Perennial weeds are in a different category than annuals. They don’t just re-seed, they regrow from the ground up, season after season, from root systems that can run three feet deep or spread fifteen feet sideways underground. In this episode, we’re tackling them systematically. First, a regional tour of the most aggressive perennial weeds in the U.S. - what they look like, how they spread, and why they’re so hard to beat.
Then, we work on management using Integrated Pest Management principles, starting with prevention and exclusion, moving through cultural and mechanical controls, and knowing when chemical options are appropriate.
Finally, we close with a hard look at the homemade internet sprays that are all over social media - and why some of them could do more damage to your soil than the weeds ever would.
Let's dig in.
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Montana State University Extension – Field Bindweed (Convolvulus arvensis) MontGuide MT201903AG
https://apps.msuextension.org/montguide/guide.html?sku=MT201903AG
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University of Nevada, Reno Extension – Managing Field Bindweed (Publication 4834)
https://extension.unr.edu/publication.aspx?PubID=4834
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University of Minnesota Extension – Perennial Weeds Identification Guide
https://extension.umn.edu/weed-identification/perennial-weeds
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University of Minnesota Extension – Canada Thistle Identification
https://extension.umn.edu/identify-invasive-species/canada-thistle
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University of Maryland Extension – Canada Thistle
https://extension.umd.edu/resource/canada-thistle
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Colorado State University Extension – Canada Thistle
https://extension.colostate.edu/resource/canada-thistle/
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SARE (Sustainable Agriculture Research & Education) – Canada Thistle: Manage Weeds on Your Farm
https://www.sare.org/publications/manage-weeds-on-your-farm/canada-thistle/
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NC State Extension Plant Toolbox – Sorghum halepense (Johnsongrass)
https://plants.ces.ncsu.edu/plants/sorghum-halepense/
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University of Georgia Extension – Johnsongrass Control in Pastures, Roadsides, and Noncropland Areas
https://fieldreport.caes.uga.edu/?p=62642
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Schantz, M.C. (2025). Johnsongrass (Sorghum halepense): a review of its invasion, management, and spread in the changing climate of the Southern Great Plains. Weed Science, 73(e31), 1–7.
https://doi.org/10.1017/wsc.2025.7
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University of Maryland Extension – Poison Hemlock Identification and Management
https://extension.umd.edu/resource/poison-hemlock-identification-and-management
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Montana State University Extension – Poison Hemlock MontGuide MT200013AG
https://apps.msuextension.org/montguide/guide.html?sku=MT200013AG
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Purdue Extension – Poison Hemlock: Invasive Plant Series (FNR-437-W)
https://www.extension.purdue.edu/extmedia/fnr/fnr-437-w.pdf
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Mississippi State University Extension – Kudzu
https://extension.msstate.edu/publications/kudzu
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Mississippi State University Extension – Torpedograss (Panicum repens)
https://extension.msstate.edu/publications/torpedograss
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UC IPM – Nutsedge (Yellow and Purple)
https://ipm.ucanr.edu/PMG/WEEDS/nutsedge.html
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West Virginia University Extension – Yellow Nutsedge (Cyperus esculentus)
https://extension.wvu.edu/lawn-gardening-pests/weeds/yellow-nutsedge
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Penn State Extension – Japanese and Giant Knotweed
https://extension.psu.edu/japanese-and-giant-knotweed
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University of Wisconsin Extension – Perennial Knotweed Identification (Mark Renz, Extension Weed Scientist)
https://renzweedscience.cals.wisc.edu/wp-content/uploads/sites/177/2025/05/Perennial-knotweed-identification.pdf
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Oregon State University Extension – Solve Pest Problems: Grasses & Grass-Like Pacific Northwest Weeds
https://solvepestproblems.oregonstate.edu/weeds/grass-like
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Washington State University – Perennial Weed Control in the Pacific Northwest (PNW Pest Management Handbooks)
https://pnwhandbooks.org/weed/agronomic/corn/field-silage-seed/perennial-weed-control-quackgrass-field-bindweed-canada-thistle-johnsongrass-etc-0
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Colorado State University Extension – Weed Management (IPM)
https://extension.colostate.edu/resource/weed-management/
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NC State Extension – Extension Gardener Handbook, Chapter 8: Integrated Pest Management
https://content.ces.ncsu.edu/extension-gardener-handbook/8-integrated-pest-management-ipm
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Washington State University – Weed Management (Pesticide Resources and Education Program)
https://pep.wsu.edu/weedmanagement/
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UC IPM – Soil Solarization for Gardens and Landscapes
https://ipm.ucanr.edu/home-and-landscape/soil-solarization-for-gardens-landscapes/
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University of Vermont Extension – Tarping, Solarization and Occultation
https://www.uvm.edu/extension/news/tarping-solarization-and-occultation
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UConn Extension – Homemade Pesticide Issues: Understanding the Science (EXT014, Updated 2024)
https://extension.uconn.edu/publication/homemade-pesticides/
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Ask Extension (Cooperative Extension National Q&A Service) – Vinegar, Salt, and Dawn Weed Killer
https://ask.extension.org/kb/faq.php?id=888177
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University of Florida IFAS Extension – Chapter 4: Integrated Pest Management (Weed Management Categories)
https://edis.ifas.ufl.edu/publication/CV298
