Invasive Plants 101: Shrubby honeysuckles

 By Nancy Olmstead

     Shrubby honeysuckles are not only invasive, but large enough to take over a forest understory. Lonicera morrowii, L. tatarica, L. x bella are deciduous shrubs of Northeastern woods, sometimes found around old cellar holes. Older plants have shaggy bark and hollow stem pith; native honeysuckles have solid stems. Leaves are opposite, oval to egg-shaped, with smooth edges, and may be hairy on the bottom. In spring, honeysuckles produce many sweet-scented, yellow or pink flowers in pairs where the leaves meet the stem. Bright red or orange, round fruits develop by late summer.  These are eaten by some birds, though they are low in protein and fats, and are a poor food source.

     Birds disperse shrubby honeysuckle seeds into the forest, however, where they can germinate under the canopy and compete with native trees and shrubs.  Honeysuckles leaf out early, getting a head start on natives, and don’t suffer much insect herbivory. I’ve seen Maine forests where the understory was so choked with large honeysuckles that native saplings were practically absent.  Without control efforts, I worry that these forests will become invasive plant shrublands when the overstory dies or is removed.  

     If you have honeysuckle in your woodlot, there are several ways to get rid of it. Small plants can simply be pulled or dug up. Hang them in a branch to prevent re-rooting, or bag for disposal if fruits are present. Lever-based tools such as the Pullerbear or Uprooter can help for larger shrubs. Larger plants can also be cut; they may re-sprout, so plan to follow up.  Leaving a piece of flagging can help you find the stump again.

      If you wish to use an herbicide, a low concentration of glyphosate (2%) or triclopyr (3-5%), with surfactant, applied to make healthy leaves wet but not dripping, should do the trick as long as you can cover the top of the plant.  Glyphosate is slow-acting. It may be several weeks before you see results; do not cut or remove the plant until it’s dead, to be sure the herbicide kills the roots. Alternatively, you can cut the plant and immediately paint concentrated glyphosate or triclopyr onto the cut area (20-25% solution). Follow all label directions. If you have a large infestation, consider hiring a professional.  

     For more information, visit www.imapinvasives.org/meimi  Nancy Olmstead is an invasive plant biologist with the Maine Natural Areas Program, whose work on invasive plants is supported by the U.S. Environmental Protection Agency, Maine Outdoor Heritage Fund, and USDA’s Natural Resources Conservation Service.