Tree injection

Tree injection, also known as trunk or stem injection, is a method of target precise application of pesticides, plant resistance activators, and fertilizers into the xylem vascular tissue of a tree with the purpose of protecting the tree from pests or nutrition for correction of nutrient deficiencies. This method largely relies on harnessing the tree’s vascular system to translocate and distribute the active compounds into the wood, canopy and roots where protection or nutrition is needed. Tree injection is currently the most popular method for control of damaging insects, pathogens, and nematodes in landscape tree care. It has been developed primarily for use on large size trees and in proximity of urban areas where ground- and air-spray applications are impractical due to substantial drift-driven pesticide losses or not allowed due to potential human exposure. However, the prime driver of tree injection use has been a wide spread need for control of many invasive tree pathogens and insects pests. The most infamous examples are that of Ophiostoma fungi that cause Dutch Elm Disease (DED) and insect Emerald ash borer (Agrilus planipennis) which have specific biologies that lead to severe internal damage of wood and thus tree death, and which make their management extremely difficult or inefficient with classical pesticide application methods. Trunk injection for tree protection is viewed as environmentally safer alternative for pesticide application since the compound is delivered within the tree, thus allowing for selective exposure to plant pests. In landscapes and urban zones trunk injection significantly reduces the non-target exposure of water, soil, air, and wildlife to pesticides and fertilizers. In the last 20 years, tree injection is gaining momentum with the development and availability of new, efficient injection devices and injectable and xylem mobile formulations of pesticides, biopesticides and nutrients. Further, a number of newly occurring and fast spreading invasive insect pests and diseases such as Polyphagous Shot Hole Borer (PSHB) Euwallacea sp., which vectors plant pathogenic fungus Fusarium euwallaceae, and Sudden Oak Death (SOD) caused by an Oomycete Phytophthora ramorum, establish the use of trunk injection as the most efficient tree protection technique in landscapes and urban forestry.