Evaluation of Poa annua L. Resistance to Mitotic Inhibiting Herbicides

Four bioassays were conducted to evaluate an ecotype of Poa annua L. from Chattanooga for resistance to prodiamine, pendimethalin, and dithiopyr herbicides. MSmedia, filter-paper, and soil-based bioassays all evaluated root growth response in mature seed from the Chattanooga ecotype and a sensitive control. The hydroponics bioassay evaluated mature tiller response. All the bioassays were able to diagnose the Chattanooga population as resistant to prodiamine and pendimethalin. The soil-based bioassay was able to detect minimal resistance to dithiopyr. Additionally, the Chattanooga population exhibited variability of resistance to dinitroanalines.