Take home messages
• Resistance to the Group 22 herbicides paraquat and paraquat + diquat has been found in feathertop Rhodes grass (Chloris virgata) and tall fleabane (Conyza sumatrensis), respectively
• 2,4-D (Group 4) resistance has been found in 5 and 8% of common sowthistle and wild radish populations respectively from the northern cropping region
• Group 22 herbicides are important components of the double knock strategy commonly used for effective control of many northern region weeds. Alternative herbicide options for this use practice are limited
• To manage herbicide resistance, alternative herbicide and non-chemical tactics should be used in combination
