Reducing Grain Sorghum (Sorghum bicolor L. Moench) Injury From Postemergence Application of Mesotrione With Dicamba

Weed management in grain sorghum is limited by the number of herbicide options. A two-year (2017-2018) field study was conducted at the Mississippi State University Delta Research and Extension Center, in Stoneville, MS to evaluate the response of grain sorghum to mesotrione application alone or when tank-mixed with dicamba at the two-leaf and four-leaf growth stage of sorghum. Mesotrione was applied at 0.07 and 0.105 kg ai ha-1 alone or was tank-mixed with dicamba at 0.28 kg ae ha-1. Significant injury to grain sorghum from all herbicide treatments was observed compared with the untreated check. Increase in mesotrione application rate increased injury to grain sorghum from 14 to 19% at two-leaf and from 10 to 24% at the four-leaf stage by 4 weeks after application (WAA) in 2017. Adding dicamba to mesotrione reduced grain sorghum injury in both years. At 4-leaf sorghum application stage, mesotrione applied at 0.07 kg ha-1 resulted in greater grain yield than all other herbicide treatments, except mesotrione (0.105 kg ha-1) + NIS in 2017. Our results indicate that adding dicamba to mesotrione safes grain sorghum from injury caused by mesotrione alone.