How to Kill Steeplebush

Dilute equal amounts of 41-percent glyphosate herbicide and water in a spray bottle or garden sprayer. The result will be a solution that is roughly 20-percent glyphosate herbicide. The herbicide must be mixed with water rather than a surfactant because a systemic herbicide such as glyphosate transpires through plant stems and into roots more easily when mixed with water than with a surfactant.

Cut all of the steeplebush's stems to about 6 inches above ground level, using a pair of bypass pruners or lopping shears.

Spray the stems that remain on the bush with the roughly 20-percent glyphosate herbicide solution until the stems are well-coated. Although you should spray the sides of the stems, concentrate the spray on the cut tips so the stems absorb the herbicide into the plant's roots.

Cover the sprayed stems with a tarp or sheet plastic for about 10 days. The material prevents the water-based herbicide solution from evaporating. Dig up the stems or turn them into the soil after 10 days, if desired, or allow them to decay naturally.

Monitor the area during the next few months for new sucker growth from the steeplebush. Persistent treatment for up to one year may be necessary to kill all of the plant's roots and prevent new suckers.

Allow a steeplebush sucker to grow to 1 to 2 feet long. Fill an empty aluminum can with the 20-percent glyphosate herbicide solution. Set the can on the ground near the sucker, and form a mound with soil, mulch or rocks to hold the can upright.

Cut the tip of the sucker, making an angled cut with bypass pruners. An angled cut has a longer surface area than a straight cut to absorb herbicide.

Push the sucker's cut tip through the aluminum can's tab and downward through the mouth of the can until it is fully submerged in the herbicide.

Remove the sucker from the can after two days. Cut the sucker to ground level. The sucker absorbs herbicide into the roots. The roots dry out, and eventually the entire root system dies.