Herbicide resistance in weeds is a major threat to cost-effective grain production. Understanding the factors that contribute to herbicide resistance is important in developing strategies to delay the onset of resistance.

This project will develop new information on the evolution, inheritance and mechanism of herbicide resistance with a particular focus on the following key existing and emerging resistance issues of importance to growers:

1. glyphosate resistance in brome grass, barnyard grass, sow-thistle and prickly lettuce;

2. clethodim resistance in ryegrass; (iii) diflufenican and phenoxy resistance in Indian hedge mustard;

3. 2,4-D resistance in sow-thistle;

4. triallate and prosulfocarb resistance in annual ryegrass; and

5. propyzamide and trifluralin resistance in annual ryegrass.

Outcomes from the research will be delivered to farm advisers and growers to encourage better stewardship of key herbicides.