Published October 19th, 2020
I’ve sounded the alarm about invasive Japanese Honeysuckle, an aggressive shrub that takes over and smothers everything in its path. Under our noses, our woods and stream banks have been taken over, and the bright red berries of mature honeysuckle bushes are being spread everywhere by birds. There are huge, spreading “mother plants” covered with berries, and a carpet of seedlings under them where their berries have fallen.
I’ll bet you have a few in your yard. If you own wooded acreage, I’d be surprised if the same invasion isn’t well advanced on your property. You need to take action and destroy them before your entire landscape turns into a jungle. In doing so you’ll contribute to one of the most important environmental battles of our time. Just ask any urban forester, forest ranger, park manager or conservationist. They’re losing sleep over this problem right now.
Since I first realized that our farm was being invaded by Japanese Honeysuckle, 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.
The key to success is timing. Japanese honeysuckle is one of the last woody plants to go dormant and drop its leaves in fall. This gives us a two-week window in late October and early November when we can spray glyphosate on the invaders with little or no damage to other plants. The plants really stand out right now, because most other woodland plants have lost their leaves. Amur honeysuckle bushes practically glow with neon green foliage and shiny red berries.
Small infestations can be treated with an inexpensive pump sprayer, however we have many acres to deal with. Our weapon of mass destruction is our Stihl backpack fogger, suggested to us by ODNR Urban Forester Wendi Van Buren. 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 15 feet tall and over 30 feet away. The air blast ruffles the leaves, thoroughly coating both the top and underside of the leaf with a fine mist.
We can unleash a glyphosate fog into dense honeysuckle thickets, the wind at our back, hitting the tops of the tallest plants while dousing the carpet of seedlings underneath, as fast as we can walk. We can cover many acres along hedgerows and hillsides in a single afternoon. Hiking with the backpack sprayer is 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 measure two cups (16 ounces) into the sprayer tank and top 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 using 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.
Armed with our newfound “weapon of mass destruction”, we’ll take up the battle again in the coming weeks. I urge you to join it, in your own yard. Mark your calendar, and seize this opportunity to turn the tide of the honeysuckle invasion.