I wrote recently about invasive Japanese Honeysuckle, sounding the alarm and passing along some suggestions from ODNR about how to get rid of this pestilence. Since I realized that our farm was being invaded by Japanese Honeysuckle, an aggressive shrub that takes over and smothers everything in its path, we have devoted many days of hard work to beating back this scourge. We’ve tried many different methods, over several years, but our efforts felt like “Whack-A-Mole” as new colonies continued to appear. We have 180 acres, much of it wooded, and we couldn’t seem to turn the tide.
I’m happy to report a breakthrough; a “weapon of mass destruction” we recently tried, that promises to give us the upper hand. This method was suggested to us by ODNR Urban Forester Wendi Van Buren, but we didn’t report in in our earlier column because we hadn’t tried it yet and didn’t realize its potential. It turned out to be so effective that we think we’ll be able to wipe out the existing honeysuckle shrub population on our farm in a matter of days!
The key to success is timing. Japanese honeysuckle is one of the last woody plants to go dormant and drop its leaves in fall, and one of the first to leaf out in spring. This gives us a two to three week window in late fall and early spring when we can spray glyphosate on the invaders with little or no damage to other plants. We prefer fall, because there are wildflowers and other plants in the forest understory that emerge early. For this reason, we’ll limit our glyphosate spraying in spring to the worst infested areas only.
Our weapon of mass destruction is our brand-new Stihl backpack fogger. Similar to a backpack leaf blower, this dandy machine has a 2-1/2 gallon tank and an injector nozzle that mixes glyphosate with a powerful blast of air, creating a fog that can reach plants as far as 20 feet away. The air blast ruffles the leaves, coating both the top and underside of the leaf with a fine mist.
Imagine my elation as I unleashed a glyphosate fog into dense honeysuckle thickets, the wind at my back, hitting the tops of the tallest plants while dousing the carpet of seedlings underneath, as fast as I could walk. We covered many acres along hedgerows and hillsides in a single afternoon. High-fives were in order! Hiking with the backpack sprayer was a workout, soaking us with sweat, but so much faster and easier than any other method we’ve tried by far.
Starting with easily available 44% glyphosate concentrate, we simply measured one cup (16 ounces) into the sprayer tank and topped it off with water. Setting the injector nozzle on 2 seems to give just the right amount of coverage. It takes about fifteen minutes per tankful to empty the tank, at a brisk walk.
A key strategy is to focus on the big, established “mother plants” first, because Japanese honeysuckle can’t reproduce until the plants mature and start to have berries. Birds, attracted by the shiny red berries, spread the invader far and wide. Berries drop under the mature plants and create a carpet of seedlings.
Over the years, readers of this column have admonished us for promoting the use of glyphosate in landscaping, but no one has ever presented us with convincing proof. Experts disagree. For our part, there is a tradeoff between the possible harmful effects of glyphosate and the uncontrolled spread of invasive plants like Japanese honeysuckle, thistle, multiflora rose, poison ivy and autumn olive. An online search turned up no evidence that eating glyphosate-treated berries is harmful to birds, however our approach is to eliminate berry-bearing mature plants first to minimize the risk.
Armed with our newfound “weapon of mass destruction”, we’ll take up the battle again next year. I urge you to join it, in your own yard. Mark your calendar for next November 1, and join us in turning the tide of the honeysuckle invasion.
Steve Boehme is a landscape designer/installer specializing in landscape “makeovers”. “Let’s Grow” is published weekly; column archives are on the “Garden Advice” page at www.goodseedfarm.com. For more information is available at www.goodseedfarm.com or call GoodSeed Farm Landscapes at (937) 587-7021.