Herbicides effectively kill trees and their root systems, but the plant must still be removed mechanically. Herbicides also have the potential to damage nearby trees and plants. Homeowners can usually remove small trees and roots themselves. For large trees, consult a tree surgeon trained in complete tree and root removal.
Several chemicals are labelled for use on tree stumps and roots. Dicamba, glyphosate, imazapyr, picloram and triclopyr will kill roots as well as the suckers that emerge from the trunk. Application methods and times vary somewhat, depending on the chemical. Read all packet directions carefully, and apply herbicides on a windless, sunny day.
Apply a herbicide to a freshly cut stump to kill the tree roots. Stumps quickly form a protective layer over any cut area, so immediate application is required for good penetration. Cover the entire surface of stumps less than 7.5 cm (3 inches) across. Cover the outer 7.5 cm (3 inches) of larger tree stumps only, allowing the herbicide to penetrate fully. You should apply herbicides in late spring to summer for best effect. Paint or spray any emerging suckers with glyphosate or triclopyr, and repeat as necessary.
Many trees, such as poplars, create a mass of shared roots underground. By applying herbicide to one tree, you'll likely kill other trees nearby. Even trees without a shared root system may have roots that become fused together underground, which usually occurs with trees of the same species. Herbicides applied on breezy days may drift to other trees and plants, causing damage. Although herbicides may kill roots, preventing new growth, the roots and stump remain in the ground long after the tree is gone, potentially constricting the growth of new plants.
Hire someone to grind tree stumps out with a stump grinder. Some of the roots may remain in the ground, but the stump and surrounding roots will be gone. Another option is to apply a root-rotting chemical to the stump, which hastens the natural rotting process.