Integration of sulfonylureas and carfentrazone- ethyl with reduced glyphosate rates for weed management in coffee Integración de sulfonilureas y carfentrazona-etilo con dosis reducidas de glifosato para control de arvenses en café

This study evaluated alternative herbicide strategies to improve broadleaf weed control while reducing glyphosate application rates without compromising coffee productivity. Field experiments were conducted at the Naranjal and Paraguaicito Experimental Stations in Caldas and Quindío, Colombia, using newly established coffee plantations and stump- renewed coffee crops, respectively. Treatments consisted of glyphosate at 720 or 1,080 g a.i. ha-¹ combined with metsulfuron-methyl (15 g a.i. ha-¹), bensulfuron-methyl (50 g a.i. ha-¹), or carfentrazone-ethyl (30 g a.i. ha-¹). These treatments were compared with the commercial glyphosate rate (1,440 g a.i. ha-¹) and manual-mechanical weed control. Five to six herbicide applications were performed over 24 months. Weed cover was assessed between 7 and 63 days after application (DAA), together with coffee phytotoxicity and first-year cherry yield. Glyphosate combined with carfentrazone-ethyl provided rapid and effective weed suppression at 7 and 21 DAA. In contrast, mixtures containing metsulfuron- methyl or bensulfuron-methyl provided superior residual control between 21 and 63 DAA compared with the commercial glyphosate rate. Mild and transient phytotoxicity was observed only in newly established coffee plants treated with metsulfuron-methyl. Importantly, none of the herbicide treatments significantly affected coffee cherry yield. These findings demonstrate that integrating sulfonylureas or carfentrazone-ethyl into weed management programs allows glyphosate rates to be reduced by 25–50% while maintaining effective weed control and crop productivity.