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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Aerial Application Technology Research » Research » Publications at this Location » Publication #349723
Title: Spray droplet size and carrier volume effect on dicamba and glufosinate efficacy

Author
item BUTTS, THOMAS - University Of Nebraska
item SAMPLES, CHASE - University Of Mississippi
item FRANCA, LUCAS - University Of Mississippi
item DODDS, DARRIN - University Of Mississippi
item REYNOLDS, DAN - University Of Mississippi
item ADAMS, JASON - North Dakota State University
item ZOLLINGER, RICHARD - North Dakota State University
item HOWATT, KIRK - North Dakota State University
item Fritz, Bradley - Brad
item Hoffmann, Wesley
item LUCK, JOE - University Of Nebraska
item KRUGER, GREG - University Of Nebraska

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/13/2018
Publication Date: 4/6/2018
Citation: Butts, T., Samples, C., Franca, L., Dodds, D., Reynolds, D., Adams, J., Zollinger, R., Howatt, K., Fritz, B.K., Hoffmann, W.C., Luck, J., Kruger, G. 2018. Spray droplet size and carrier volume effect on dicamba and glufosinate efficacy. Pest Management Science. 74(9):2020-2029. https://doi.org/10.1002/ps.4913.
DOI: https://doi.org/10.1002/ps.4913

Interpretive Summary: Precise applications of pesticides using spray parameters specifically selected to provide optimal efficacy while mitigating off-target movement is critical to the success of American agriculture. Identifying the optimal combination of droplet size and spray rate for a given pesticide and crop pest/disease combinations is key to the success of any application. Multiple combinations of droplet size and application rate were evaluated for two herbicides at multiple locations. Generally, increases in droplet size resulted in decreased efficacy, though an increase in spray rate was found to buffer this effect. Optimal weed control, with minimal drift potential was achieved with coarse spray droplets paired with high application rates. While these results varied somewhat by location, the trends were such that these generalized results are being used to guide site-specific management strategies.

Technical Abstract: BACKGROUND: Pesticide applications using a specific droplet size and carrier volume could maximize herbicide efficacy while mitigating particle drift in a precise and efficient manner. The objectives were to investigate the influence of spray droplet size and carrier volume on dicamba and glufosinate efficacy, and to determine the plausibility of droplet size based site-specific weed management strategies. RESULTS: Generally, across herbicides and carrier volumes, as droplet size increased, weed control decreased. A greater carrier volume (187 L ha-1) buffered this droplet size effect so greater droplet sizes could be used to mitigate drift potential while maintaining sufficient levels of weed control. To mitigate drift potential and achieve satisfactory weed control (=90% of maximum observed control), a 900 µm (Ultra Coarse) droplet size paired with 187 L ha-1 carrier volume is recommended for dicamba applications and a 605 µm (Extremely Coarse) droplet size across carrier volumes is recommended for glufosinate applications. Although general droplet size recommendations were created, optimum droplet sizes for weed control varied significantly across site-years. CONCLUSION: Convoluted interactions occur between droplet size, carrier volume, and other application parameters. Recommendations for optimizing herbicide applications based on droplet size should be based on a site-specific management approach to better account for these interactions.