Chinese and Japanese Wisteria (Wisteria sinensis, Wisteria floribunda)
Wisteria is a trendy ornamental plant with gorgeous flowers and a rapid growth rate. Unfortunately, it has proven capable of escaping cultivation and invading natural environments, where it can smother trees and stop normal forest succession. Wisteria should never be planted, as many excellent native alternatives exist, and existing wisteria should be removed to prevent further infestation. With chemical control, existing wisteria can be removed mechanically or, if manual removal is impossible.
English Ivy (Hedera helix)
English ivy is an insidious invader, introduced as an ornamental plant in Europe. It is exceptionally hardy, thriving throughout the US. It is found along the entire East coast and has proven to be a severe problem in every state in the Mid-Atlantic. It thrives in both forested and exposed sites and can survive excessive moisture and drought. The plant produces large amounts of berries, which can be dispersed by birds carrying them to new locations. It threatens ecosystems by forming dense monocultures, carpeting trees, and the ground and can suffocate and smother plants. Ivy is best controlled by pulling or applications of thick layers of mulch, which can smother ivy growing on the ground. Herbicide may be needed for larger or older infestations with deeper roots.
Japanese Honeysuckle (Lonicera japonica)
Japanese honeysuckle is an attractive vine that has a serious dark side. It has become popular in the horticultural industry due to the pretty flowers and lovely fragrance. Still, it easily escapes cultivation and invades natural areas to smother other plants and decrease ecosystem diversity. Therefore, it is best controlled with repeated moving and mechanical destruction followed by herbicide application to the remaining stumps and foliage.
Kudzu (Pueraria montana var. lobata)
Introduced as erosion control, animal feed, and garden plant, kudzu has become known as the ‘plant that ate the south’ due to the intensity at which it has invaded southern states. What many do not know, however, is that kudzu has successfully established populations throughout the US and can be found in many counties in the Mid-Atlantic. Kudzu causes damage by smothering trees, causing them to fall, climb powerlines and damage them through sheer weight. It can also cause soil erosion and alter the nutrient balance of invaded forests. However, kudzu can be controlled with grazing, manual removal, and targeted herbicide application.
Mile-a-Minute (Persicaria perfoliata)
Known for its long, barbed vines and ability to smother and topple other plants, the mile-a-minute weed is a serious invader that is in the process of expanding its range further into North America. It is found in all Mid-Atlantic states, where it grows into a dense, tangled carpet of vines that can engulf whole trees. As a result, the plants they grow on can become starved for light and often die, posing a severe danger to native ecosystems and horticultural crops. Trees can even fall over due to the sheer weight of the vines. The best control method is a species of weevil, introduced as a biocontrol agent, consuming the plant and thus suppressing mile-a-minute populations.