Evaluating long-term and alternative control strategies for waterhemp (amaranthus tuberculatus) management

Waterhemp is a difficult to control weed in the Midwestern United States due to its prevalence in many cropping systems, its high fecundity, rapid growth rate, and evolution of herbicide resistance. Long-term and alternative control methods are vital to understand to allow for continued control of this weed. A long-term study examined the effects of different herbicide programs on the waterhemp soil seedbank, comparing one-pass POST, single residual with two-pass POST, and overlapping residual with two-pass POST programs. Results indicated that including a residual herbicide with a two-pass POST significantly reduced the waterhemp seedbank compared to a single-pass POST alone. Although flumioxazin applied as a PRE resulted in the greatest seedbank reduction, no significant differences were observed between single and overlapping residual applications. Alternative control methods for waterhemp were evaluated in a controlled environment to compare the use of a ground applied allelopathic rice straw mulch to the use of a ground wheat straw mulch. Results indicate that utilizing the allelopathic variety of rice effectively reduced and slowed waterhemp seed emergence when compared to wheat mulch. The results offer information for the long-term impacts of controlling the waterhemp soil seedbank for row crop producers, as well as alternative methods for controlling waterhemp in garden and specialty crop environments.