How much of a tree's stem or trunk should be sprayed for effective basal applications?

For effective basal applications, spraying the bottom 2 feet (24 inches) of a tree's stem or trunk is recommended because this area is where the herbicide is most likely to penetrate the bark and reach the vascular system of the tree. The herbicide needs to be applied low on the trunk since this is typically where the tree is still in a juvenile phase and is therefore more susceptible to the effects of the chemical treatment.

Applying to the entire trunk length or to the upper portion of the trunk may not be as effective, as the target area for absorption is concentrated near the ground level where the cambium layer is active and accessible. This targeted approach minimizes herbicide use while maximizing effectiveness on the tree species intended for control, making it a best practice in managing invasive plants or unwanted tree species.