Amendment of herbicide spray solutions with adjuvants to modify droplet spreading and fading characteristics on weeds

Authors: LIN, JENG-LIANG - National Chiayi University; Zhu, Heping; LING, PETER - The Ohio State University

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2019
Publication Date: 12/1/2019
Citation: Lin, J., Zhu, H., Ling, P. 2019. Amendment of herbicide spray solutions with adjuvants to modify droplet spreading and fading characteristics on weeds. Applied Engineering in Agriculture. 35(5):713-721. https://doi.org/10.13031/aea.13339.
DOI: https://doi.org/10.13031/aea.13339

Interpretive Summary: There are many different types of tough weeds competing with crops for nutrients, space, and water, causing significant economic hurdles in crop production. Applying chemicals is the fastest method to control weed growth. Efficient herbicide applications are often enhanced by addition of adjuvants to spray solutions. However, questions are always raised on how large areas the adjuvant-amended herbicide droplets can cover and how long these droplets can last after they are deposited on the weeds. In this research, the dispersion and fading behaviors of herbicidal droplets amended with three different adjuvants at various concentrations on five different types of weeds were determined. This quantitative information on droplet behaviors on weeds will help formulators compose appropriate active ingredients and additives in herbicide formulations for specific weed control, and will also help spray applicators choose suitable spray agents and nozzles to control specific weeds efficiently and effectively.

Technical Abstract: Herbicidal droplets containing three different adjuvants (Kinetic, DyneAmic, and Preference) deposited on weed leaves were investigated by depositing 300 and 600 µm droplets on five different weed leaves (ragweed, crabgrass, yellow nutsedge, common purslane, and spurge) inside an environment control chamber to characterize the droplet dispersion and fading process. A droplet at a higher relative concentration (RC) of adjuvant had greater possibilities to cover larger areas. In comparison with herbicide-only droplets, Preference-amended droplets had the largest coverage area increase on all of the five tested weeds, and generally followed by droplets with Kinetic and DyneAmic except for 300 µm droplet on purslane and 600 µm droplet on spurge. With addition of adjuvants into herbicidal spray solutions, the 600 µm droplets increased the coverage area by 2.13 to 5.47, 1.76 to 2.56, 1.84 to 2.07, and 2.40 to 4.49 times on crabgrass, yellow nutsedge, common purslane, and spurge respectively, while the 300 µm droplets increased the coverage area on ragweed by 3.88 to 5.86 times. In contrast, fading times of all 300 µm droplets decreased with the adjuvant addition except for DyneAmic applied on purslane. However, fading times of 600 µm droplets did not have increase or decrease trends with adjuvants, which depended on types of the adjuvant and weed. Also, a spray droplet amended with any adjuvant at a higher RC was likely to have a greater integrated index. Appropriate selections of spray adjuvants during herbicide applications could significantly increase droplet deposition effectiveness to facilitate weed control.