Development of herbicides resistance in Apera spica-venti in Lithuania

For decades, farmers have been increasingly reliant on herbicides for effective weed management.Repetitive longterm application of herbicides with the same mode of action has resulted in the evolution of herbicide resistance woldwide.The crops most affected by weed resistance in Europe are winter cereals, and one of the worst weeds is silky bent grass (Apera spica-venti (L.) P. Beauv.).Seeds of A. spica-venti were collected from across Lithuania from the farmer's fields, where this weed was not controlled despite herbicide application.A total of 159 populations of A. spica-venti were tested in greenhause studies over the period of 2016-2018.In the experiments, the resistance of A. spica-venti to the following herbicides was assessed: methyliodosulphuron natrium, sulphosulphuron and pyroxsulam (aceto-lactate synthase (ALS) inhibitors), fenoxaprop-P-ethyl and pinoxaden (acetyl-coenzyme A carboxylase (ACCase) inhibitors) and isoproturon (photosystem II (PSII) inhibitor).It was found that of the 159 seed samples tested, 43% showed little response to ALS inhibitors, sulphosulphuron, methyliodosulphuron and pyroxulam.Most of the tested populations were resistant to sulphosulphuron, while the fewest populations were resistant to pyroxulam, but all populations resistant to pyroxulam were resistant to both other ALS inhibitors, methyliodosulphuron natrium and sulphosulphuron.Growing resistance of A. spica-venti to ALS inhibitors will greatly restrict the choice of herbicides currently available for weed control in spring; therefore, autumn herbicide application in winter cereals in the future can become very important, especially in the fields, where A. spica-venti is highly distributed.