Yarrow & tansy - Ask Extension
I've identified an extensive infestation of tansy (pic 1)in my wannabe wildflower field. I believe there is also some type of yarrow (pic 2) that is ...
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Yarrow & tansy #849111
Asked September 08, 2023, 10:48 AM EDT
I've identified an extensive infestation of tansy (pic 1)in my wannabe wildflower field. I believe there is also some type of yarrow (pic 2) that is growing in the field and adjacent lawn as well. I sought advice for tansy control (not eradication) from Chris Gronewald at the DNR whose best suggestions were to cut flowerheads (done) & stems and treat with Escort as glysophates only kill the surface growth. Knowing that an herbicide will also kill my natives, his suggestion was to plant native grasses. Not the most desirable outcome. Suggestions?
Re: yarrow: will pulling spread it? Since my "lawn" has many dandelions that I don't cut until the natives have flowered (so the bees have a spring food), can I judiciously (and successfully) apply a broadleaf herbicide for the yarrow/plantains/chickweed, etc after the dandelions have flowered?
Last pic: hoping this isn't a knapweed. Please help me identify.
Thank you!
Cass County Minnesota
Expert Response
Here is the information on controlling Tansy: https://apps.extension.umn.edu/garden/diagnose/weed/idlist.html#Tansy If you decide to pull it, be sure to wear gloves to prevent irritation of your skin.
Yarrow is actually one of the plants recommended for butterfly gardens. However, if you wish you can pull it. Just make sure to get the entire root.
Your last photo does look like brown knapweed: https://www.minnesotawildflowers.info/flower/brown-knapweed
You can use non-selective herbicides, like Round Up, on any plant without killing all your plants by 'painting' the cut stem with the product. It must be done right after cutting so it is absorbed into the root system.
Yarrow is actually one of the plants recommended for butterfly gardens. However, if you wish you can pull it. Just make sure to get the entire root.
Your last photo does look like brown knapweed: https://www.minnesotawildflowers.info/flower/brown-knapweed
You can use non-selective herbicides, like Round Up, on any plant without killing all your plants by 'painting' the cut stem with the product. It must be done right after cutting so it is absorbed into the root system.
