342 Doccola et al: Emamectin Benzoate Efficacy Against Bark Beetles Table 4. Summarized data of felled western white pine in experiment 3 as of 21 October 2015, where 7 of 10 trees per treatment were autopsied. The percent of bole height to percent circumference attacked by MPB and stained phloem was calculated. The controls had the greatest staining with a mean of 55.6% of tree height, which differed significantly from the TREE-äge/V/GLV trees with only 21.2% of bole height stained. The TREE-äge/PPZ-treated trees were intermediate, with 38.3% of bole height stained. Likewise, the controls had the greatest mean square meter of phloem blue-stained, followed by TREE-äge/PPZ and TREE-äge/V/GLV, but these were not significant. Of the dead (n = 10) trees, 49.9% of bole height was blue-stained, which was significantly different from the live (n = 11) trees with 27.9% of bole height stained. Furthermore, mean square meter area of live and dead trees (3.2 ± 1.9 SD and 6.4 ± 2.9 SD, respectively) was statistically significant. Grouping information used the Tukey method and at the 95% confidence level. Treatment Control TREE-äge/PPZ TREE-äge/V/GLV No. live/dead of trees autopsied 0/7 5/7 5/7 1 Means that do not share a letter are significantly different. In our study, movement of AI into phloem tissue was confirmed with both biological and chemical evaluations. Pressure by MPB was high, providing an excellent opportunity to examine phloem for areas with biologically active or inactive concentrations of EB. In experiment 2, we did not observe signs of suc- cessful MPB reproduction. Residue concentrations were high, and adult MPB galleries were mostly absent except for initial attacks. This observation sug- gests that the injection procedures used in 2009 and in 2013 may be useful for assessing the relative Table 5. In experiment 3, trees were treated on 11 June 2013. The treatments included TREE-äge plus propiconazole (PPZ), TREE-äge with verbenone and green leaf volatile (V/GLV) to deter MPB attack, and untreated controls. Change in tree condition and percent tree mortality were observed over time in this experiment. Evaluations of trees included rating the canopy qualitatively as green (live), fading (stressed or dying), or faded (dead). Evaluations were conducted at 14 months (on 19 August 2014), at 16 months (on 15 October 2014), and at 28 months after treatment (on 21 October 2015). Final evaluations were conducted on 21 October 2015. Treatment TREE-äge/PPZ TREE-äge/V/GLV Control *1 fading. ©2020 International Society of Arboriculture Evaluation date 19 August 2014 15 October 2014 21 October 2015 19 August 2014 15 October 2014 21 October 2015 19 August 2014 15 October 2014 21 October 2015 % mortality 0% 0% 20%* 10% 10% 20% 100% 100% 100% contributions of different organisms to the death of pines attacked by MPB. High levels of attack pressure are the most likely conditions to require management interventions with insecticides and they are also the conditions during which efficacy is least likely to be attained. This is particularly noteworthy for systemics, because each attacking insect must contact some amount of phloem tissue, and usually ingest it, for insecticides to be debilitative or lethal. We have determined from isolates of trees autop- sied in experiment 2 that two species of fungi, G. clavigera and L. longiclavatum, can negatively impact tree health, and our observations and those of Gros- man et al. (2009) suggest that bark beetle associated fungi successfully colonize trees treated with TREE- äge even without beetle success. Whether or not com- bination treatments can be developed to address these factors (e.g., TREE-äge injection plus a fungicide like propiconazole to reduce fungal establishment) was the focus of experiment 3. Increasing treatment effec- tiveness was dependent upon identifying the organ- isms that contribute to tree death (bark beetles and fungi), developing treatments that impact them, and on improving our knowledge of the relationship between treatment efficacy and quantifiable beetle pressure. In experiment 3 (evaluated 21 October 2015), 2 years and 4 months after treatment, none of the untreated controls survived, whereas 80% of the TREE-äge- and GLV/verbenone-treated trees and the TREE-äge/PPZ-treated trees remained alive (Table 5). For each assessment period (August 2014, October Mean % height stained1 55.56 a 39.10 ab 21.18 b Mean % circumference discolored 65.1 a 35.0 a 33.7 a Mean m2 sapwood discolored 6.17 a 4.91 a 3.04 a
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