I have had many questions regarding waterhemp control this year as many farmers are seeing poor results from the use of glyphosate and/or ALS herbicides.

Common waterhemp is documented in Iowa as having resistance to three sites of action, which include ALS inhibitors, HPPD inhibitors and EPSPS inhibitors (glycine).

Marestail is also becoming a concern in Iowa, and now palmer amaranth has been documented in Harrison County.

Most herbicides are not registered past flowering, or...