Carrier volume and nozzle type effects on spray coverage, droplet density and weed control in peanut

Recent trends in herbicide applications show a preference among peanut growers for using lower carrier volumes and coarser-droplet nozzles. Field-scale studies using commercial application equipment were conducted in 2021 and 2022 to investigate the influence of carrier volume and nozzle type on spray coverage, droplet density, and weed control in peanut. The study treatments consisted of target carrier volumes of 94, 117, and 140 L ha-1, with each volume applied using three different nozzles – XRC, AIXR and TTI – to attain different droplet sizes. Spray coverage and droplet density data were collected during herbicide applications. Weed control was recorded after herbicide applications and peanut yield was measured at harvest. Spray coverage improved with an increase in carrier volume from 94 to 140 L ha-1. The AIXR nozzles provided comparable (2021) or improved (2022) coverage than the XRC nozzle while reduced coverage was observed for the TTI nozzle during both years. Droplet density was greatest for the XRC nozzle followed by the AIXR and TTI nozzles but was not impacted by carrier volume. Despite noticeable differences in spray coverage and/or droplet density, weed control and peanut yield were not affected by carrier volume and nozzle type. Overall, these findings suggest that peanut growers may observe reduced spray coverage for herbicide applications at low carrier volumes and/or when using nozzles that produce large (Ultra Coarse) droplets, but this effect may not directly translate into reduced herbicide efficacy or peanut yield in most fields with low to moderate weed pressure. Future studies should investigate the influence of spray parameters (carrier volume, nozzle type, etc.) on weed management in fields with varying weed pressures and different weed sizes.