Determination of the herbicide resistance status of barnyard grass (Echinochloa crus-galli) weeds collected from paddy fields in different regions of Turkey using a rapid method

The aim of this study was to determine the resistance status of barnyard grass (Echinochloa crus-galli (L.) P. Beauv.), a common weed in Turkish paddy fields, to ALS and ACCase inhibitor herbicides cyhalofop, penoxulam and pinoxaden. The weed populations were collected from 63 paddy fields in the main rice-growing regions of Türkiye, including the Marmara (Balıkesir, Çanakkale, Edirne) and Black Sea (Samsun, Çorum, Sinop) regions. In vitro assays were conducted with herbicide-amended media to evaluate the resistance levels. The results showed that the highest resistance was observed with penoxulam (73.01%), followed by cyhalofop (52.38%) and pinoxaden (46.03%). High-level resistance to all three herbicides was observed at only one location (Edirne/Ipsala/Sarpdere). The highest level of resistance to at least one herbicide was found in Çanakkale (76.16%), followed by Balıkesir (66.67%), Edirne (62.5%), Sinop (50%), Samsun (43.59%) and Çorum (26.67%). This study shows the current resistance status of E. crus-galli populations to common herbicides in different rice-growing areas of Turkey and contributes to the development of effective weed control strategies. In addition, the test method developed in this study can serve as a valuable tool for future research aimed at rapidly and cost-effectively determining herbicide resistance in strategically important weed species infesting different host plants.