For cut-stump application, which layer of the tree should be treated?

In a cut-stump application, the focus is on treating the cambium layer of the tree. This is the critical area where the tree's growth occurs, and it is situated just beneath the bark. When a tree is cut, the cambium layer is exposed, making it vulnerable to potential regrowth of the plant. The cambium is responsible for producing new cells to form both the inner wood and the outer bark.

By applying herbicides to this layer immediately after the cut, it targets the active growth area of the tree and disrupts its ability to regenerate. This method is particularly effective because it allows the chemical to be absorbed directly where it can act most efficiently against the tree's vascular system, ultimately helping to prevent resprouting.

The outer bark provides some protection to the layers beneath it and wouldn't be effective for herbicide absorption. Heartwood, being the older, non-living core of the tree, does not contribute to its growth, thus treating it wouldn't address resprouting concerns. The inner bark, which is just inside the outer bark, also does not play a significant role in new growth in the same way the cambium does. Therefore, the cambium layer is the optimal target for cut-stump applications to ensure maximum