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Invasive Plants in Douglas County

Last week the Minnesota Department of Agriculture confirmed that Palmer Amaranth has been found in Douglas County.  Palmer amaranth is a fast growing weed native to the southwestern United States and northwestern Mexico, and has spread east and north through a variety of pathways including contaminated seed, hay, livestock feed and agricultural equipment. It has developed resistance to multiple classes of herbicides and their different modes of action, making it very difficult and expensive to control. Palmer amaranth is a prolific seed producer; up to 250,000 seeds can come from one plant!  It has a fast growth rate of 2- 3 inches per day and commonly reaches heights of 6- 8 feet, greatly inhibiting crop growth. Reported yield losses have been up to 91% in corn and 79% in soybean in some states. The weed can also significantly increase production costs for corn, soybean, and other crops.

Palmer Amaranth has been classified as a Prohibited Noxious Weed on the Eradicate list by the Minnesota Department of Agriculture.  This legal classification means that all above and below ground parts of the plant must be destroyed. Additionally, no transportation, propagation, or sale of these plants is allowed. Visit for more information on Palmer Amaranth.
Another noxious weed that I have recently had questions about is Common Buckthorn. Common Buckthorn is on the MDAs Restricted Noxious Weed List. Restricted noxious weeds are plants that are widely distributed in Minnesota and are detrimental to human or animal health, the environment, public roads, crops, livestock or other property, but whose only feasible means of control is to prevent their spread by prohibiting the importation, sale, and transportation of their propagating parts. Plants designated as Restricted Noxious Weeds may be reclassified if effective means of control are developed.

Common buckthorn, native to Europe and Asia, is a highly invasive perennial understory shrub or a small tree that can reach heights of 20- 30 feet and 10 inches in diameter. This species was introduced to North America as an ornamental shrub and used for living fence rows and wildlife habitat. Since its introduction, it has spread aggressively across most of the northeast and upper Midwest and has become a serious threat to the degradation of native forest understory habitats where it out-competes native plant species. Common buckthorn infestations form dense, even-aged stands that crowd out native understory species and often completely displace forest understory habitats. These thick infestations also prevent the natural regeneration of forest tree and shrub species. Buckthorn is also a concern to agricultural producers because it can serve as an alternate host for alfalfa mosaic virus, oat crown rust and soybean aphid.

Now is the time to remove buckthorn from your land.  (In November, it’s the only thing green in the landscape!) Visit to learn how to control buckthorn on your property.  A great information source to track invasive species in our area is the Early Detection and Distribution Mapping System (EDDMapS). EDDMapS provides real time tracking of invasive species occurrences, local and national distribution maps, electronic early detection reporting tools and a library of identification and management information. Visit EDDMapS at to keep up to date on the latest invasive species in our area.


Robin Trott
Extension Educator, Horticulture
(320) 762-3890
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