By Jennifer Gallus
HOWARD LAKE, MN - An invasive species called common buckthorn is spreading around the Howard Lake and Dutch Lake areas. The corresponding lake associations want to do something about it.
In the coming weeks, lakeshore owners around the two lakes can expect a knock at the door from lake association members who will be asking if the homeowner would like their buckthorn removed, according to Howard Lake Watershed Alliance President Curt Forst.
“We’re going to ask people if they would like us to remove their buckthorn,” Forst explained, “because it’s spreading, it’s undesirable, and it replaces our native, natural plants.”
In fact, common buckthorn is listed as a restricted noxious weed by the Minnesota Department of Agriculture, and the Minnesota Department of Natural Resources (DNR). It is illegal to import, sell, or transport buckthorn in Minnesota.
Buckthorn first appeared in Minnesota in the mid-1800s as European immigrants brought the plant from overseas, and used it as a popular hedging material.
“Shortly after its introduction here,” according to the DNR, “it was found to be invasive in natural areas. The nursery industry stopped selling it in the 1930s, but many buckthorn hedges may still be found in older neighborhoods throughout Minnesota.”
“If buckthorn takes over an area,” Forst explained, “you get mononature. You lose biodiversity. Insects and birds are kind of specific about the foods they like to eat. When you limit the food, you limit the types of insects, which then limits the types of birds in the area.”
“It’s kind of like only having one kind of cereal to eat every morning,” Forst added.
Common buckthorn causes a host of negative environmental impacts including out-competing native plants for nutrients, light, and moisture; degrades wildlife habitat; threatens the future of forests, wetlands, prairies, and other natural habitats; contributes to erosion by shading out other plants that grow on the forest floor; serves as host to other pests such as crown rust fungus and soybean aphid; forms an impenetrable layer of vegetation; and lacks natural controls like insects or disease that would curb its growth, according to the DNR.
“Just like milfoil,” Forst said, “it has a longer growing season. It’s one of the first plants to leaf-out in the spring, and one of the last to lose its leaves in the fall, compared to dogwood or choke cherry.”
Buckthorn can be identified as a shrub having a tall understory or appearing like a small tree up to 25-feet high with a spreading, loosely branched crown, often with multiple stems at the base, according to the DNR.
Leaves are oval in shape with a pointed tip. They are smooth, dark green and glossy. They are also finely toothed and opposite or sub-opposite in arrangement.
The bark is similar to choke cherry, American plum, and other native species, and consequently, it is not recommended that identification be based on bark appearance.
Buckthorn produces large, one-fourth inch round, berry-like clusters of black fruit.
Twigs often end in sharp, stout thorns, according to the DNR.
Control measures for buckthorn largely depend upon the size of the plant. It is always a good idea to call Gopher State One Call at 800-252-1166 before pulling buckthorn from the ground to ensure the absence of buried utilities.
For individual plants, less than three-eighths inch in diameter, the DNR recommends removing by hand. Small seedlings can be pulled and will not resprout.
If the plant is greater than three-eighths inch in diameter, a hand tool is recommended, such as a weed wrench or a root talon.
The DNR also advises that if pulling individual plants is impractical, a herbicide spray such as glyphosate could be considered.
Plants larger than two-inches in diameter are, “best controlled by cutting the stem at the soil surface, and then cover or treat the stump to prevent resprouting,” according to the DNR.
Additional facts, control measures and identification tools can be found at www.mda.state.mn.us/plants/badplants, and at www.dnr.state.mn.us/invasives/terrestrialplants/woody/buckthorn/control.
For those living on the shores of Howard Lake and Dutch Lake, assistance with this invasive plant will be available in the coming weeks.
“It will probably be in mid-October, after the first frost,” Forst said. For more information, Forst can be reached at (320) 543-3736 for questions about the Howard Lake area, and Jamie Wiech can be contacted at (320) 543-3067 regarding the Dutch Lake area.