Bayer has reported the discovery of two suspected dicamba-resistant waterhemp populations in Iowa, Iowa State University field agronomist Meaghan Anderson said last week.

This is the first Iowa case of dicamba-resistant waterhemp, belonging to herbicide group (HG) 4, although at least three other states have previously reported similar resistant populations. HG 4-resistant waterhemp was documented by university researchers in Nebraska in 2009, Illinois in 2016 and Missouri in...