Effects and mitigation of poor water quality on herbicide performance: A review

Abstract

Spray water quality parameters such as hardness, pH, alkalinity, turbidity, and total dissolved solids (TDS) can influence the performance of herbicides. Polyvalent cations found in hard water can reduce the efficacy of post‐emergence herbicides that are weak acids. Various approaches have been proposed to mitigate the negative effects of spray water properties on herbicide performance. Water conditioning adjuvants are designed for overcoming the adverse effects of hard water. One group of adjuvants are nitrogen containing compounds such as ammonium sulfate (AMS). The ability of AMS to overcome hard water antagonism is well‐documented but the positive effect of other ammonium compounds are variable and depend on herbicides and weed species. Other adjuvant groups that can overcome effects of poor spray quality are ethoxylated amine surfactants, organic acids and ethylenediaminetetraacetic acid (EDTA). Water quality is poor in many parts of the world, and accordingly, the study of water property effects on herbicide performance is needed to optimize use, and prevent overuse, of herbicides.

Improved control of Taraxacum officinale with 2,4‐D in the field from ammonium sulphate additions

“…Water quality is an often overlooked aspect of herbicide applications that needs careful consideration to achieve successful weed control (Mirzaei et al, 2023). Water is the most common carrier used for spray mixtures and differences in sources (well, surface water, municipal, etc.)…”

“…To reduce hard water antagonism of 2,4-D DMA, the use of ammonium sulphate (Devkota & Johnson, 2016;Patton et al, 2016;Roskamp et al, 2013;Schortgen & Patton, 2020) or urea-ammonium nitrate (Mirzaei et al, 2021;Schortgen & Patton, 2021b) as adjuvants is recommended. See Mirzaei et al (2023) for a review of water hardness and pH and also other water quality parameters (alkalinity, temperature) that influence herbicide efficacy.…”