The suitability of microwave technology to provide an alternative to conventional Rumex control in grassland was investigated. For this, two self-propelled microwave devices with respectively 4.8 and 18 kW heat output were tested at different sites and under different weather conditions. The optimal heating times required to obtain a maximal shoot regrowth rate of 20 % were determined in three different variants. Most of the time, the use of microwave technology proved to be helpful in controlling dock plants, but the heating time needed and thus the amount of energy are very high.