What do consumers really know about the chemical composition of the wetting agents they purchase? An acknowledged expert in the field asks, ‘Does it matter?’
Dr Karnock emerges from the rhizotron at the University of Georgia, where wetting agent research is carried out. Photo courtesy of the University of Georgia.
At the 2013 Golf Industry Show (GIS) in San Diego, a superintendent asked me which wetting agent chemistry was best. He then began to rattle off long, impressive, chemical names such as “alkyl polyglucosides,” “polyoxyethylene,” “super-blocked end polymers,” etc. My response was a polite but straightforward, “Who cares?”
Of course we should all be concerned about the chemicals we use in terms of the environment and health, but here I am discussing the chemistry of wetting agents in terms of the mode of action and/or the performance of the product. The only question should be, “Does the product perform as the manufacturer claims?” The individual was obviously surprised by my response.
Here I would like to explain why I believe too much attention is being paid to the advertised chemistries of wetting agents.
‘Old’ vs ‘new’ chemistry
It has become quite common over the past several years for some companies and individuals to refer to wetting agents as having “old” or “new” chemistry. The implication (intended or not) is that the old chemistries are inferior to the new ones.
I don’t believe any chemistry or product in any area of our lives should automatically be considered outdated or inferior simply because of age. In fact, some of the older chemistries that are still being used today in turfgrass management are among our most reliable. Take, for instance, 2,4-D (commercially released in 1946) and carbaryl (Sevin, released in 1958). Consider chemicals such as copper sulfate (1760) or sulfur dust (1824) that have been used as fungicides. Or one of the most widely used turf fungicides today, chlorothalonil, which was first registered in 1966. The fact that these chemistries have been around so long is a testament to their effectiveness and value to turfgrass managers.
Suggesting that wetting agents can be separated in terms of performance on the basis of the age of their chemistry is misleading at best. In fact, speaking from 30 years of working with wetting agents, I know of several “old” chemistry wetting agents that are every bit as effective as those with “new” chemistry. The effectiveness of the chemistry depends on several factors such as the degree of soil water repellency or even the amount of soil organic matter. Less derogatory terminology might be “earlier” or “previous” chemistries.
Localized dry spot is not uniformly distributed throughout greens and generally occurs where turf is undergoing the most stress. Photo by F. Wong.
Are superintendents enamored with wetting agent chemistry?
The superintendent I spoke to at the GIS was not the first to raise the issue with me. I receive phone calls, emails and questions during my wetting agent lectures asking about their chemistries. I began to wonder how widespread this interest was.
With the help of the GCSAA education staff, a pre-seminar questionnaire was sent to 257 registrants in my 4 GIS seminars that year. One of the questions was, “How important is knowing the chemical composition of a wetting agent you are about to purchase?” The choices were (a) very important, (b) somewhat important, (c) not important. Although this was far from a scientific poll, I simply wanted some feel for the significance of this issue. Was it something that needed to be discussed during my seminars?
There were 129 replies to this particular question. 48% of respondents indicated that it was very important, while 50% indicated it was somewhat important and 2% said it was not important. Thus, 98%
of respondents believe that knowing the chemical composition of a wetting agent holds some level of importance. I had to ask myself, “Why?”
Wetting agent classification systems?
Answers to other questions on the questionnaire indicated that a chemical classification system published by some wetting agent companies may have had some influence on their purchasing decisions. For clarification, these classifications are based on the known or suspected chemistries of certain wetting agents, and the published charts usually provide the mode of action or performance characteristics for each class of chemistries listed. The intention of such classification is to provide the turfgrass manager with a guide to the expected performance of a wetting agent. In other words, knowing the chemical properties
of a wetting agent should assist a turfgrass manager in selecting the wetting agent that best fits his or her needs.
Classification systems are usually developed by scientific or professional associations, societies or committees. To my knowledge, no such group has developed one for turfgrass wetting agents. One reason such an official system does not exist is that it is nearly impossible to know the exact chemical makeup of a wetting agent without reverse chemical engineering of each one or without each company revealing the chemical makeup of their products.
A look at the labels of the wetting agents on the market today shows that companies are not forthcoming in providing this information. The exact chemistry of these products is considered proprietary information. Keep in mind that wetting agents — unlike most other chemicals used in turfgrass management — are not regulated by US state or federal governments, with the exception of a few states where registration is required. What about the unofficial turfgrass wetting agent classifications often seen today? Are such systems valid? Can they provide turfgrass managers a guide to the proper selection of a wetting agent?
To answer that question, let’s look at one classification system, using the results of the Wetting Agent Evaluation Study funded by the Environmental Institute for Golf and the United States Golf Association. The study was conducted in 2003 and 2004 and the results were published in Golf Course Management in April and August 2005.
In this study, 10 wetting agents were evaluated at 9 locations throughout the country. Exactly the same testing procedures were used at each location. Of the 10 wetting agents, 9 (Aquaduct, Brilliance, Cascade Plus, Hydro-Wet, LescoFlo, Naiad, Primer Select, Surfside 37 and Tricure) fit into 5 of the 8 categories of a well-known wetting agent classification system developed by a wetting agent company.
Since these 9 wetting agents are represented in 5 different categories, one would expect distinct differences in performance as suggested by the classification system. Quite the contrary occurred. In general, the results of this nationwide study varied considerably. In some locations, in some years, there were few or no differences found among the 10 wetting agents in terms of phytotoxicity or their effects on soil water repellency (as measured by water-droplet penetration time), regardless of the category of chemistry. In other locations, wetting agents in different classification categories performed the same in terms of both phytotoxicity and reducing soil water repellency. Likewise, wetting agents in the same category sometimes performed differently from each other among locations or even within a location from one year to the next.
There were more similarities than differences among the wetting agents tested. So the questions are: Why so much variation? Why didn’t the wetting agents within the same chemical classification perform similarly throughout all locations or even within the same location from year to year?
There are 2 reasons for the differences. First, the wetting agent classification system does not take into account that companies do not publish the exact chemical makeup of their wetting agents. Although there may be standard chemistries shared by wetting agents that can be grouped or categorized to some extent, many have additional proprietary chemistries that could, in fact, influence performance.
Second, even under strict testing procedures as used in this study, there are variables that will affect performance even more than the unique chemistry of the wetting agent itself.
Wetting agents were tested at the University of Georgia to determine whether they caused phytotoxicity to turfgrass. The variation in color shows the range of phytotoxicity for several different products. Photo by Kevin Tucker
Variables affecting wetting agent performance
What variables can have a greater effect on wetting agent performance than the chemistry itself? Some possibilities are: rates of application, amount of carrier water, amount of irrigation applied after application, time between wetting agent application and irrigation afterward, time of day of application, soil type, degree of soil water repellency, depth of water repellency, amount and types of thatch, mat and/or soil organic matter content, turfgrass species, air temperature, soil temperature, sunlight, etc. These are just the somewhat obvious variables. What about soil pH, water pH, irrigation water quality, formulation, spreader/sprayer calibration and irrigation system uniformity? There are probably many more.
The presence of water-repellent soil can be determined by conducting a water-droplet-penetration time test. If the droplet stays on the surface of the soil core more than 5 seconds, the soil is considered hydrophobic. Photo by Kevin Tucker.
Conclusion
It is recommended that the decision to purchase a particular wetting agent (or any product for that matter) should be based on field performance and not on the purported chemistry and/or claims made about the product. Turf managers should always insist on university test results to support claims and be sure to conduct their own on-site evaluations.
Keith Karnok recently retired from his role a professor in the Department of Crop and Soil Sciences at the University of Georgia, Athens, USA.
This article was first published in Golf Course Management magazine (GCM) in the July 2013 edition. Thanks to Scott Hollister, Editor in Chief, for allowing NZSTI to edit and re-publish this article.
