Hole Angle for Trunk Injection of Tree Growth Regulators and its Effect on Weeping, Wound Closure and Wood Discoloration    (View PDF)

Therese A. Wasniewski, William R. Chaney and Harvey A. Holt

Abstract: The effects of gibberellin synthesis inhibitors injected into tree trunks on wound exudation, wound closure, and wood discoloration were determined at various times up to 23 months after treatment. Plantation grown Liriodendron tulipifera trees located in Tippecanoe County, Indiana received fourtreatments; injection of CutlessTP or Clipper 20 UL in holes drilled at an angle (45°) or straight into the tree. A special injector tip was created for the straight injections. Injection holes drilled at 45° began weeping sooner and tended to have a higher percentage of weeping during nondormancy periods than those drilled straight into trees. Holes injected with Cutless began weeping sooner and a higher percentage wept than holes injected with Clipper. Less than one percent of the total volume of wood in tree trunks was discolored by injection treatment. The amount of wood discolored was not influenced by the compass orientation of the injection hole and was the same for treatment with either Clipper or Cutless. Straight-in injections caused more discolored wood than angle injections only in trees sampled 12 months after treatment. No difference was found in wound closure rates due to the different tree growth regulators or the angle of injection. The only benefit of making injection wounds straight into trees was a slight reduction in weeping.

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https://doi.org/10.48044/jauf.1993.022