 I'm North Dakota Soybean Council Director Rob Rose of Wimbledon. Palmer amaranth, recognized as one of the most aggressive pigweed species, has invaded fields in North Dakota. Palmer amaranth is documented as the most problematic weed in the United States because it grows and reproduces rapidly. It's prone to develop resistance to multiple herbicides. It can also dramatically cut crop yields. The most reliable way to confirm Palmer amaranth is to supplement the visual diagnosis with a DNA test.