Mechelle conducts surveys of the WA wheatbelt at harvest by collecting weed seed and screening to a range of herbicides to determine resistance profile. This allows us to assess herbicide resistance levels in cropping fields and monitor change over time for key target weeds species including annual ryegrass, wild oat, wild radish, brome grass and barley grass. Surveys provide base-level resistance data and allow us to monitor change in herbicide resistance frequency over time. It also provides material for further research in understanding herbicide resistance evolution.