How to Kill Trumpet Vines

Trumpet vine growing on a concrete building.
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Trumpet vine (Campsis radicans) is an attractive plant in the right place, but for many it's a nuisance. Rapidly growing up to 40 feet tall and 10 feet wide, trumpet vine is hardy in U.S. Department of Agriculture plant hardiness zones 4 through 9. Also called trumpet creeper, this vine spreads through underground runners and it self-seeds. Controlling trumpet vines involves controlling its roots and removing its seedlings.

Cutting Trumpet Vine

Cutting down trumpet vine is the first step in controlling this plant and discovering how far it's spread. Trumpet vine produces suckers, shoots that grow from a plant's roots, and where trumpet vine shoots touch the ground they grow roots and develop into new plants. Seedling plants can also appear wherever trumpet vine seeds drop from the vine.

Prune the trumpet vine's main stem as close to the ground as possible, and pull down the top growth from whatever structure it's clinging to. Sometimes removing all the top growth isn't possible, but it quickly wilts and dies when pruned from the roots. Examine the ground around the trumpet vine's main stem for suckers, and prune these at ground level. Check for trumpet vine seedlings in the area covered by the canopy and nearby. Pull or dig up the seedlings. After pruning trumpet vine, sterilize the pruning shear blades by wiping them with a cloth that was dipped in rubbing alcohol.

Treating Regrowth

Treating trumpet vine regrowth with glyphosate or tricolpyr controls the vine's roots. After trumpet vine top growth is removed, the plant quickly regrows from its deep and extensive root system. A piece of root less than 1 inch long can produce shoots in eight weeks, according to Purdue University Extension.

Glyphosate and tricolpyr are systemic herbicides, which travel through plants to their roots. Applying glyphosate, tricolpyr or a combination of the chemicals when the leaves on trumpet vine shoots have fully expanded controls the root system. Systemic herbicides damage most plants, so protect desired plants with cardboard, and spray on a still, dry day. Put on long pants, a long-sleeved shirt, safety goggles and gloves, and spray trumpet vine shoots with a ready-to-use herbicide that contains 1 percent glyphosate and 0.1 percent triclopyr, covering all the plant's parts.

Spraying Again

Applying herbicide to trumpet vine once is unlikely to provide full control and repeated spraying may be needed. Glyphosate and tricolpyr herbicides weaken trumpet vine root systems, but the plant may continue to produce shoots.

Every month, check the area where the trumpet vine was growing. When new shoots appear, wait until the leaves are fully expanded, and spray shoots with a ready-to-use glyphosate and tricolpyr herbicide. Painting trumpet vine leaves with herbicide using an old paintbrush helps prevent the herbicide from contacting desired plants. Trumpet vine regrowth is likely to be most vigorous in spring and summer.

Controlling Seedlings

Trumpet vine seedlings may appear in the area where the trumpet vine grew, but removing these by pulling them up or digging them up provides effective control. Trumpet vine seedling root systems are not deep or established while the plants are young, and the plants don't regrow providing the roots are removed whole.

Every month, check for seedlings in the area where the trumpet vine was growing. Firmly grip the seedlings at their bases, and pull them out of the soil. If the plants don't come up easily, dig beneath them with a trowel to loosen the roots.

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