Herbicide resistance in common waterhemp is the most prevalent, and includes resistances to triazines, ALS inhibitors, PPO inhibitors, glyphosate, and HPPD inhibitors. Resistance to HPPD inhibitors is still relatively isolated and uncommon in the state, whereas resistances to herbicides from the other four SOAs are common and widespread throughout much of the state. Numerous waterhemp populations (and even individual plants) possess various combinations of multiple resistances; the current worst-case scenario is resistances to herbicides spanning four SOAs within the same plant. The next most commonly encountered HR weed in Illinois is horseweed. In this species, resistances to glyphosate and ALS inhibitors are thought to be common and widespread throughout Illinois. However, unlike the case with waterhemp, our knowledge of the resistance status in horseweed is based more on anecdotal observations and less on empirical data. Maybe of greatest concern is increasing occurrence of Palmer amaranth populations in Illinois, many of which contain resistances to glyphosate and/or ALS inhibitors.