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Clark Talks Turf: All things wetting agents

By |  April 7, 2017 0 Comments

Doug Karcher, Ph.D., is a turfgrass scientist at the University of Arkansas. Doug has conducted extensive research and teaches numerous seminars on wetting agents. You may reach Doug at karcher@uark.edu for more information.


Q: Are preventative wetting agent applications more effective in controlling localized dry spot than curative applications?

Preventive applications are more effective controlling localized dry spot (LDS), especially on greens with a history of LDS and greens with slopes, mounds and south exposures that quickly dry out.

Curative applications can work, but usually not before turf quality declines to some extent. If you are in a situation where your only option is a curative application, pay close attention to the greens, and make an application of wetting agent the first day you see LDS appear.

Q: When should a superintendent start making preventive wetting agent applications?

In Arkansas, we typically start in mid-April to mid-May and continue until late September or early October. It’s better to make the first application too early than too late. If you are experiencing a warm, dry winter, a wetting agent application in early spring makes sense, especially if the irrigation system has not been turned on. Except for the cost of the product there is no downside to making a wetting agent application in early spring. If irrigation is not available, try to time the application prior to a rainfall event.

We are conducting an experiment on ultradwarf bermudagrass greens in which we are examining the impact of late fall/early winter wetting agent applications. Our past few winters in Arkansas have been dry, with periodic warm weather — conditions that favor desiccation. Under such conditions, we have seen earlier spring green-up and better turf quality in early spring following a wetting agent application in early December.

Q: Do wetting agents cause more water to be held at the turf/soil surface?

This is the No. 1 concern of superintendents. Many contend that a softer, puffier putting surface sometimes results from wetting agent application. In 10-plus years of research testing a few dozen products, the wetting agent-treated plots never held more moisture at the turf/soil surface than the untreated control. That research used traditional monthly applications in a relatively high spray volume of 2 gal. per 1,000 sq. ft.

We recently initiated an experiment to investigate if application variables might affect surface softness or puffiness. We are comparing wetting agents applied at a full rate every 28 days in a high volume of water versus wetting agents applied at a half rate every 14 days in a low volume of water to compare the label recommendation with the method many superintendents use to apply wetting agents. In one of two years for a couple of tested products we saw a slight increase in moisture at the turf/soil surface. We are trying to determine the importance of these findings.

From late June through August, as day length shortens while temperatures remain high, we frequently observe creeping bentgrass greens becoming puffy, regardless of whether they have been treated with a wetting agent. This is when many superintendents notice more moisture at the soil surface and when many have ramped up their wetting agent program. I think that a lot of the reported puffy/soft surfaces resulting from wetting agent application is more of a correlation based on the time of year rather than a causation effect. If surfaces become soft I strongly urge superintendents who are concerned about this issue to use soil moisture meters and monitor treated and untreated areas to verify whether a wetting agent is the culprit.

Q: Is there anything else you would like to add?

Golf organizations are funding a higher level of university research to better understand many aspects of wetting agents that have not yet been examined. Topics being researched include removal of organic coatings from sand particles, determining if some wetting agents function to move water through the profile and the effectiveness of wetting agents applied in late fall/early winter.

Superintendents need to use a moisture meter if they are dealing with LDS. Wetting agents improve soil moisture uniformity throughout the soil profile. Using a soil moisture meter helps superintendents take advantage of the improved soil moisture uniformity by increasing the time between irrigations or hand-watering.

This is posted in Maintenance, Research

About the Author: Clark Throssell, Ph.D.

Clark Throssell, Ph.D., is the former director of the Purdue University turf program as well as the former director of research for GCSAA. Throssell is the research editor for Golfdom, focusing on managing the Super Science section of the magazine and website. He also contributes his "Clark Talks Turf" column to Golfdom every month.


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