MASTER GARDENERS: Hawkweed a very hawkish weed indeed
Have you noticed a yellow or orange bloom on a tall stem that looks like a dandelion on stilts? Many I talk to have noticed this plant in places where they did not appear before. In the woods, along trails, in forage fields, in yards, and especially in ditches and un-maintained properties. I understand why many find the golden or orange fields attractive. You might find yourself humming “Fields of Gold” by Sting.
Called narrow leaf hawkweed or northern hawkweed, its scientific name is Hieracium canadense, but don’t blame the Canadians for this one; it grows all over the world. In Minnesota, it is found everywhere except the southwest part of the state. The Minnesota Department of Natural Resources lists orange hawkweed (Hieracium aurantiacum) as an invasive terrestrial plant. In all, there are more than 50 varieties of the plant.
One of the reasons that hawkweed is so successful at invading new territory is that it spreads by seeds, by runners and by root buds. There is also evidence that it is allopathic, that it chemically suppresses adjacent plants. It is interesting to see how quickly the plant invades new territory.
In Wisconsin, it is listed as a plant that reduces the quality of forage crops while in British Columbia it has become recognized as a serious invasive. In Washington state, hawkweed must be removed from all property. What is ironic is that you can go on Amazon and find more than 20 sources of seed, some describing it as a “spectacular ground cover.” Go figure!
Control of hawkweed can be a tricky business. To get rid of a few plants that have invaded your lawn or garden, digging it up and making sure you get all the root is the most effective method. I have tried mowing it in a road ditch and find that it does not slow it at all. In fact the plant simply shoots up a short bloom stem and goes to seed as well as reproducing more rapidly vegetatively. Seeds are easily transported on the wind and by birds. It colonizes especially well on disturbed sites such as openings created when utility work is done in roadside ditches.
An alternative method of control where it has invaded grassy areas is to fertilize heavily to encourage the grass to grow densely and crowd out the weeds. I have tried flame weeding to no avail. What is left is chemical control with a selective herbicide. In Washington state, their DNR recommends Dicamba with repeat applications. They note that 2,4-D does not provide effective control and glyphosate kills grasses as well and opens the door to re-infestation. Minnesota still recommends that the “most effective control is with Clopyralid or 2,4-D in the rosette stage. A surfactant should be added to the mix to ensure adherence of herbicide to the hairy leaf. These products are dangerous chemicals. Use safety precautions to avoid exposure to yourself, others, pets, wildlife, the surrounding environment or call a certified professional.
The responsibility to deal with invasive and noxious weeds in a safe manner lies with the landowner in Minnesota. The Department of Natural Resources has online guides to help with identification as well as a printed Trail Ambassador’s Guide. For more information, visit www.mndnr.gov/invasives, putting Hieracium aurantiacum in the search box.
Learn to identify the plants you see around you. Many have an interesting history and are very beneficial while some like hawkweed belong on a “wanted” poster.
Click on "Yard and Garden at the University of Minnesota Extension website, www.extension.umn.edu, for gardening information.Local Master Gardeners will respond to your questions via voicemail. Call (218) 444-7916, leaving your name, number and question. Our Facebook page may also be of help to you: www.facebook.com/Beltramicountymastergardeners/.