Managing around Waterhemp Resistance

Few weed species have gained so much attention over the past decade as waterhemp. Waterhemp has gone from an obscure weed species in the 1980s to a species that has achieved widespread distinction throughout most of the Midwest. This species gained its notoriety in the early 1990s when it began appearing in many corn and soybean fields in Illinois, Iowa, Kansas, and Missouri. In these fields ALS-inhibiting herbicides, like Pursuit, Classic, Pinnacle, and Beacon were no longer controlling this member of the pigweed family. To make matters worse waterhemp was not a species that most of these producers encountered and in many cases waterhemp identification was confused with the closely related species, redroot pigweed and smooth pigweed. Recently waterhemp has spread throughout most parts of the Midwest, including Wisconsin.