Trunk Injection

Trunk injection is a targeted method of delivering treatments directly into a tree's vascular system. Small holes are drilled through the bark into the sapwood, and pressurized or gravity-fed injection devices introduce the treatment material into the xylem vessels. The tree's transpiration stream then distributes the product throughout the canopy.

This method offers several advantages over spraying. It eliminates drift and non-target exposure since the product stays within the tree. It is effective for very large trees that cannot be practically sprayed. It delivers precise doses directly to the vascular system where systemic diseases and pests operate. Common trunk-injected products include emamectin benzoate for emerald ash borer, propiconazole for Dutch elm disease, and iron compounds for chlorosis.

However, trunk injection does create small wounds in the bark and wood. Responsible practitioners minimize the number and size of injection ports and use proper techniques to promote rapid wound closure. The injection sites should be spaced around the trunk circumference and rotated in subsequent years to distribute any localized wood damage. The benefits of trunk injection for managing serious threats generally outweigh the minor wounding when performed by trained professionals using appropriate equipment.