[Turfgrass management] Wet the appetite

Wetting agents are the great unknown of golf course chemicals. While their use has increased because they help superintendents control soil moisture better, many in the industry remain confused about when to apply them and what to look for when choosing the right product.

In 1979, there were four wetting-agent manufacturers, and currently, 27 companies offer 75 wetting agents labeled for turfgrass use, according to Keith Karnok, Ph.D., professor of turfgrass science at the University of Georgia. Throughout the past few years, Karnok has surveyed superintendents who have attended his Golf Course Superintendents Association of America seminars. He says 87 percent use wetting agents regularly, and 98 percent use them under certain circumstances.

“Without a doubt, wetting agents have become an important tool for golf course superintendents,” he says.

Superintendents use wetting agents for a variety of reasons, oftentimes to move water deeper into the soil or to retain water near the surface. Surveys show superintendents use wetting agents primarily to control localized dry spots caused by water-repellent soil.

“Research has shown that where soil is water repellent, wetting agents will facilitate more uniform wetting of the soil,” Karnok says. “More uniform wetting results in water savings and more uniform growth of the turfgrass plant, especially the root system.”

Last year, the GCSAA and U.S. Golf Association Green Section released results from a wetting-agent evaluation they sponsored. Ten products were tested at nine sites.

“With so many to choose from, the most common question is: ‘Which one is best?’” says Karnok, who participated in the study. “The evaluation didn’t attempt to answer that question, but it did compare 10 commonly used wetting agents to determine their performance in distinctly different regions of the country because they might perform better in certain situations than others. These differences would be lost if the results from different regions were simply averaged together.”

The study showed there are similarities and definite differences among the products, and it helps explain why a wetting agent might perform differently under diverse conditions, Karnok says. Superintendents should study the information closely and examine the uniqueness of their turf situation.

The complete set of summarized data for all test sites and the entire scientific protocol used to conduct the evaluation is available on the Internet at www.eifg.org.

Big advancement
Wetting agents are one of the biggest advancements in the industry, according to Dan Marco, golf course superintendent at Ruth Lake Country Club in Hinsdale, Ill. Marco has been using them for more than 10 years.

“Over the years, we constantly struggled with localized dry spots, and using wetting agents resolved a lot of our problems,” he says. “Sometimes in summer, we’d have a 3-inch rainfall, and still there would be isolated spots on the course not taking water.”

In the past, Marco used a product early in the year, but found as the end of the season approached it was losing effectiveness and he had to spoon-feed certain areas. Last year he tried a different product and applied it at two-week intervals, beginning in mid-May and continuing through early September.

“We mix the wetting agent with other products such as fungicides and liquid fertilizer and apply it on greens, tees and fairways,” he says. “I’ve also found there are benefits to mixing it with other products that need to be watered in, such as the insecticide we use for grubs.”

But Marco is cautious and says wetting agents can be difficult to select. He always tests small areas before applying them to the entire course.

“We had a dry year last year, and the program we used worked just fine; but who knows if this program would be effective in a wet season?” he says. “There’s always the chance the product could keep the course too wet.”

Treating problem areas
Wetting agents also can help improve problem areas. Kevin A. Bell, superintendent at the 18-hole Marsh Landing Country Club in Ponte Vedra Beach, Fla., experienced problems on greens that had been mended already. In areas with new sod, the sand was different, creating inconsistency throughout the soil profile. Problems were appearing on 12,000 to 14,000 square feet of the 113,000 square feet of greens at the club.

“The greens would be great in the morning and by afternoon they looked like they were suffering from drought,” Bell says. “We needed to keep these areas wet in the top 1 inch, but not sopping wet, which would rot the root zone.”
Bell wanted consistent moisture content in the top 4 inches of the soil profile. His chemical supplier recommended a product, and Bell asked for its university test data.

“That’s the approach I take with most products,” he says. “Universities are more independent, and I like to make sure their data backs up a salesman’s claims.”

Bell was pleased with the results.

“When we apply the wetting agent, we treat the entire green,” he says. “There are always hydrophobic areas we can’t see, and by doing the whole green, we address these spots. We applied this product once a month and in between used a different wetting agent that changes the size of the water molecule so it can get to the thatch layer.”

Different products
Different wetting agents are used for dissimilar growing conditions. These products are proven, through research and field use, to provide superintendents with performance-targeted chemistries that are valuable regardless of rainfall, irrigation water, turf species or climate.

Wetting agents have proven to be effective in four common conditions, according to industry experts. In each case, there might be a specific product that provides the solution.

The first condition involves lower humidity; high winds; maintaining overseeded turf, ultradwarf Bermudagrass, low-cut bentgrass or Poa annua through times of drought; and building soil moisture prior to overseeding.

Specific wetting agents and application regimens might retain moisture in the upper soil profile where the roots are when these conditions exist. They help prevent the top of the soil profile from drying out under higher afternoon temperatures, low humidity and heavy play.

University research trials show how quickly some wetting agents help water to permeate thatch or certain soil types, compared to using water alone. This ensures a rapid, targeted response to turf during periods of stress and often reduces the amount of water needed to satisfy shoot demand. Certain wetting agents require no postapplication irrigation and are convenient to apply without disrupting play.

The second condition involves organic acid production because of organic-matter decay that results in water-repellent soil, water runoff, uneven water penetration, ponding, excessive rainfall creating soggy surfaces, hydrophobicity, drought and signs of stress-related turfgrass diseases.

Specific wetting agents are the first line of defense against a wide range of stressful conditions because they allow water to move faster and deeper into the soil profile for longer periods of time. Certain wetting agents provide improved irrigation efficiency, uniform water infiltration, the ability to rewet hydrophobic soils after periods of drought, and season-long control of localized dry spots. A recent study showed using wetting agents with fungicides against Lycoperdon fairy ring resulted in optimized disease reduction compared to applying the fungicide alone.

In this case, selecting a wetting agent that has the ability to move water into and through the soil profile is important. Applications early in the growing season reduce standing water and promote deeper root systems.

Routine usage throughout hot, dry months delays the onset of symptoms of stress and provides improved turfgrass quality, playability and plant health.
Fall applications ensure better, faster regrowth in the spring and reduced opportunity for winter desiccation.

The result is a year-round tool for superintendents that produces better rooting conditions; more resilient turf; faster rewets; firmer, faster playing surfaces; and significant water savings.

The third condition includes poor water infiltration through thatch, water-repellent soils, layers created by overseeding, and surface water runoff or ponding.

While surfactants reduce the surface tension of water significantly so it penetrates through thatch and into water-repellent soils, reducing puddling and providing faster playability after rain, wetting agents are excellent tools for maintaining soil moisture after overseeding. Some are available in an injectable formulation, making them easy to apply and reducing spray applications. When used as a preventive treatment, they can reduce watering costs.

The fourth condition includes severe topical hydrophobic conditions, necessitating hand-watering and areas of localized dry spot or wilt.

Some wetting agents in tab form are a blend of polymeric surfactants designed to increase water infiltration, improve water retention and provide rescue treatment for localized dry spot. The tabs fit into commercial in-line hose applicators and can be used alone or as part of a comprehensive water-management program.

For each condition, there’s a surfactant with a unique agronomic and performance characteristic. Used in a comprehensive water-management program, wetting agents offer a way for superintendents to ensure year-round, soil-moisture control.

“Of course, whenever possible, do your own testing,” Karnok says. “This is the superintendent’s safest and surest way of increasing the chances for selecting the right product for the right situation.” GCN

David Wolff is a freelance writer based in Watertown, Wis. He can be reached at dgwolff@charter.net.