Knowledgebase

What to do about specific weed type #806061

Asked August 13, 2022, 12:04 PM EDT

Hi, attached are photos of a particular type of weed in my yard. I am unable to identify it when comparing to the weed samples on this website. I’m wondering if I should 1) pull them all out, 2) leave them, will they die over the winter?, or 3) should I spray them, and if so what specifically should I use? This is my first season of lawn care at my home so not sure if these are new or recurring. Thank you.

Hennepin County Minnesota

Expert Response

Are there any hairs on the top pf the leaf?
Pat Mack Replied August 13, 2022, 12:32 PM EDT

Hi, I attached a photo of the very top, not sure if there are “hairs”? Thank you for the quick reply! Deb

Deb Ruen Replied August 13, 2022, 5:08 PM EDT
Dig one  thistle plant out and look at the root system. If it has a taproot then it is a biennial thistle. A biennial thistle die in late summer or early fall after thier seeds have matured. Remove and dispose of the seed head.  They all have taproots. You can dig biennial thistle out. ( Dicamba + 2,4-D) or glyphosate are herbicides to use to control Canadian thistles and biennial thistle. You can distinguish Canada thistle from the biennial thistles because it has small flowers (less than 1inch) and smooth stems between the leaves . The biennial thistles all have spiny 'wings' - tissue that looks like a continuation of the leaf - along their stems. Another distinguishing feature is that well-established Canada thistle grows in distinct patches. Apply  herbicide (Dicamba + 2,4-D) or glyphosate to Canadian thistle  in fall when it is recharging its root systemCanada thistle is a perennial  invasive plant that reproduces by creeping,freely sprouting horizontal roots and by seed. It grows in patches because of its root system and perennial nature. The extensive roots are fleshy and send up frequent new shoots. It may require years of frequent mowing and herbicide treatments to kill this invasive weed.
https://extension.umn.edu/identify-invasive-species/canada-thistle  https://www.ag.ndsu.edu/publications/crops/perennial-and-biennial-thistle-control-w799/w-799-perennial-and-bi  https://crops.extension.iastate.edu/encyclopedia/biennial-thistles-iowa

Pat Mack Replied August 13, 2022, 6:02 PM EDT

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