336 the tree bole on the north side; the GLV/verbenone pouch (Synergy Semiochemicals, Burnaby, BC, Can- ada; Synergy Shield Pouch, Product No. 3413) was installed directly on the tree. Depending on tempera- ture, MPB adults may be active from May through October (USDA Forest Service 2015). Treatment and Tree Evaluations Trees were evaluated similarly for each experiment. The basic procedure was to treat in fall (except for experiment 3, which was treated in spring), bait with semiochemical attractants the following summer, conduct initial tree evaluations (crown fade and count attacks) in the fall (approximately 1 year post- treatment), and perform a final, crown-based evalua- tion of tree mortality the next fall (approximately 2 years post-treatment and 1 year post–beetle-attack-period). Because the majority of precipitation at our site is received during the winter and spring seasons, and MPB attacks were promoted into the fall, we made our crown assessments for fade after approximately 1 year had passed from the end of the baiting period. A similar protocol was used in Idaho by Haverty et al. (1998). Crown evaluations placed each tree into one of three categories: green (live), fading (stressed or dying), or faded (dead), with the latter category being indicated by red-brown crowns. Pitch tubes were counted at least once after baiting. In experiment 3, pitch tubes were counted on two sides of the bole within a rectan- gular area approximately 2812 cm2 at breast height. Prior to beetle emergence in the second year after treatment, two emergence cages (aluminum window screening 37 × 76 cm) were installed on opposite sides of each TREE-äge or control tree at about breast height to capture emerging beetles (Bentz 2006). In each case, cages were installed prior to brood emergence. In experiment 3, emergence cages were installed 20 to 21 May 2014. During fall of 2014 (approximately 16 months after treatment), emergence cages were removed, MPB collected, and the number of D. ponderosae attacks and emergence holes in the bark counted within the caged area (2 sides, each 2812 cm2 ; Table 2). Attacks were made prior to cage installation, and cages provided a well-delineated area for counting them. Bark samples (19 cm wide and 12 cm long) were removed from TREE-äge and control trees to estimate MPB activity by laboratory dissection. Using this method, attacks, adult galleries, larval galleries, and emergence holes were determined (Table 3). On ©2020 International Society of Arboriculture Table 2. Mean number of mountain pine beetle (Dendroc- tonus ponderosae) pitch tubes present (± SEM) in Pinus monticola (western white pine) among treatments observed on 30 July 2013 in experiment 3, 19 days after baiting. Pitch tubes were counted on two sides of the bole within a rectangular area (37 × 76 cm) 2812 cm2 at breast height. The untreated controls had the greatest number of pitch tubes, which differed significantly from the combination treatments. The lowest number of pitch tubes was observed on the TREE-äge and verbenone/green leaf volatile (V/GLV) treatment. The purpose of V/GLV is to decrease mountain pine beetle (MPB) attack by acting as an anti-aggregation pheromone. The dual purpose of the TREE-äge/PPZ treat- ment was to prevent MPB adults from successfully mining the phloem and to inhibit the development of pathogenic blue-stain fungi. Treatment Control TREE-äge/PPZ TREE-äge/V/GLV Tukey Pairwise Comparison. Means that do not share a letter are signifi- cantly different. 1 No. 10 10 10 No. of pitch tubes1 42.0 ± 3.1a 26.0 ± 4.0b 10.9 ± 2.3c Doccola et al: Emamectin Benzoate Efficacy Against Bark Beetles 25 August 2013, lures and GLV/verbenone repellents were changed. On 18 June 2014, phloem samples were again taken from the trees, and on 19 August and 15 October 2014, canopy assessments were conducted. Tree Autopsies Fading and faded trees (9 untreated controls and 7 TREE-äge-treated) from experiment 2 (injected 5 November 2009) were felled for autopsy on 27 October 2012, 2 years after they were baited to promote attack by MPB. Cross-sectional bole samples (approximately 10 cm thick) were collected from 3 to 12 m high in 3-m intervals using a chain saw. Samples (n = 63) were debarked, changes in the physical appearance of the vascular tissues were noted, and percentage of sapwood circumference blue-stained was calculated. Samples of xylem and phloem tissues were collected for culturing and identification. To quantify the relationship between injection fre- quency (circumferential distance between injection points) and colonization pattern by MPB, we evalu- ated trees from the first two experiments on 27 Octo- ber 2012 and the third experiment on 20 October 2015. For each tree, we measured the circumference at the base and breast height and the distance between injection points. This was followed by removal of the outer bark to expose the inner bark or sapwood face. Areas of exposed tissue were categorized as either colonized by MPB (at least one gallery > 2.5 cm in
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