Management of herbicide-resistant grass weeds in Europe

European agricultural methods, based mainly on herbicide weed control, have led to the appearance of 15 herbicide-resistant grass weed biotypes during the period from 1975 to 1995. Target site mutations and enhanced detoxification processes have been characterized as the main mechanisms of resistance. These biotypes are resistant to herbicide families such as PSI and PSII inhibitors, ACCase inhibitors, ALS inhibitors and auxin analogues, some resistant biotypes showing cross- and multiple-resistance. General guidelines to identify and control weed resistance in grass weeds are given. Specific herbicidal control methods which have succeeded in eradicating or at least controlling resistance are suggested for resistant biotypes with mutated target sites. Integrated weed management, including both cultural and chemical methods, is suggested in those cross-resistant biotypes showing enhanced detoxification as a mechanism of tolerance.