Selective Doses of Mesotrione Applied at Different Post-Emergence Stages of White Oat (Avena sativa) Cultivated in Southern Plateau of Brazil

This study aimed to characterize the selectivity of the herbicide mesotrione, applied at three different stages of plant development, by evaluating the injury, yield and quality of grains of white oats. The experimental design was completely randomized with four replicates. The plants of the white oat cultivar URS Corona were sprayed with 4 doses of mesotrione (0, 84, 168 and 336 g a.i. ha-1) applied at 3 vegetative stages (12, 14 and 16 Zadoks code, as early, ideal and late stages, respectively). Leaf injury began at 7 DAA with the symptoms of leaf bleaching (35% and 10% in the 2022/23 and 2023/24 growing season, respectively) and these injuries were reduced at 28 DAA (5 and 2% in the 2022/23 and 2023/24 season, respectively). The mesotrione sprayed at a dose of 168 g a.i. ha-1, did not cause losses of grain yield and grain quality when compared with the control. In conclusion, mesotrione should be applied at post-emergence up to a dose of 168 g a.i. ha-1 on white oat plants (cv URS Corona) when it had two to six leaves on the main stem. The results showed flexibility and safety regarding the post-emergence application of time and dose of mesotrione on the white oat plants as the selective herbicide.