A Rapid Bioassay to Detect Trifluralin-Resistant Green Foxtail (Setaria viridis)

In a petri dish assay, radicle growth of trifluralin-resistant (R) green foxtail exposed to trifluralin concentrations of up to 0.4 ppm (w/v) was not inhibited. Radicle growth of trifluralinsusceptible (S) biotypes was completely inhibited. Shoots were more sensitive to trifluralin than roots, with shoot growth being inhibited for both R and S biotypes at trifluralin concentrations of 0.2 ppm or more. Best discrimination between R and S green foxtail biotypes was achieved by measuring radicle length after incubation of pregerminated caryopses at 0.3 ppm trifluralin in the dark for 5 d at 22 C.