Agronomy and Horticulture, Department of


First Advisor

Christopher Proctor

Second Advisor

Greg Kruger

Date of this Version



Houston B (2022) Water Quality, Carrier Volume and Droplet Size Effects on Herbicide Efficacy and Drift Potential. Theses, Dissertations, and Student Research in Agronomy and Horticulture. University of Nebraska - Lincoln


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Agronomy, Under the Supervision of Professors Christopher Proctor and Greg Kruger. Lincoln, Nebraska: June 2022

Copyright © 2022 Barbara Houston


Herbicide performance is directly related to the amount of active ingredient that has been deposited on the plant. Hence, spray solution characteristics and application parameters are crucial in determining the efficacy of an herbicide application. To maximize the effectiveness of chemical control, methods to deliver full chemical dose must be utilized: allowing the active ingredient to be readily absorbed once added to the carrier and mitigating off-target movement and low herbicide doses. Water is the most frequently used carrier in herbicide applications. Chemical parameters, such as water hardness and pH, can have a critical role in herbicide performance. It is generally believed that weak acid herbicides, such as glyphosate and 2,4-D, have higher dissociation in higher carrier pH, which leads to decreased uptake into plants. Moreover, increased concentration of hard water cations may have antagonistic effect on weak acid herbicide applications. To overcome the negative effect of water quality on weak acid applications, addition of water conditioning adjuvants is recommended. Carrier volume and droplet size are crucial parameters in application technology that can also impact herbicide performance. Nozzles and their spray characteristics have gone under significant development in past decades to enhance spray potential under a wide range of conditions. Introduction of air inclusion nozzles provided the ability to create larger droplets at the same pressure and flow rate as conventional nozzles, resulting in less drift. Controlling off target movement essentialy decreases the potential for herbicide resistance selection on weeds, as well as injury on sensitive crops. Hence, the objectives of this research were to investigate water quality, carrier volume and droplet size effects on herbicide efficacy and drift potential.

Advisors: Christopher Proctor and Greg Kruger