Cumulative Map of Herbicide Resistant Weeds In Michigan

In 1980, common lambsquarters was the first weed to be confirmed resistant to the triazine herbicides (Group 5) in Huron County, Michigan by Ph.D. student E. Patrick Fuerst and Professor Donald Penner. Over the years following a few more weeds were confirmed resistant by MSU weed scientists Donald Penner, Jim Kells, Karen Renner, and Bernard Zandstra. In 2000, Steve Gower began a more formalized screening program through MSU Diagnostic Services. In 2010 the screenings were moved to the laboratory of Christy Sprague and in 2015 they returned to Diagnostic Services under the direction of Erin Hill. The current screening process, supported largely by the Michigan Soybean Promotion Committee, involves greenhouse bioassays started from weed seeds harvested from escaped weeds. Each weed is screened against five to six different sites of action in an effort to detect new incidents of resistance and cases of multiple resistance.





Herbicide Resistance Encountered In Macomb, MI Herbicide Resistance Encountered In Isabella County Herbicide Resistance Encountered in Shiawassee County Herbicide Resistance Encountered In MIchigan Herbicide Resistance Encountered in Ingham County Herbicide Resistance Encountered In Oakland, MI Herbicide Resistance Encountered In Wayne, MI Herbicide Resistance Encountered in St. Clair County, MI Herbicide Resistance Encountered In Washtenaw County, MI Herbicide Resistance Encountered in Lenawee County, MI Herbicide Resistance Encountered in Monroe County, MI Herbicide Resistance Encountered In Hillsdale County, MI Herbicide Resistance Encountered in Branch County, MI Herbicide Resistance Encountered In St. Joseph County, MI Herbicide Resistance Encountered in Cass County, MI Herbicide Resistance Encountered in Berrien County, MI Herbicide Resistance Encountered In Allegan County, MI Herbicide Resistance Encountered In Barry County, MI Herbicide Resistance Encountered In Newaygo County, MI Herbicide Resistance Encountered in Missauke County, MI Herbicide Resistance Encountered In Ionia County, MI Herbicide Resistance Encountered In Montcalm County, MI Herbicide Resistance Encountered In Mason County, MI Herbicide Resistance Encountered in Oceana County, MI Herbicide Resistance Encountered In Tuscola County, MI Herbicide Resistance Encountered in Huron County, Mi Herbicide Resistance Encountered In Lapeer County, MI Resistance Encountered In Saginaw County, MI Herbicide Resistance Encountered in Bay County, MI Herbicide Resistance Cases Found In Manistee County, MI Herbicide Resistance Cases Found In VanBuren County, MI Herbicide Resistance found in Wexford County, MI Herbicide Resistance found In Eaton County, MI

Click on shaded counties to view confirmed cases of herbicide-resistant weeds; the number of resistant species per county is noted. Counties showing no resistance may still have resistant weeds, as samples have not been submitted for all counties. Updated September 2016.


Allegan Co.

  • Common ragweed
    • ALS resistant (2015)
  • Common purslane
    • Triazine resistant (2015)
  • Horseweed (marestail)
    • Triazine resistant (1990s)
  • Palmer amaranth
    • Multiple resistant- ALS & triazine (2015)
    • ALS resistant (2015)

 

Arenac Co.

  • Common ragweed
    • ALS resistant (2015)

 

Barry Co.

  • Palmer amaranth
    • Multiple resistant- ALS, glyphosate, & triazine (2014)
    • Multiple resistant- ALS & glyphosate (2012)
  • Velvetleaf
    • Triazine resistant (2002)

 

Bay Co.

  • Wild carrot
    • Synthetic auxin resistant (1993)

Berrien Co.

  • Common waterhemp
    • Multiple resistant- ALS & glyphosate (2014)
  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2014)

 

Branch Co.

  • Common lambsquarters
    • ALS resistant (2014)
  • Common ragweed
    • ALS resistant (2014)
  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2015)

 

Cass Co.

  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2014)

 

Clinton Co.

  • Common waterhemp
    • ALS resistant (2015)
  • Horseweed (marestail)
    • Glyphosate resistant (2011)
  • Palmer amaranth
    • Multiple resistant- ALS & glyphosate (2012)
  • Prostrate pigweed
    • Uracil resistant (2012)

 

Eaton

  • Horseweed (marestail)
    • Triazine resistant (2001)

 

Gratiot Co.

  • Common lambsquarters
    • ALS resistant (2010)
  • Giant foxtail
    • ALS resistant (2006)
  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2014)
    • ALS resistant (?)
    • Glyphosate resistant (2010)
    • Triazine resistant (2003)
  • Palmer amaranth
    • Multiple resistant- ALS & glyphosate
    • ALS resistant (2012)
    • Glyphosate resistant (2013)

 

Hillsdale Co.

  • Common ragweed
    • ALS resistant (2008)
  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2015)
  • Wild carrot
    • Synthetic auxin resistant (1993)

 

Huron Co.

  • Common lambsquarters
    • Triazine resistant (1980)
  • Common ragweed
    • ALS resistant (2011)
  • Kochia
    • ALS resistant (2004)

    Powell amaranth

    • ALS resistant (2008)

 

 

Ingham Co.

  • Common groundsel
    • Triazine resistant (1990)
  • Horseweed (marestail)
    • ALS resistant (2011)
  • Wild carrot
    • Synthetic auxin resistant (1993)

 

Ionia Co.

  • Common waterhemp
    • ALS resistant (2013)
  • Horseweed (marestail)
    • Glyphosate resistant (2011)

 

Isabella Co.

  • Common ragweed
    • Multiple resistant- ALS & glyphosate (2014)
  • Common waterhemp
    • Multiple resistant- ALS & glyphosate (2011)
  • Horseweed (marestail)
    • ALS resistant (2014)
    • Glyphosate resistant (2011)
  • Powell amaranth
    • ALS resistant (2008)
  • Redroot pigweed
    • ALS resistant (2014)

 

Lapeer Co.

  • Common purslane
    • Multiple resistant- Triazine & ureas/amide (1991)
  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2011)

 

Lenawee Co.

  • Common purslane
    • Multiple resistant- Triazine & ureas/amide (1991)
  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2011)

Macomb Co.

  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2015)

 

Manistee Co.

  • Common lambsquarters
    • Triazine resistant (2006)

 

Mason Co.

  • Common ragweed
    • ALS resistant (2011)
  • Horseweed (marestail)
    • Glyphosate resistant (2007)

 

Missauke Co.

  • Common lambsquarters
    • Triazine resistant (2006)
  • Horseweed (marestail)
    • Triazine resistant (2004)

 

Monroe Co.

  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2013)
    • Glyphosate resistant (2012)

 

Montcalm Co.

  • Common lambsquarters
    • Triazine resistant (2006)
  • Common ragweed
    • ALS resistant (2011)
  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2014)
    • ALS resistant (2011)
    • Glyphosate resistant (2010)
    • Triazine resistant (2004)
  • Powell amaranth
    • Triazine resistant (2006)
  • Velvetleaf
    • Triazine resistant (2004)

 

Newwaygo Co.

  • Powell amaranth
    • ALS resistant (2015)

 

Oakland Co.

  • Common lambsquarters
    • Triazine resistant (2006)
  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2015)

 

Oceana Co.

  • Common ragweed
    • ALS resistant (2013)
  • Horseweed (marestail)
    • ALS resistant (2004)
    • Triazine resistant (2006)
  • Powell amaranth
    • Multiple resistant- Triazine & ureas/amide (1981)
    • Triazine resistant (2006)
  • Redroot pigweed –
    • Multiple resistant- Triazine & ureas/amide (1981)

 

Saginaw Co.

  • Common lambsquarters
    • ALS resistant (2015)
  • Common ragweed
    • Multiple resistant- ALS & glyphosate (2015)
    • ALS resistant (2015)
  • Common waterhemp
    • Multiple resistant- ALS & glyphosate (2014)
    • Multiple resistant- ALS & triazine (2015)
  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2015)
  • Kochia
    • ALS resistant (2005)
  • Powell amaranth
    • ALS resistant (2015)

 

Sanilac Co.

  • Common lambsquarters
    • ALS resistant (2015)
  • Common ragweed
    • Multiple resistant- ALS & glyphosate (2014)
  • Common waterhemp
    • Multiple resistant- ALS & glyphosate (2015)
  • Horseweed (marestail)
    • Glyphosate resistant (2011)
  • Powell amaranth
    • ALS resistant (2015)

 

Shiawassee Co.

  • Common ragweed
    • Multiple resistant- ALS & glyphosate (2014)
  • Common waterhemp
    • Multiple resistant- ALS & glyphosate (2014)
    • ALS resistant (2014)
  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2015)
    • Glyphosate resistant (2013)
  • Palmer amaranth
    • Multiple resistant- ALS & glyphosate (2011)
    • ALS resistant (2014)
  • Powell amaranth
    • Multiple resistant- ALS & triazine (2006)
    • ALS resistant (2011)

 

St. Clair Co.

  • Common waterhemp
    • Multiple resistant- ALS & triazine (2015)
    • ALS resistant (2009)
  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2015)
  • Wild carrot
    • Synthetic auxin resistant (1993)

 

St. Joseph Co.

  • Common waterhemp
    • Multiple resistant- ALS & glyphosate (2014)
  • Palmer amaranth
    • Multiple resistant- ALS & glyphosate (2012)
    • Glyphosate resistant (2010)

 

Tuscola Co.

  • Common waterhemp
    • ALS resistant (2015)

 

Van Buren Co.

  • Common ragweed
    • ALS resistant (2004)
  • Horseweed (marestail)
    • Multiple resistant- ALS & Triazine (2004)
    • ALS resistant (2005)
  • Ladysthumb
    • Triazine resistant (2001)
  • Velvetleaf
    • Triazine resistant (2004)

 

Washtenaw Co.

  • Horseweed (marestail)
    • Multiple resistant- ALS & glyphosate (2011)
    • Glyphosate resistant (2011)

 

Wayne Co.

  • Common waterhemp
    • Multiple resistant- ALS & glyphosate (2015)

 

Wexford Co.

  • Horseweed (marestail)
    • Triazine resistant (2006)

 

Other Confirmed Cases from Unknown Michigan Counties

  • Common ragweed
    • Triazine resistant (1990)
  • Eastern black nightshade
    • Triazine resistant (2004)
  • Halberdleaf orach
    • Triazine resistant (2003)
  • Lateflowering goosefoot
    • Triazine resistant (2004)
  • Marestail
    • Multiple resistant- Triazine & ureas/amide (2002)
    • Ureas/amide resistant (2002)
  • Smooth pigweed
    • ALS resistant (2002)