Spring-sprayed trees were sampled at 14 days postspray and at 6 months postspray. Beetles were caged in small cylinders on twig crotches and allowed to feed for 24 h at 30 ± 1°C and 88 ± 2% RH. Percentage of beetles that failed to feed to the xylem of twigs was used to measure effects of the treatments.