Scouting Michigan fields for Palmer amaranth
Scouting will be key to stopping the spread of glyphosate-resistant Palmer amaranth in Michigan.
It has been almost three years (fall 2010) since Palmer amaranth resistant to glyphosate (Roundup) and ALS-inhibiting herbicides was first reported in Michigan. Initially, populations of this weed appeared to be localized to parts of St. Joseph and Kalamazoo counties. However, last summer more populations of Palmer amaranth were confirmed in nine Michigan counties: St. Joseph, Kalamazoo, Cass, Barry, Ionia, Clinton, Shiawassee, Gratiot, and Livingston. This weed is not native to Michigan and with resistance to glyphosate and other effective herbicides this weed is undoubtedly the toughest that Michigan growers have ever faced. In fact, in many Southern states where this weed is a problem it has been reported that the average increased cost to manage this weed ranges from $30 to $50 more per acre.