WORTHINGTON — During these hot and humid dog days of summer, one can step outside and smell the corn growing in nearby fields. Take a drive down a country road and you will see towering corn crops, canopied soybean plants, and acre upon acre of alfalfa and grassland being mowed and baled for livestock.
What you might also see are road ditches and fence lines filling in with colorful blooms of wildflowers — though not all of them are a welcome sight for those tasked with maintenance. In fact, what some may view as a flower, others see as a weed.
Take for instance Queen Anne’s Lace, a delicate-looking flower that can be found in many road ditches around Worthington. Queen Anne’s Lace is also referred to as wild carrot, and is identified on Minnesota’s list of restricted noxious weeds.
According to the Minnesota Department of Agriculture, Queen Anne’s Lace is so widespread in the state that the only feasible means of control is to prevent further spread. Therefore, importing seeds — and selling or transporting propagated plant parts — is prohibited in the state.
While the plant can be detrimental to human or animal health, the environment, public roads and crops, it doesn’t fall into the category of noxious weeds that are prohibited and must be eradicated upon discovery.
In the last five years, Nobles County has had two discoveries on the state’s prohibited/eradicate list — Common Teasel in Elk Township in 2016 and Poison Hemlock in Dewald Township in 2019. In both instances, the discoveries were made in conservation acres, with the invasive seeds unknowingly planted from a conservation mix of seeds.
Nobles County Agriculture Inspector Mitchell Hartwig has, as part of his duties, the role of noxious weed inspector. He said once a discovery of a noxious weed on the state’s eradicate list is made, it must be reported to the Minnesota Department of Agriculture.
Last summer, it was the MDA that told Hartwig of a report of possible poison hemlock. He went to the site to examine the noxious weed and take photos for the state, which then verified it and developed an eradication plan.
The discovery will remain on the state’s database for three years. Monitoring is done during that time to ensure the weed has indeed been eradicated.
There are 16 weed species identified on the prohibited/eradicate list in Minnesota, but one that seems to get the most attention is Palmer Amaranth.
“That’s the big one for local farmers to keep an eye out for and catch before it does take over fields,” Hartwig said, noting that a single Palmer Amaranth plant can produce as many as 250,000 seeds and quickly invade a farm field.
In the far corner of southwest Minnesota, Palmer Amaranth was discovered in Jackson County in 2018. The invasive weed can grow two to three inches per day, and reach heights of six to eight feet. Palmer Amaranth typically blooms between July and November, and has developed herbicide resistance.
“It’s pretty noticeable if you’re seeing it above your corn or beans,” Hartwig said. “I think most guys are kind of checking their fields now. It’s something to keep an eye out for, if they see any type of weed that is unusual or if they’ve not seen before.”
Hartwig said a lot of the complaints he receives about noxious weeds are thistles, which do need to be controlled. Both the Canada Thistle and Plumeless Thistle are on the state’s noxious weed control list. They typically bloom between June and October, and should be cut or mowed at the flower bud stage to prevent seed production.
Hartwig said Nobles County sprays county road ditches to control the weeds, while a lot of the townships mow their road ditches.
For more information on noxious weeds, images and reporting methods, visit mda.state.mn.us/plants-insects/minnesota-noxious-weed-list.