150 Booth and Johnson: Trunk Injection of Acephate on American Elms CONCLUSION Although the declines of red elm bark weevil populations lat- er in the season precluded a longer record of the effects of tree injection, the method was effective in delivering sufficient ac- tive ingredient to the target to reduce REBW numbers in the elm trees. The result was detectable even though treated and untreated trees were contiguous, typically on the same side of a paved lane. No phytotoxic effects were apparent. Future stud- ies could be conducted to determine the dynamics of active in- gredient concentrations in leaf and wood tissue, to compare the results of a range of rates, and to determine rates that would be required for economical and effective operational-scale control. Figure 2. Typical absorbance spectrum (Biochrom Ultrospec 3300 pro UV/Visible spectrophotometer) for one elm leaf sample (tree 7, date 2). On later dates, the populations of all blocks and both treatments declined, resulting in more frequent “zero” counts and treat- ment differences were no longer measurable after that time. The sampling scheme in our experiment did not distinguish between mortality and possible consequence of repellency. Relative Population Changes sure has been shown to be a reliable indicator of adjusted changes in pest abundance (often interpreted as mortal- ity), applicable to randomized complete block designs sam- pled over time in field studies, such as this, and confirmed in Monte Carlo simulation studies (Schaalje et al. 1986). The more rapid drop in the REBW counts on the treated trees (T), with respect to that of the untreated control trees (C), during the first two weeks after injection, resulted in a decline in abundance of 36.7% on the treated trees, ad- justed against the change on the control trees. This is an adjusted value (Abbott 1925), calculated as 100 * (1 - odds ratio), where the odds ratio is (T2 *C1 )/(T1 *C2 Table 1. Numbers of valid (not blown down by wind) sticky traps, and mean numbers of REBW per trap, during the first two weeks following injection. a. At the time of injection n treated control 116 116 b. Two weeks post-treatment n treated control 102 93 mean 0.3103 0.4138 mean 0.2451 0.5161 SEM 0.05254 0.06825 SEM 0.05107 0.08596 Acknowledgments. Funding, resources and personnel were provided by a Canadian TREE (Tree Research & Education Endowment) Fund Jack Kimmel Grant in 2006, and by the Lethbridge Research Centre. Labora- tory analysis and field assistance were provided by University of Leth- bridge research staff, with the support of Canada Research Chairs. Sam Wind and Jenn Dorn assisted by assistance with sticky trap examination and spectrophotometric analysis, respectively. We thank the Internation- al Society of Arboriculture (ISA) Prairie Chapter for their support and encouragement. LITERATURE CITED Abbott, W.S. 1925. A method of computing the effectiveness of an insec- ticide. Journal of Economic Entomology 18:265–267. Doccola, J., P.M. Wild, I. Ramasamy, P. Castillo, and C. Taylor. 2003. Efficacy of arborjet viper microinjections in the management of hem- lock wooly adelgid. Journal of Arboriculture 29:327–330. Doughty, S.C., D.K. Pollet, R.J. Constantin, D.W. Wells, and K.L. Koonce. 1992. Paint– on application of acephate for aphid control on crapemyrtle. Journal of Arboriculture 18:94–97. Gill, S., D.K. Jefferson, R.M. Reeser and M.J. Raupp. 1999. Use of soil and trunk injection of systemic insecticides to control lace bug on hawthorn. Journal of Arborculture 25:38–42. ). This mea- Health Canada, Pest Management Regulatory Agency. 2004. Re-evalua- tion of Acephate. PACR2004-40. 68 pp. Ottawa, Canada. www.pmra- arla.gc.ca Johnson, D.L., 1983. On the relationship between the European red mite and apple leaf chlorophyll. Journal of the Entomological Society of British Columbia 80:42–45. Knudson, L.L., T.W. Tibbitts, and G.E. Edwards. 1977. Measurement of ozone injury by determination of leaf chlorophyll concentration. Plant Physiology 60:606–608. SAS Institute, 2007. SAS Ver. 9.1 and JMP Ver. 5.1 Saunders, C., M.D. Wartenbe, and W.B. Barr. 2004. Drought stress prob- lems in Edmonton’s Forest. 6th Canadian Urban Forest Conference, Oct 18–23, 2004, Kelowna, BC. (www.treecanada.ca/cufc6/proceed- ings/papers/Saunders.pdf) Schaalje, G.B., W.A. Charnetski, and D.L. Johnson. 1986. A comparison of estimators of the degree of insect control. Communications in Sta- tistics: Simulations and Computations 15:1065–1086. Tipping, P.W., and T.D. Center. 2002. Evaluating acephate for insecticide exclusion of Oxyops vitiosa (Coleoptera: Curculionidae) from Mela- leuca quinquenervia. Florida Entomologist 85:458–463. ©2009 International Society of Arboriculture
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