At a time when environmental consciousness is not just fashionable but necessary for the health of our communities and planet, killing a tree may seem unreasonable. However, a weeping willow that damages sewage systems with its extensive roots, grows too large for your yard or drops branches indiscriminately is a hazard that requires drastic action. Both mechanical and chemical options exist for willow extermination. Use either method or a combination of both, depending on your expertise and comfort level. Before attempting any tree removal, check with the city and county public works department. Some trees on private property are considered “significant” or “landmark” and are protected by the municipal code.
Trim extending branches with a chainsaw or handsaw to prevent damage to surrounding structures and vegetation as the tree falls. Use extreme caution if operating the chainsaw while on a ladder.
Gather, bundle and remove the trimmed branches from your work area to prevent tripping hazards.
Cut the tree trunk close to the ground leaving the smallest stump possible. After the tree falls, cut the trunk into manageable pieces for firewood or disposal.
Use a stump grinder to break up the remaining stump and roots.
Passive Mechanical Method - Girdling
Cut a 1- to 1.5-inch-deep groove around the tree trunk just below the lowest branches using a chainsaw or ax.
Extend the groove until it is 6 to 8 inches wide, encircling the entire trunk and fully exposing the interior wood.
Monitor the cut regularly to ensure that the gap remains open and no heal-over occurs. This girdle prevents the flow of water and nutrients up the tree, which eventually kills it.
Apply tryclopyr to the lowest 18 inches of the willow trunk in early spring. Repeat this bark treatment application throughout the summer until mid-autumn at intervals recommended by manufacturer.
Spray-apply imazapyr or glyphosate to the foliage of trees under 15 feet tall following manufacturer’s instructions. Repeat the foliage application as recommended throughout the growing season.
Use a paintbrush to cover a newly cut stump with glyphosate. Repeat as recommended by the manufacturer to ensure that the herbicide reaches through the stump and into the roots. This step replaces the need for a stump grinder and has greater success in accessing and killing the willow’s widespread root system.
Apply herbicide by spray or paintbrush to the cut created by the girdling method to speed up the extermination process.
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Things You Will Need
- Protective eyewear
- Protective clothing (gloves, long-sleeved shirt, long pants)
- Mechanical stump remover (optional)
- Herbicide containing glyphosate, imazapyr or tryclopyr
- The girdling method can take a year or more to be fully effective. For best results, girdle the tree in spring or early summer.
- Before starting to cut, verify the falling branches will clear overhead wires and other structures.
- The chainsaw and stump removal method is recommended only for individuals trained in the use of this equipment.
- Read and follow the safety instructions for herbicide application. Confirm that your chosen herbicide is appropriate for your landscape and will not interfere with aquatic or other sensitive species.
- City and County of San Francisco Department of Public Works: Significant and Landmark Trees
- Washington State University Extension: Chemical Control for Woody Plants, Stumps and Trees
- USDA Natural Resources Conservation Service: Controlling Undesirable Trees and Shrubs Conservation Practice Information Sheet
- USDA Forest Services Pacific Northwest Region: Glyphosate Herbicide Information Profile
- University of Arizona Cooperative Extension: Cut Stump Application of Herbicides to Manage Woody Vegetation
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