But Hartzler's not convinced the weed will be as difficult to manage as many fear. Farmers who already take a proactive approach to common waterhemp should be able to control Palmer amaranth, as long as they try new strategies, he said.
Given the weed's resistance to glyphosate, which is typically applied after weeds sprout, farmers need pre-emergent herbicides to kill the weed earlier in its growing cycle. Those have a much narrower window of time when they can be applied.
Palmer amaranth likes long growing seasons and hot, sunny weather, Culpepper said, so it may not be quite as aggressive in colder states. However, he said it's still going to be "the baddest boy on the block."