Homeowners or landscapers may find themselves burdened by an unwanted or troublesome tree, shrub or vine and wish to kill the specimen and perhaps prevent regrowth. In addition to complete physical removal, there are several mechanical methods that can damage a tree, such as girdling or frilling, chemical control options or even some combination of the two.
Physical Removal and Cut Stump Treatment
An undesirable tree can be removed altogether using a saw, loppers or other machinery, depending on the size of the tree. However, resprouts will often occur if the root system is left intact. Prevent resprouts by treating the sapwood and bark of the cut tree with a water-soluble herbicide immediately following cutting. An oil-carried herbicide should be used for spring cuttings if the cut species has a heavy sap flow, like maple, or if application is occurring much later than cutting.
The process of girdling involves cutting a notch into the bark and wood that completely encircles the trunk. Use an axe,hatchet or saw to penetrate into the wood about an inch deep but more or less depending on the tree size. If using hatchet or axe, the width of the notch made by striking below and above the girdling line should be about a few inches wide. If chainsawing, make two horizontal girdles a few inches apart. The effectiveness of the girdle can be enhanced by a herbicide injection or application.
Frilling is a variation of girdling. With this method, performed with a hatchet or axe, a series of angled cuts are made downward into the tree, which is completely encircled. The partially severed bark and wood can remain attached to the tree. Frilling damage may heal over on particularly vigorous trees, but its effectiveness can be increased with a herbicide application.
Trees can be killed using tree injections, or introducing herbicide into the tree using an axe, hatchet or injector. Cuts from a tool can be spaced a few inches apart unless the tree species is especially hard to control. If using an injector or borer, follow manufacturer instructions to operate the tool and space cuts. Spray or inject water-soluble herbicides into the wounds according to the chemical manufacturer's instructions. Frilling and girdling can be combined with a water-soluble herbicide sprayed onto the wound. If herbicides are to be applied to a chainsaw girdle, only make one complete cut circle around the tree.
Basal Bark Spray
Basal bark herbicide application involves spraying the lower two feet of a tree trunk with herbicide. This method is best suited for small trees less than six inches in diameter, shrubs and vines and is intended to penetrate the tree bark, generally with an oil carrier and prevent basal buds that would otherwise sprout. When performing basal bark applications, take care to minimise runoff, as the chemical may damage the roots of nearby desirable trees.
Foliar herbicide treatments are sprays applied to the leaves and are only suitable for trees or brush under 15 feet tall. Avoid applications during hot weather, periods of water stress or when windy conditions could cause drift. Suitable herbicide active ingredients vary depending upon season.
Soil treatment, like foliar treatment, is best for killing a large number of unwanted trees in a small area. Evenly spread or narrow bands of herbicide solution are applied to the soil surface and move into the root zone following rain or irrigation.
- Ohio State University Extension; Controlling Undesirable Trees, Shrubs, and Vines in Your Woodland; Randall B. Heiligmann
- Washington State University Cooperative Extension; Chemical Control for Woody Plants, Stumps and Trees; Stott W. Howard and Robert Parker; Sept. 1995
- Wildlands Restoration Team; "Eradicating Eucalyptus, Acacia, and Other Invasive Trees"; Ken Moore; March 2008