Japanese Honeysuckle Lonicera japonica Honeysuckle Family (Caprifoliaceae)
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Department of Environmental Protection
Environmental and Geographic Information Center
79 Elm St., Hartford, CT 06106 (860) 424-3540
Invasive Plant Information Sheet
Japanese
Honeysuckle Lonicera japonica Honeysuckle Family (Caprifoliaceae)
Ecological Impact: Japanese honeysuckle is a rapidly growing woody vine that displaces native vegetation and changes forest structure. The plant spreads vertically and horizontally by climbing up tree trunks and trailing over the forest floor. Trailing vines produce runners that root and give rise to new plants. The vines overtop nearby vegetation and can topple small trees and shrubs by their weight. Dense stands in forest openings exclude most shrubs and herbs. Tree seedlings that penetrate the thick mats are quickly overgrown. Extensive aerial growth produces dense shade and outcompetes with native vegetation for soil moisture and nutrients. Reduced light and nutrients suppress tree growth and inhibit regeneration of woody and herbaceous species. Changing forest structure may impact songbird populations.
Control Methods: The most effective control method for Japanese honeysuckle is to prevent establishment by regularly monitoring for and removing individual plants. Since small plants are difficult to locate, however, plants may easily establish and are then difficult to control. Mowing and burning can help prevent spread, but will not kill the plant. Herbicide use in combination with burning may be the most effective way to control large populations.
Mechanical Control: Small populations can be hand-pulled or removed with a hoe or shovel. Since plants can regenerate from root fragments and branchlets, uprooted plants and trailing vines should be bagged and removed from the area. In old fields and along roadsides, mowing twice a year can slow vegetative spread. However, due to vigorous resprouting, mowing can increase stem density. In fire-adapted plant communities, prescribed burns greatly reduce above-ground growth and limit spread for one or two growing seasons. Burning will not kill most roots, however, and numerous root sprouts can lead to extensive cover within a few years.
Chemical Control: This method is most effective if done in the fall, after the first killing frost and before the first hard frost. At this time, most native species are dormant. Apply a 1.5% solution of glyphosate (e.g., RoundupTM or RodeoTM) and water with a backpack or handheld sprayer. Glyphosate is a non-selective herbicide that will kill all vegetation. Managers should be cautious not to spray so heavily that herbicide drips off the leaves. Herbicide effectiveness can be reduced where large stones or fallen logs protect root crowns. Treated plants should be inspected at the end of the second growing season as plants can recover. Repeated application may be necessary.
Biological Control: Currently, there are no biological control methods available. Insect pests are known from China and the vines are susceptible to honeysuckle latent virus and tobacco leaf curl bigeminivirus transmitted by white flies. However, extensive research is needed before an effective biocontrol program can be established.
October 1999