Pressurized-Canister Trunk Injection of Acephate, and Changes in Abundance of Red Elm Bark Weevil (Magdalis armicollis) on American Elm (Ulmus americana)    (View PDF)

Michael Booth and Dan Johnson

Abstract: Portable pressurized injection vials (Ecoject System) were used in an experiment to assess injection of acephate into elm trees (Ulmus americana) as a means of reducing within-tree abundance of red elm bark weevil (REBW), Magdalis armicollis. A total of 25 elm trees were treated, each paired with an untreated tree. A total of 400 pressurized canisters were used in the study. REBW population density, as indicated by sticky-paper trap catches, on treated and untreated trees did not differ significantly at the time of trunk injection. Two weeks after injection, the average REBW trap catch on the 25 untreated trees had increased, whereas the average trap catch on the 25 treated trees had decreased. The resulting average trap catch from the treated trees was significantly lower than that of the control trees. Although subsequent declines in REBW populations precluded a longer record of the effects of tree injection, the significant reductions apparent in the first two weeks following injection indicated the method was effective in reducing REBW abundance. The impact on REBW populations was detectable even though treated and untreated trees were contiguous, indicating that selective treatment of individual trees could be part of an effective operational treatment for REBW management. No phytotoxic effects were detected by spectrophotometric assessment of leaf chlorophyll.

Keywords: Acephate; American elm; Canadian Prairies; Chlorophyll; Ecoject; Magdalis armicollis; Population Reduction; Red Elm Bark Weevil; Spectrophotometric; Sticky Trap Sampling; Trunk Injections; Ulmus americana

https://doi.org/10.48044/jauf.2009.026