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Field tests of 3-methyl-2-cyclohexen-1-one (MCH), the antiaggregation pheromone of the spruce beetle, Dendroctonus rufipennis Kirby, were conducted in south-central Alaska in stands of Lutz spruce, Picea x lutzii Little, and Sitka spruce, P. sitchensis (Bong.) Carr. The deployment of MCH in a novel releaser significantly reduced trap catches and spruce beetle attacks on standing live spruce by 96 and 87%, respectively. The results of this study demonstrate the first successful field test of MCH in Alaska for the prevention of spruce beetle attacks on standing, live spruce.

The dissipation and movement of carbaryl within soils of wet and dry sites in boreal (south central Alaska), temperate (north western North Carolina) and Mediterranean (east central California) ecosystems was determined by high-pressure liquid chromatography analyses at 1, 30, 60, 90, 365, and 485 d after applications of aqueous 2% to forest soils. Highest levels of carbaryl occurred within the uppermost soil layers of each site. The greatest carbaryl persistence was within the North Carolina dry site. All sites, with the exceptions of Alaska dry and North Carolina wet, had carbaryl levels exceeding 20 ppm in the upper layer of soil at 90 d. The decreasing order of carbaryl persistence was North Carolina dry > California wet > California dry> Alaska wet> North Carolina wet > Alaska dry. Only twice were replicated amounts of carbaryl found in the lowest soil layer (North Carolina dry, 60 d, Alaska wet, 1 d ) and these levels were only 5.6 and 5.1 ppm, respectively.

High-value trees, such as those located in residential, recreational, or administrative sites, are particularly susceptible to bark beetle (Coleoptera: Curculionidae: Scolytinae) attack as a result of increased amounts of stress associated with drought, soil compaction, mechanical injury, or vandalism. Tree losses in these unique environments generally have a substantial impact. The value of these individual trees, cost of removal, and loss of esthetics may justify protection until the main thrust of a bark beetle infestation subsides. This situation emphasizes the need for ensuring that effective insecticides are available for individual tree protection. In this study, we assess the efficacy of bifenthrin (Onyx) and carbaryl (Sevin SL) for protecting: ponderosa pine, Pinus ponderosa Dougl. ex. Laws., from western pine beetle, Dendroctonus brevicomis LeConte, in California; mountain pine beetle, Dendroctonus ponderosae Hopkins in South Dakota; and Ips spp. in Arizona; lodgepole pine, Pinus contorta Dougl. ex Loud., from D. ponderosae in Montana; pinyon, Pinus edulis Engelm. in Colorado and Pinus monophylla Torr. and Frem. in Nevada from pinyon ips, Ips confusus (LeConte); and Engelmann spruce, Picea engelmannii Parry ex. Engelm. from spruce beetle, Dendroctonus rufipennis (Kirby) in Utah. Few trees were attacked by Ips spp. in Arizona and that study was discontinued. Sevin SL (2.0%) was effective for protecting P. ponderosa, P. contorta, and P. monophylla for two field seasons. Estimates of efficacy could not be made during the second field season in P. edulis and P. engelmannii due to insufficient mortality in untreated, baited control trees. Two field seasons of efficacy was demonstrated in P. ponderosa/D. brevicomis and P. monophylla for 0.06% Onyx. We conclude that Onyx is an effective individual tree protection tool, but repeated annual applications may be required in some systems if multiyear control is desired.

Cones of blister rust-resistant western white pine were treated with highvolume ground applications of 0.025% fenvalerate during spring and summer 1984. Four treatments were compared: an untreated check, a single application (9 May), a double application (9 May and 13 June), and a triple application (9 May, 13 June, and 18 July). Dioryctria abietivorella (Grote) infested 46.6% of cones in the untreated check, significantly more than the 13.6% in the single application. The double application increased seed yield significantly compared to the untreated check from 31.3 to 56.0 seeds per cone. We are 95% confident that this treatment increased seed production by at least 30% and possibly as much as 128%. The third application in July was apparently unnecessary.

A large-scale field experiment was conducted to examine the efficacy of 1, 2, and 4% chlorpyriphos and 1,2, and 4% carbaryl for protecting high-value ponderosa pine trees from attack by Dendroctonus brevicomis LeConte. Each of the 510 trees utilized in the experiment was separated by at least 0.4 km. At 1 month, 3 months, and 1 year after insecticide application, D. brevicomis pheromone was attached to the boles of treated and untreated check trees. All six treatments were regarded as effective 1 month after application. At 3 months after application, 1 and 2% chlorpyriphos were regarded as ineffective. One year after application, low mortality of untreated check trees hindered the determination of efficacy of the remaining four treatments. At 3 months and 1 year after application, significantly more Temnochila chlorodia (Mannerheim) were found in catchment traps beneath treated than beneath untreated trees. The best explanation for this is insecticide-induced mortality of T. chlorodia . There were no significant differences in numbers of D. brevicomis or Enocleris lecontei (Wolcott) in the catchment traps.

The effectiveness of carbaryl in protecting high-value ponderosa pine trees from attack by Dendroctonus brevicomis LeConte was tested at reduced concentrations or for longer than one beetle flight season. A 2.0% suspension of carbaryl provided substantial protection of ponderosa pine from attack by D. brevicomis for the 5 months adults are actively attacking trees. Lesser concentrations, notably 1.0 and 0.5%, provided some protection but with greater tree mortality. Neither 2.0% Sevimol® nor 2.0% Sevin XLR® provided adequate protection for 9 or 12 months, respectively, after application.