Case 3: Target Site Resistance (TSR) to ACCase Inhibitors: Pinoxaden (Axial® 50) and Cycloxydim (Focus® Ultra)
The tested plants show a variation in the ACCase gene: Ile-to-Leu at position 1781. This variant leads to target site resistance against all ACCase inhibitors (HRAC 1).
Consequences:
- Both Axial® 50 and Focus® Ultra are ineffective.
- There are no effective post-emergence products available for oilseed rape (exception: partial efficacy of Select 240 EC).
Strategy:
Absolute priority: Avoid the use of HRAC-1 herbicides to prevent further selection pressure. Strategically, only HRAC-2 herbicides can be used to suppress target site resistance. In wheat: Broadway® or AVOXA, in maize: MaisTer® power. It is crucial to prevent the selection of metabolic resistance to ALS inhibitors in cereals.
The problem crops here are oilseed rape and barley.
