Effect of Environment, Tree Size and Presence of Wetwood Symptoms on Injectability of American Elm

Abstract

During 1981 and 1982, 134 large elm trees growing on a college campus in Fargo, ND were injected with Arbotect for protection against Dutch Elm Disease. Chemical was applied at the “Minnesota 3X” rate using standard Elm Research Institute injection apparatus. Records were kept for tree size, condition, and wetwood symptoms and for amount of chemical applied and time required for uptake. Weather records were also compared. Findings for both years were similar. Time per tree for a full dose was nearly constant for trees of all sizes (25 cm to 95 cm diam). Individual trees were quite variable, the extreme cases differing six-fold. Injections on cool, cloudy or rainy days took longest and those on warm sunny days took least time. Presence of wetwood symptoms on the tree did not correlate with injectability.