Decades ago, we lived in the northern Chicago suburbs, where our cozy little neighborhood was called Blueberry Hill because it was built on one of the few inclined bits of ground in a very flat area – and its back yards were thick with trees bursting with deep, blue berries.
We quickly identified that profuse blue-berried vegetation as common buckthorn.
Doug and I bought a chain saw and went after it, but as anyone who has ever battled buckthorn knows – it’s not that easy. The stumps re-sprout vigorously and profusely.
And now you have a spiky thicket – supressing all the native plants beneath it and spreading explosively via birds who eat the attractive, blue berries. The scientific name of buckthorn is Rhamnus cathartica. The “cathartica” part refers to purging. The poor birds are “purging” the berries through their system at high speed as they distribute the seeds along with everything else nutritious they may have eaten before it could be digested.
Well, now there is a new and effective way to clear buckthorn from your property in the places you don’t want to use herbicides. Check out my latest article in Isthmus below.
There’s not a lot to like about the stout, spiked branches of the aggressively invasive buckthorn tree. “Buckthorn is spreading actively across the landscape, facilitated by birds eating the berries and spreading seeds,” says Mark Renz, assistant professor of agronomy at UW-Madison and a UW-Extension weed specialist. “The way it is changing the forest understory is really an epidemic in the upper Midwest.”
Buckthorn was imported from Europe over a century ago as an ornamental hedge. But it began to crowd out native plants in woods and natural areas, and nurseries stopped selling it in the 1930s for the most part. A century later, environmentalists and homeowners are still battling it. Now they have a new weapon — Buckthorn Baggies.
Matthew Hamilton, a UW-Madison senior majoring in mechanical engineering, and the Buckthorn Baggie creator, entered the fray when his dad assigned him backyard buckthorn duty at age 12. “He would have me cut them down every year, and they would just grow back even stronger,” Hamilton says. “By my senior year in high school we were trying to kill them with gasoline and other potent chemicals, which was not good.”
Because buckthorn sends up multiple shoots from each cut stump, foresters have recommended cutting in the fall and treating the stumps immediately with glyphosate, the chemical name for Monsanto’s popular Roundup weed killer. Glyphosate is the most widely used herbicide in the world, but last year, the World Health Organization announced that it is a probable human carcinogen. It is restricted or banned in some countries.
In high school, Hamilton began looking for a nonchemical way to kill buckthorn. He tried attaching bags of different materials, colors, sizes and thicknesses to cut stumps. “We had 30 prototypes that we left on for times ranging from a week to a year, and ultimately, we came up with the Buckthorn Baggie. It has the right properties to completely kill a buckthorn stump when you leave it on for a year.”
The Baggie, covering the stump and held in place with a cable tie, cuts off enough light to prevent the vigorous re-sprouts from growing, starving the tree’s roots and leaving behind one dead buckthorn.
One of the many places in Madison where buckthorns have been doing serious damage is Picnic Point on the UW-Madison campus. Buckthorns quickly grow to 40 feet. They leaf out early and lose their leaves late. Native trees leaf out later, and that used to allow spring wildflowers to thrive on the forest floor. But buckthorn shades out that early spring light.
The leaves buckthorns eventually drop in late fall are very high in nitrogen and decompose much more quickly than the leaves of native trees. That encourages critters in the soil that can take up nitrogen quickly and reproduce rapidly, such as destructive non-native earthworms.