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.
May 30, 2013
Glyphosate-resistant and some glyphosate- and ALS-resistant horseweed found in Michigan fields: Early management is important
In 2010 two horseweed samples suspected of being resistant to glyphosate were collected from a no-till soybean field and a stale seed-bed sugarbeet field in Ionia and Gratiot counties were confirmed resistant to glyphosate. In 2011 six additional horseweed samples from Lapeer, Clinton, and Washtenaw counties were confirmed resistant to glyphosate and some of these samples are multiple resistant to glyphosate and ALS-inhibitors (FirstRate and Classic), which makes this weed extremely difficult to control in soybean.
April 12, 2012
The drastic swings in temperature over the last several weeks have growers questioning what effect temperature has on weed control from burndown herbicide applications. Several years ago we conducted trials...
April 12, 2012
- 2014 Weed Control Guide for Field Crops (E-434) now available online!
- 2013 Economics of weed control programs for non-GMO soybean are now available
- Information added to "Organic Options" page
- NEW extension bulletins:
- Take Action Herbicide-Resistance Management program
- Final 2013 Weed Control Results are now available for viewing
- 2014 MSU Weed Tour- July 2nd...mark your calendars! Details to come this spring.