We have seen instances where Palmer amaranth will continue to emerge in early to mid-fall, respond to the short days and immediately set seed. In addition, marestail will start emerging during the same period,” says Bob Bruss, Ph.D. and director of technical services for Nufarm Americas. To deal with the problem, Bruss recommends a broad-spectrum residual herbicide paired with a burndown product such as 2,4-D. See this white paper to learn more specifics on fall burndown.