Our Winter Woodlands Should Be Brown NOT Green!

December 10, 2016 clifftop CliffNotes

A stark divide between a healthy winter-brown woodland freed from the green invasion of alien bush honeysuckle, and an understory filled with a monoculture of honeysuckle plants. Photo courtesy Joann Fricke, Clifftop.

We’re seeing green: unhappy green, unhealthy green, unfriendly green. We should be seeing brown and we should be seeing brown across vast distances and long viewpoints. IF we were seeing brown now, we could look forward to seeing pinks, blues, yellows, purples in a few months as woodlands blossom with springtime warmth. But our woodlands are choked with still green-leaved bush honeysuckles.

Bush honeysuckle forms understory thickets that shade out and crowd out the natural regeneration of our native plants. Large colonies of bush honeysuckle are easily viewed along Route 3, especially at wooded areas near Columbia and Waterloo, along Bluff Road, and, sadly, at nearly any wooded area. The totality of impact is dramatic, for once a bush honeysuckle thicket has formed, few other plants are able to grow and reproduce. Bush honeysuckle, like many exotic invasive species, creates a monoculture of itself alone, and transforms a landscape into a desert that gives little sustenance to wildlife.

Our native oaks and hickories can no longer generate new seedling growth due to the deep shade. New trees and the future acorn and nut production are therefore reduced.  Deer, turkey, quail and a host of other critters that depend on acorns and nuts for food simply run out of food and, where possible, move on, sometimes to adjacent woods and sometimes into yards and gardens. Native wildflowers are shaded out and, lacking enough sunlight to bloom and set seeds, simply die out. Similarly, our native morels and mushrooms cannot maintain colonies without healthy oak-hickory forest areas on which to spread their spores, and are gone forever. And, as we’ll learn during an upcoming 2017 Clifftop seminar, bush honeysuckle thickets help produce an abundance of ticks, which may transmit disease to both humans and pets.

Bush honeysuckle has taken over much of the woodlands' floor and understory in our area, preventing the regeneration of native oaks and hickories. Photo courtesy Bob Weck, Clifftop.

While the several types of Asian bush honeysuckles present in the U.S. do have differences that separate them into species, all have the same basic story of importation for apparently “good” purposes with unintended and dramatically bad results. Viewed as pretty flowering shrubs, bush honeysuckles were imported first to Europe in 1855 and then introduced to the Eastern U.S. in 1896. Widely sold as ornamental plantings, bush honeysuckles also were recommended for additional seemingly beneficial purposes.  Since deer browse the vegetation and birds and small mammals eat the prolific red berries, bush honeysuckles were viewed as excellent wildlife plantings, and, because the plants form dense colonies due to root suckering, they also were promoted as a way to control soil erosion.

But these two qualities — tremendous seed production and root generation — coupled with a total lack of controlling predators or diseases in U.S. lands, allowed bush honeysuckles to become one of the most invasive plants on our landscape.  As recently as 30 years ago, bush honeysuckles were not known to grow in our area of the state. Time-lapse maps and records of invasive species show a steady and speedy movement of these plants out of urban areas and into all parts of Illinois.

Bush honeysuckle is easily recognized. In fall, its leaves remain green long after native trees and shrubs have dropped their leaves. In spring, bush honeysuckle greens up and leafs out before our native trees and shrubs do. Their ability to green-up earlier and stay green longer gives these invaders an eight to ten week longer growing season: another adaptive advantage which makes bush honeysuckle out-compete our native plants.

Bush honeysuckle is an erect, multi-stemmed semi-evergreen/deciduous shrub with arching branches that can grow 10-20 feet tall. Its leaves are opposite, untoothed, oblong tapering at the tips, and 2-3” long. Fragrant tubular flowers appear in spring and age from white to yellow.

Prolific berry production and its short dormant season help bush honeysuckle out-compete native plants. Photo courtesy Bob Weck, Clifftop.

Bush honeysuckle berries are red, 1/4 inch in diameter, and appear in May-June, staying on the plants into winter. Birds and small mammals eat the berries and help spread the invaders as the seeds are evacuated far from the original plant. Migratory birds, in fact, are the prime culprits in bringing the honeysuckle into our area of the state. The berries, however, are low in fat content compared to our native berry-producing shrubs, and provide low food value to our game and non-game birds.

There is a simple, surefire field test for ensuring you have identified bush honeysuckle and not confused it with one of our beneficial native plants, like deciduous holly. Simply cut off a woody twig or branch with a scissors or a knife. Bush honeysuckle has a hollow pith; our native good guys do not.

There are several management techniques to control and eliminate bush honeysuckle. Smaller specimens, three or less feet high, can be easily pulled by two hands.  Weed-pullers should take care to disturb the soil as little as possible, since seeds may already be present, and, if berries are on the pulled bushes, the pulled plants should be bagged and removed from the area.

Herbicides are effective in controlling bush honeysuckle. Foliar spraying may be the best method for large-scale, heavy infestations. Use a systemic herbicide such as glyphosate (Roundup) or triclopyr (Garlon, Crossbow) in the manufacturer’s recommended dilution strength, adding surfactant if recommended. Thoroughly wet all the honeysuckles’ leaves. This method is most effective in late September through early November.

The downside of this method is potential collateral damage to other desirable plants and contamination of the watershed. Herbicide drift may kill plants close by. If you use too much of the herbicide, the toxins may pass through the honeysuckles’ roots into the roots of nearby desirable non-target native plants. You need to avoid using herbicides near creeks, wetlands, sinkhole ponds, and the watershed in general. And, foliar spraying does not affect any seeds present on the plants. Finally, the foliar spray method uses the largest amount of expensive herbicide.

Nancy and Hannah Weck work to free their woodland of invasive bush honeysuckle. Photo courtesy Bob Weck, Clifftop.

An alternate method to eradicate bush honeysuckle is a combination of manual and chemical practices. It’s also the most work, but will guarantee success with existing colonies of bush honeysuckle.

Simply cut the bush honeysuckle shrubs down to the lowest possible common stem(s) near the ground and then immediately paint, daub or squirt herbicide on the cut stump; make sure to use the dilution strength recommended by the herbicide manufacturer.  Don’t wait to apply the herbicide, because the stump can scab over in less than an hour which prevents herbicide penetration. This method is effective throughout most of the year, but a September – early December timeframe offers greatest herbicide take-up because sap is moving down and will help carry the chemicals to the roots.  Again, if possible, any dead bushes with berries should be carefully removed from the area to prevent seed spread.

Full control and eradication of a bush honeysuckle thicket is a multiyear tasking.  Unfortunately the seeds can remain viable within the soil for several years and, more unfortunately still, seeds from plants in other areas can still be transported into the area you’ve worked so hard to clear of this tenacious invader. But getting your autumn and winter woodlands back to the proper shades of brown will reward you with a healthy landscape and improved wildlife habitat.

CLIFFTOP, a local nonprofit organization, is focused on preserving and protecting area bluff lands.

A version of this article was published in the 18 November edition of the Monroe County Independent.

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