Current status of herbicide resistance in Switzerland

Herbicide resistance is a worldwide industrial agriculture problem that worsens from year to year. In certain northern European countries, black-grass is resistant to numerous different herbicides, and can scarcely be controlled in certain places. This phenomenon is also starting to emerge in Switzerland. Starting in 2011, and in order to monitor the appearance of new resistances and control their spread, Agroscope set up a monitoring programme at national level. This programme is important for the local development of prevention strategies in partnership with the cantonal plant-protection agencies. In Switzerland, the weed species currently affected by resistances are three monocotyledons (black-grass, loose silky bentgrass and Italian ryegrass) and a dicotyledon (lamb’s quarters). These have developed resistances to five different biochemical modes of action, defined at international level by the Herbicide Resistance Action Committee (HRAC). To prevent the appearance of new resistances and to best contain those that have already emerged, it is important to combine both cultural and phytosanitary control methods.