What layer of the tree is a trunk injection placed at or inside?

The trunk injection of a pesticide is placed at or inside the cambium layer of the tree. The cambium is a vital part of the tree's growth system, located just beneath the bark and responsible for producing new phloem and xylem cells. When pesticides are injected into the cambium, they have the potential to move through the tree's vascular system more effectively. This allows for better distribution of the chemical throughout the tree to combat pests or diseases.

The cambium layer serves as a connection point for nutrient and water transport between the outer layers of bark and the inner layers that support the tree's structural integrity. By targeting the cambium for injections, it ensures that the active ingredients can reach both the phloem and xylem, maximizing their effectiveness against various tree pests. The other layers, such as the xylem and phloem, are important for nutrient transport within the tree, but the cambium is the ideal site for initiation of systemic absorption when using injection techniques.