Things You'll Need
Hip waders (optional)
Unlike many other trees and plants, willows prefer moist soil and thus grow well near bodies of water such as ponds and streams. In fact, many willows actually grow in the pond itself with the roots completely submerged. If you decide to kill a pond willow, herbicides are not an option because they harm the wildlife and plants in the pond. Instead, use the girdling technique, which will kill the willow tree naturally.
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Wait until the late winter or early spring, just before the willow tree develops new green growth.
Position yourself next to the trunk of the willow tree. If the tree is in the center of the pond, this requires a boat. If the tree is near the bank, you may be able to use hip waders instead.
Examine the trunk of the willow tree to see if there is evidence of a water line above where the water currently sits. If a darker area of bark is seen above the existing water level, this indicates that the pond water may rise during the year.
Choose a location above the highest water line and insert the blade of a saw onto the bark, perpendicular to the trunk. Cut into the bark by at least 1/2 to 1 1/2 inches.
Continue cutting the willow trunk in this manner to create a circle all the way around it.
Return to the starting location and place the saw blade under the first cut line. For thin, small willow trees, place the saw 2 inches below the first line. For larger willow trees, place the saw 4 inches below the first line.
Cut another circle all the way around the willow tree trunk at the new location. The willow may still produce green leaves in the following months but will die completely soon after that.
You can also use a chainsaw to girdle the willow tree but be very careful not to drop it in the pond.