Selecting for triallate resistance in wild oat

Resistance in wild oat (Avena fatua L.) to triallate was monitored from 199 6 to 1998 in plots of continuous spring wheat (Triticum aestivum L.) and wh eat-fallow, with or without triallate applied from 1979 to 1997. Resistance in wild oat occurred after 18 yr where triallate was applied annually in c ontinuous wheat, but not where triallate was applied 10 times in a wheat-fa llow rotation over the same period. No resistance was detected in the conti nuous wheat or wheat-fallow plots where no herbicide was applied.