By Carl Suk, Land Manager
Of all the exotic invasive plants are the honeysuckles of the genus Lonicera. Bush Honeysuckle is no doubt one of the most troublesome. Honeysuckles belong to the family Caprifoliacea. There are four species of the shrub form and one vine type that are of most concern in Kentucky. The most common of the bush honeysuckles in this area is the Amur Honeysuckle, Lonicera maackii.
Preferring full sun, they tend to favor forest edges, disturbed areas, old agricultural fields, abandoned railroad right of ways and roadside edges. Honeysuckles are extremely adaptable to many different climates and soils, especially calcareous soils. Their vigorous growth can in part be attributed to the lack of natural biological controls such as herbivores, insects and diseases. Eventually they will spread throughout the forest, completely dominating the lower canopy. One study indicated that the rate of spread can be as much as a half-mile per year.
The thick, often impenetrable, cover shades out native species and inhibits forest regeneration. Fortunately, the seeds have low embryo viability and last as little as two years in the seed bank. There has been some evidence of alleopathy which curbs seed germination and seedling growth to some species. In addition, the extensive shallow root system out-competes native flora for nutrients and soil moisture. Not only does honeysuckle reduce forest diversity, but the native plant community has been diminished, causing loss of native habitat and food sources for the forest creatures. The early leaf out and late leaf drop extend the photosynthetic period, contributing to its own growth and decreasing available light to the native plant community.
Studies have shown that this extended foliage time has birds nesting earlier and staying later. Birds also tend to nest lower in the arching branches, which leaves them vulnerable to forest predators. Google “bush honeysuckle” and one will find more information than one needs to know. At the forest, Bush Honeysuckle can be found nearly everywhere.
While the heaviest concentrations are at the most active areas of the forest, one can sporadically find individual plants in even the most remote areas. Birds and small mammals, particularly deer mice, devour the fruits and disperse the seed over a wide area. Humans too are responsible for its spread at the forest as there have been brush piles left along forest roads. Our efforts to remove it are being focused on the area near the Welcome Center, Tom Wallace Park and the Horine Conference Center. The best control procedure is the cut stump method, by cutting the stems close to the ground and painting the stump with an approved herbicide. Removing bush honeysuckle from your property and encouraging others to do likewise will certainly lessen the impact on the environment.