Selecting for triallate resistance in wild oat

Resistance in wild oat (Avena fatua L.) to triallate was monitored from 1996 to 1998 in plots of continuous spring wheat (Triticum aestivum L.) and wheat-fallow, with or without triallate applied from 1979 to 1997. Resistance in wild oat occurred after 18 yr where triallate was applied annually in continuous wheat, but not where triallate was applied 10 times in a wheat-fallow rotation over the same period. No resistance was detected in the continuous wheat or wheat-fallow plots where no herbicide was applied.