SPECIES CHARACTER
Description
The four species of honeysuckle shrubs planted (Tartarian, Morrow's, Belle and
Amur) that cause the more frequently observed invasive problems will be referred
to as bush honeysuckle. Bush honeysuckles grow to heights of 6-20 feet (1.8-6
meters). They are deciduous, with opposite, entire leaves, and often the older
branches are hollow. Differences between individual species of non-native
honeysuckles are dependent on the presence of pubescence or hair on leaves and
flowers and the length of flowers and their stems. Bush honeysuckles flower
during May and June. Flowers of Tartarian honeysuckle are generally pink, but
may vary from white to bright red. Amur and Morrow's honeysuckle flowers are
white, fading to yellow as they age. Belle honeysuckle is a hybrid cross
between Tartarian and Morrow's honeysuckles and has many characteristics of both
parents. Fruits may be red or yellow and found in pairs in the axils of the
leaves. In addition, there are presently at least 7 other species of bush
honeysuckle or hybrids of these species occurring in Illinois. The best present
key to identify these exotic honeysuckles is Swink and Wilhelm, Flora of the
Chicago Region (1979).
Similar Species
Bush honeysuckles are easily separated from native honeysuckle species by their
stout, erect shrub growth. All native species are "woody twiners" that are
vine-like in nature. Native honeysuckle species are grape honeysuckle (Lonicera
prolifera), yellow honeysuckle (Lonicera flava), and red honeysuckle (Lonicera
dioica). A rule-of-thumb regarding honeysuckles found in Illinois is that all
honeysuckles with a bushy growth form are alien species, no native bush
honeysuckles are known to occur in the State. However, a shrub should be
accurately identified as a bush honeysuckle before attempting any control
measures. If identification of the species is in doubt, the plant's identity
should be confirmed by a knowledgeable individual and/or by consulting
appropriate books.
Distribution
Bush honeysuckles are native to Asia and Western Europe.Ê Tartarian honeysuckle
was introduced to North America in 1752. The other species were introduced in
the late 1800's and 1900's. Although their distribution is closely related to
horticultural outlets, especially near larger urban areas, where used as ornamentals, rural infestations are common when the species are used to improve
wildlife habitat. In Illinois, the northern 2/3 of the state is the prime area
of naturalization, centering around the Chicago region. Some older, localized
outbreaks in southern and central Illinois have been noted. Although not
recorded officially from that many counties, bush honeysuckles are probably now
found in most Illinois counties.
Habitat
Bush honeysuckles have a broad tolerance to a variety of moisture regimes and
habitats. Most natural communities are susceptible to invasion by one or more
of the species. Often the source of the invasion comes from a planting or from
a highly disturbed successional community in which the honeysuckle has
flourished. Wetlands, prairie, and forested communities are all affected.
Habitat disturbance appears to be a key to introduction of these species.
Life History
The spread of bush honeysuckle is generally accomplished by birds. Fruits are
consumed readily upon ripening during summer. Bush honeysuckle plants commonly
are found growing under tall shrubs or trees that act as perch areas for birds.
Seeds appear to need a cold stratification period in order for the seed to break
dormancy. Seedlings establish in areas of sparse herbaceous vegetation and can
tolerate moderate shade. It is suspected that bush honeysuckle may produce
allelopathic chemicals that enter the soil and inhibit the growth of other
plants, preventing native plants from competing with the shrub. Shading by bush
honeysuckle may also limit the growth of native species. Bush honeysuckles leaf
out before many native species and hold their foliage until November.
Effects Upon Natural Areas
Bush honeysuckle will invade a wide variety of native habitats, with or without
any previous disturbances. Although individual species may have certain
environmental tolerances (e.g. Tartarian in drier habitats, Morrow's in moister
areas) at least one of the four types is capable of inhabiting most natural
communities. Affected natural communities include: lake and stream banks,
marsh, fens, sedge meadow, wet and dry prairies, savannas, floodplain and upland
forests.
CONTROL RECOMMENDATIONS
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.
RECOMMENDED PRACTICES IN NATURAL COMMUNITIES OF HIGH QUALITY
In fire-adapted communities, spring prescribed burning will kill seedlings and
kill the tops of mature plants. Bush honeysuckles readily resprout 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 resprouting 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 reinvasion or
resprouting of honeysuckles and other exotics.
Bush honeysuckle stems can be cut at the base with brushcutters, chainsaws or
hand tools. After cutting, a 20% 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
resprouting. Glyphosate is available under the tradenames Roundup and Rodeo,
products manufactured by Monsanto. While the Roundup and Rodeo labels recommend
a 50-100% concentration of herbicide for stump treatment, a 20% concentration of
Roundup has proven effective. 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 labelled for use in non-wetlands. Herbicided 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 resprouting 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 powertool blades.
RECOMMENDED PRACTICES ON BUFFER AND SEVERELY DISTURBED SITES
Methods given above for high-quality natural communities are also effective and
preferred on buffer and disturbed sites. When an area with bush honeysuckle
lacks sufficient fuel to carry a fire, herbicides may be necessary to obtain
control.
In dry, upland areas, a foliar spray of 1% Roundup (glyphosate) will control
seedlings. A 1-1/2% foliar spray of Roundup just after plant blooming in June
will control mature shrubs. Application should occur from late June to just
prior to leaf color changes in fall. The herbicide should be applied while
backing away from from treated areas so as not to walk through the wet
herbicide.
In moist areas, a foliar spray of 1% Rodeo (glyphosate) with Ortho-X27 spreader,
will control seedlings. Application should occur from late June to just prior
to changes in leaf color in the fall. Foliar application of a 1-1/2% solution of
Rodeo (2 oz. Rodeo/galon clean water) will kill mature plants if all foliage is
sprayed. This control method usually requires less labor but more herbicide.
In addition, Krenite controls bush honeysuckle when applied according to label
instructions.
Any treatment should be rechecked in following years for reinvasion. Glyphosate
is a nonselective herbicide and care should be taken to avoid contacting
nontarget plants with herbicide. Do not spray so heavily that herbicide drips
off the target species. By law, herbicides only may be applied according to label instructions and by licensed herbicide applicators or operators when
working on public properties.
FAILED OR INEFFECTIVE PRACTICES
The herbicide Garlon does not control bush honeysuckle.
REFERENCES
Converse, Carmen K. 1984. The Nature Conservancy's Element Stewardship Abstract. Lonicera tatarica, L. morrowii, L. x. bella. 8 pp.
Kline, Virginia. 1981. Control of honeysuckle and buckthorn in oak forests (Wisconsin). Restoration and Management Notes. 1 (1):18.
Todd, Robert. 1985. Honeysuckle controlled by hand pulling (Illinois). Restoration and Management Notes 3 (1):41.
PERSONAL COMMUNICATIONS
Glass, William. 1988. Division of Natural Heritage, Illinois Department of Conservation.
Laurie, Dennis. 1989. Lake County Forest Preserve District, Libertyville, Illinois.
Packard, Steve. 1989. The Nature Conservancy, Chicago, Illinois.
Written for the Illinois Nature Preserves Commission by:
Randy Nyboer
Illinois Department of Conservation
Dearborn Hall
205 E. Seminary Suite
Mt. Carroll, Illinois 61053