Which application method would be used for controlling a tree with a trunk diameter larger than 5 inches?

The cut-surface treatment is the appropriate application method for controlling a tree with a trunk diameter larger than 5 inches because it involves making precise cuts into the tree, usually at the base or on the sides, and then applying a herbicide directly to the cut surfaces. This method is particularly effective for larger trees, as it ensures that the herbicide penetrates the inner tissues of the tree where it can be most effective.

This method targets the vascular system of the tree, allowing the toxic material to be transported throughout the plant, ultimately leading to its death. For larger trunks, this technique is essential because other methods, such as foliar applications or basal bark applications, may not deliver the herbicide effectively enough given the size and structure of the tree, which could lead to inadequate control.

In contrast, foliar application is generally reserved for smaller trees or plants with accessible leaves, basal bark treatments are effective when the trunk is comparatively smaller (typically less than 6 inches in diameter), and contact treatments are primarily for species that can be easily reached and treated directly on their foliage or stems.