Mesocosm studies were conducted in 2020 to evaluate the effects of carrier volume and application method on waterhyacinth response to 2,4-D, glyphosate, and diquat. Carrier volumes of 935, 467, and 187 L ha-1 were applied using either a conventional stream, conventional cone, adjustable cone, or a drizzle stream spray pattern. Reducing carrier volume from 935 L ha-1 reduced spray coverage up to 60% depending on application method. However, reducing carrier volume did not diminish efficacy of any herbicide or application method. Alternatively, waterhyacinth control from 2,4-D increased 10 to 26% when applied using 187 L ha-1 compared to 935 L ha-1. Likewise, waterhyacinth biomass was reduced 91% when 2,4-D was applied using 935 L ha-1; however, treatment applied at 187 L ha-1 resulted in 99% biomass reduction. In general, 2,4-D resulted in roughly 10% greater control when conventional or adjustable cone applications were used compared to either stream applications. Waterhyacinth control 7 days after treatment (DAT) from diquat increased with decreasing carrier volumes; however, treatment effects in diquat experiments were not detected at other evaluation intervals. Glyphosate efficacy was highly influenced by carrier volume as waterhyacinth control increased up to 61% when applied using 187 L ha-1 compared to 935 L ha-1. Moreover, waterhyacinth biomass reduction increased from 55% in 935 L ha-1 treatment to 97% in 187 L ha-1 treatments. Glyphosate application methods consisting of conventional stream or conventional cone sprayers resulted in slightly increased waterhyacinth control by 28 DAT; however, no differences among application methods were observed in waterhyacinth biomass data. These data support further evaluations of alternative application techniques for waterhyacinth control under field conditions as well as other herbicides and aquatic plant species.
Physical–Chemical Properties, Droplet Size, and Efficacy of Dicamba Plus Glyphosate Tank Mixture Influenced by Adjuvants
