Key Points
In New Zealand, resistance to atrazine has developed in fathen, willow weed and black nightshade. Fathen is also resistant to dicamba. Of major concern is the repeated use of post-emergence herbicides. Strategies to avoid or reduce the risk of resistance include:
- Rotation of herbicides from different chemical groups.
- Use of a combination of two or even three herbicides with different modes of action, but targeting the same weeds.
- Rotating maize with other crops or pasture (more relevant to the maize-silage industry).
- Ensuring sprayers are set up correctly and calibrated so that the active ingredient is delivered more effectively.
- Monitoring paddocks for weed escapes from herbicide application and ensuring these areas do not contain resistant weeds.