Effect of Florpyrauxifen-benzyl Formulation and Rate for Waterhyacinth Control in a Mesocosm Setting
Abstract Waterhyacinth (Eichhornia crassipes) has been the focus of national legislation efforts and has been listed as noxious, invasive, potentially invasive, or prohibited by at least seven U.S. states. Auxinic herbicides are one of the most effective control methods labeled for use in aquatic sites. In the U.S., florpyrauxifen-benzyl, a synthetic auxin, was recently (2018) registered for use in aquatic sites, but limited information has been published on efficacy, especially differences between the two formulations. Therefore, the purpose of this work was to evaluate two formulations of florpyrauxifen-benzyl – suspension concentrate (SC) and emulsifiable concentrate (EC) – at three rates each (5.9, 11.8, and 23.6 g a.i. ha-1) for control of waterhyacinth under outdoor and greenhouse conditions. All rates of each florpyrauxifen-benzyl formulation reduced waterhyacinth biomass by 90 to 100% when compared to non-treated plants at five weeks after treatment (WAT). Based on plant recovery in the outdoor trial, there was some evidence that the lowest rate (5.9 g a.i. ha-1) of florpyrauxifen-benzyl SC and EC may not be as efficacious at reducing waterhyacinth biomass as the SC and EC formulations when applied at 11.8 and 23.6 g a.i. ha-1. Future work should evaluate the florpyrauxifen-benzyl rates tested in this research against waterhyacinth in field trials and/or an operational setting to confirm findings.