A Sánchez Ducca1,2, S Sabaté1, MF Barcelló1 and JM Tonatto1,2
1Estación Experimental Agroindustrial Obispo Colombres (EEAOC), Tucumán, Argentina; asanchezducca@eeaoc.org.ar
2Facultad de Agronomía y Zootecnia – UNT, Tucumán, Argentina
Cynodon dactylon is the primary weed in sugarcane cultivation in Tucumán, Argentina, and topramezone, combined with atrazine, is the only registered selective herbicide for post-emergence control of C. dactylon. We aimed to evaluate the herbicidal effect (HE) of tolpyralate alone and in combination with atrazine on C. dactylon. In trials in three years, plants were propagated from stolons and transplanted into field plots to simulate bermudagrass regrowth after mechanical control. Treatments applied to 60-100 cm bermudagrass plants: T1) untreated control; T2) topramezone 33.6 g a.i./ha; T3) topramezone 33.6 g a.i./ha + atrazine 900 g a.i./ha; T4) atrazine 900 g a.i./ha; T5) tolpyralate 40 g a.i./ha; and T6) tolpyralate 40 g a.i./ha + atrazine 900 g a.i./ha. HE was assessed using the ALAM recommended visual scale. Above-ground dry weight (DW) and final green area (FGA) were measured 40 days after application and analyzed using mixed linear models and Fisher’s LSD test (α=0.05). T3 and T6 achieved excellent HE, with the lowest DW and FGA values (9.0 and 9.4 g/plant, 0.01a and 0.02 m², respectively). T2 and T5 achieved good HE, with DW of 70.4 and 61.3 g/plant and FGA of 0.24 and 0.23 m², respectively. Atrazine (T4) showed no HE and did not differ statistically from the untreated control in DW or FGA (319.3 and 501.0 g/plant, 1.20 and 1.72 m², respectively). The effective control of Cynodon dactylon highlights tolpyralate, when combined with atrazine, as a highly promising alternative for post-emergence weed management in sugarcane. This combination not only provides excellent selectivity but also ensures broad-spectrum efficacy, positioning it as a valuable tool in integrated weed management strategies for sugarcane.