Not to be confused with Missouri’s native vine honeysuckles, invasive bush honeysuckles such as Morrow’s and Amur are shrubby natives of Asia. Here in the United States, where they have no natural controls, they leaf out in April, grow fast, spread fast and form dense thickets that crowd out Missouri’s native forest plants. If you’ve got a giant green thicket in your woods, you may have a bush honeysuckle infestation.
Bush honeysuckle leaves appear early in the spring and remain late into fall, giving them a competitive advantage over native plants. They form a thick understory that limits sunlight to native plants inhibiting seedling establishment and forest regeneration. They also compete for soil moisture, nutrients, and may produce a chemical that inhibits native plant growth. All species of honeysuckle also spread from the roots, resulting in the ability to further dominate an area. Bush honeysuckles compete with native plants for pollinators, resulting in fewer seeds set on native species. Unlike native shrubs, the fruits of exotic bush honeysuckles are carbohydrate-rich and do not provide migrating birds with the high-fat content needed for long flights.
Effects on Natural Communities
Bush honeysuckles will invade a wide variety of natural communities with or without previous disturbances. Affected natural communities can include: lake and stream banks, marsh, fens, sedge meadow, wet and dry prairies, savannas, floodplain and upland forests and woodlands.
Control measures may enlist one or more of the following techniques: prescribed burning, hand pulling of seedlings, cutting and herbicide treatments. A recently introduced pest, the European Honeysuckle aphid, somewhat controls flower and fruit production in some of the bush honeysuckles. Heavy infestations cause tips of branches to form “witches’ brooms” or deformed twigs. This often greatly reduces fruit production. Native ladybug beetles, however, have been noted to control this aphid.
In fire-adapted communities, spring prescribed burning will kill seedlings and kill the tops of mature plants. Bush honeysuckles readily re-sprout and repeated fires are necessary for adequate control. It may be necessary to burn annually or biennially for five years or more for effective control.
Seedlings may be hand-pulled when soils are moist. All of the root should be removed or re-sprouting will occur. Physical removal by hand-pulling smaller plants or grubbing out large plants should not be used in sensitive habitats. Open soil and remaining root stocks will result in rapid re-invasion or re-sprouting of honeysuckles and other exotic species.
Bush honeysuckle stems can be cut at the base with brush-cutters, chainsaws or hand tools. After cutting, a 20-percent solution of glyphosate should be applied to the cut stump either by spraying the stump with a low pressure hand-held sprayer or wiping the herbicide on the stump with a sponge applicator to prevent re-sprouting. Glyphosate is available under the trade names Roundup and Rodeo, products manufactured by Monsanto. While the Roundup and Rodeo labels recommend a 50- to 100-percent concentration of herbicide for stump treatment, a 20-percent concentration of Roundup has proven effective (Note: some products containing glyphosate or another herbicide may be pre-diluted, so be sure to read product labels to understand herbicide concentration levels). It is not known if this lesser concentration is effective for Rodeo also. Rodeo can be used in wetlands and over open water, but Roundup is only labeled for use in non-wetlands. Herbicides should be applied to the cut stump immediately after cutting for best results. Application in late summer, early fall or the dormant season has proven effective. Some re-sprouting may occur with a follow up treatment being necessary. Glyphosate is non-selective, so care should be taken to avoid contacting non-target plants. The wood of bush honeysuckles is very tough and easily dulls power tool blades. Underplanting of native species following honeysuckle removal may be necessary to reestablish a desirable composition of ground cover, shrubs and understory trees. This may also minimize the risk of reinvasion by bush honeysuckles and other exotic species.
Information sourced from the Missouri Department of Conservation.