Our turfgrass science team began wetting agent research in 2014, which led to a 6-year run of multiple projects supported by the Minnesota Golf Course Superintendents Association (MGCSA). During this time, we have looked at many wetting agent products, and tested their many functions and claims. There is still much to learn about wetting agents in turfgrass systems. The benefits described in the marketing claims of wetting agents are not always observed in public research programs. To make matters even more challenging, active ingredients are usually proprietary, and ecological impact information is lacking on safety data sheets, which reduces our ability to develop detailed hypotheses or recommendations. Lastly, there are many factors that likely influence the performance of a wetting agent, so field research won’t always match what golf course superintendents observe on their properties.
One product we included in almost every project was Duplex (Precision Laboratories, LLC, Waukegan, IL). According to Zontek and Kostka (2012), Duplex consists of a straight block copolymer (E/O P/O block copolymer with water-loving portions on each end of the compound). Wetting agents of this chemistry class often claim to improve water infiltration or penetration. A survey of golf course superintendents in Minnesota in 2016 revealed that 15% of the respondents used Duplex on their greens.
Figure 1. Water droplet penetration times (WDPT) at 1 cm depth of each late fall wetting agent treatment and year, averaged across three time points on a USGA research green at St. Paul, MN. Bars that do not share the same letter within year are significantly different.
As part of my M.Sc. thesis research project, I conducted a number of trials on research greens at the UMN Turfgrass Research, Outreach, and Education Center aimed at understanding how temperature might be affecting wetting agent performance. I tested a number of products including Duplex, Cascade Plus, Aquicare, PBS150, and Revolution. In terms of soil water repellency persistence at shallow depths (1 and 2.5 cm), as quantified by the water droplet penetration time (WDPT) test, most products maintained lower soil water repellency than untreated plots for extended periods; however, Duplex did not. More often than not, Duplex applications resulted in similar WDPTs as untreated plots (Figure 1). This was observed on a push-up green and USGA green (Bauer et al., 2017; Schwab, 2020). It is unclear why this is a consistent observation. When this was first observed with a 1 oz 1000 ft-2 rate, which was lesser than other wetting agent products, we bumped it up to a 6 oz 1000 ft-2 rate with similar results. In one project, with a 0.5 oz 1000 ft-2 rate, Duplex-treated plots had the same WDPTs as untreated plots the day after application, and we did water the plots with 1/3 inch immediately after application. Many of the products tested over the years had long-term abilities to prevent localized dry spot, but Duplex did not. Duplex-treated plots often shared similar stress symptoms as untreated plots (Figure 2).
Figure 2. Localized dry spot symptoms on plots of a wetting agent trial in 2017 at St. Paul, MN. This is a single plot example; however, the same trend was observed in other plots and other trials.
So what is going on here? Where did it go? Is it still there? We can’t say for sure. Duplex is advertised as an infiltration surfactant, one that’ll help water move through water repellent regions. It is tough to say if this is actually happening or not without further research. According to the 2016 MGCSA survey, Duplex was within the top 4 most commonly used wetting agents by superintendents in Minnesota, so there are likely many success stories with this product. Not all wetting agents do the same thing or at the same degree. Not all results are similar each year, or at every location. The world of wetting agents is confusing and it’s impossible to gain a full grasp from a handful of research projects using a handful of products.
We would like to thank the MGCSA for supporting our wetting agent research over the years.
Sources
Bauer, S. J., M. J. Cavanaugh, & B. P. Horgan. (2017). Wetting agent influence on putting green surface firmness. International Turfgrass Society Research Journal, 13, 624-628.
Schwab, R. M. (2020). Improving water conservation through wetting agents and unmown roughs. M.S. Thesis, University of Minnesota, Minneapolis, Minnesota.
Zontek, S. J., & S. J. Kostka. (2012). Understanding the different wetting agent chemistries. USGA Green Section Record, 50, 1-6.
