It may not be possible to completely eradicate disease and other threats from golf course greens, but superintendents have a number of available resources to keep them at bay.
Greens are the most precious commodity under a golf course superintendent’s care—but also the area of the course that is most susceptible to damage from funguses, bacteria, and other disease- and weather-related threats. And just like flu viruses, new strains of turf wilt and other agronomic afflictions continue to emerge, just as greenskeepers have learned how to keep the known ones under control.
Changing weather patterns, and how they have affected the character and turf composition of many greens at club and resort properties—often through regrassing projects undertaken to provide better protection against disease threats—are also affecting how those greens are being cultivated, grown in, and then mowed and cared for on an ongoing basis.
And preventive practices employed to deal with these new and more formidable disease threats must now be part of a more environmentally conscious approach to greens cultivation and care—one that uses more natural treatments, with minimal inputs of chemicals and fertilizers
|Summing It Up
• New strains of funguses, bacterial infections and other variations of turf wilt and agronomic afflictions continue to emerge to threaten greens, especially with changing weather conditions and course renovations involving complete grow-ins of new grass varieties.
• The proper diagnosis and correct usage of products and fungicides are vital to battling turf diseases effectively.
• New technological advances such as disease-resistant turfgrasses, improved products, and GPS capabilities can help superintendents treat turf diseases with pinpoint accuracy.
Still, despite the most carefully designed strategies, things do not always go as planned. Whether they are fighting familiar or unfamiliar strains of disease, superintendents often find themselves facing variables that they can’t control. “Football coaches are at the mercy of their players,” says Bill Maynard, CGCS, Director of Golf Course Maintenance Operations at The Country Club of St. Albans (Mo.) and the 2017 President of the Golf Course Superintendents Association of America (GCSAA). “Golf course superintendents are at the mercy of unreliable Mother Nature.”
At St. Albans, Maynard says, the maintenance staff watches out for a broad spectrum of seven to 12 diseases, particularly during the summer when disease pressures are greater on the rough and cool-season grasses. For example, the staff looks for dollar spot on its bentgrass greens, and rust in the fescue rough. Greens in the transition zone are also prone to wilt- or patch-type diseases, Maynard notes.
Cool-season turf in the fairways or rough is more susceptible to disease pressures in the transition zone, he adds, while warm-season grasses, such as zoysia, are less susceptible to disease in that region.
Grasses, especially on newly planted greens, are also more prone to certain diseases within the first 12 to 18 months of the grow-in period. “There’s a type of Pythium disease that happens about a year after newly seeded greens have been established,” Maynard notes.
Rust begins with yellow spotting on blades of grass before it spreads and darkens over time to the hue that gives the disease its name. Based on its severity, Maynard says, the staff might not treat it. Fine, dark-colored grasses such as fine fescue, ryegrass, and bluegrass are more susceptible to rust than other grasses, and it is most severe in turf that is growing slowly because of adverse weather conditions. Drought and infrequent mowing encourage rust to develop as well.
Spotting New Threats
Bentgrasses in the North and Bermudagrasses in the South both see primarily fungal diseases, notes Megan Kennelly, a Professor in Kansas State University’s Department of Plant Pathology.
Sometimes, however, a property encounters an unfamiliar disease. In 2007, on golf courses in metropolitan Houston as well as in Mississippi, Alabama, and Tennessee, large areas of sunken spots, ranging in color from dark-chocolate brown to black, first began to appear, after periods of high precipitation, on short-cut, highly maintained Bermuda and zoysia grasses. As the disease progressed, according to a published paper co-authored by Young-Ki Jo, an Associate Professor and Extension Specialist at Texas A&M University, the spots grew into larger, mushy irregular patches of blighted leaves on the warm-season turfgrasses.
Jo and Mississippi State University’s Maria Tomaso-Peterson independently started examining a pathogen on samples of infected grasses from various golf courses. After comparing their findings, they realized that the pathogen was unknown to scientists. Through lab tests and DNA sequence comparisons, they found that the pathogen was a new species of fungal disease, which they named Curvularia malina. Among superintendents, however, the disease is more commonly called “ink spot.”
“In some cases, the leaves can be wilted and turn black,” says Jo. “It damages the leaf, but usually, the root is OK. The black spot also causes uneven growth, and reduces the aesthetics and playability of the golf course.”
Erasing the Evidence
One of the golf courses where ink spot appeared was the all-zoysia, 18-hole Tom Fazio Championship Course at The Club at Carlton Woods, a 36-hole property in The Woodlands, Texas.
“It’s not really a detrimental disease. It doesn’t kill the turf, but it’s unsightly,” says Carlton Woods’ Golf Course Superintendent, Tim Huber, CGCS, who started working at the Fazio course in 2010. “It affects aesthetics by causing blemishes.”
Because Carlton Woods’ golf course, which opened in 2006, has only zoysia grass, he adds, the entire course was susceptible to the disease. In this case, he says, the rough, which has different types of zoysia, was not affected by ink spot, which appeared primarily on the fairways.
“It may infect tall grasses or low-maintenance turf, but it may not be as noticeable,” Jo reveals. “It was more noticeable in the short-cut fairway.”
According to Jo, the disease, which is caused by a fungus, starts to show up in the late spring or summer. From his experience, Huber has found that ink spot is brought on when wet conditions follow periods of drought.
“Soil moisture is important; soil-moisture levels are related to the disease,” Jo adds. “If it’s not properly managed or goes without any fungicide applications, it will continue into the fall. And if you don’t control it, it spreads.”
The Club at Carlton Woods grounds crew also scouts for other diseases such as large patch, leaf spot, dollar spot, Pythium on the greens, and pest infestations.
While zoysia is a little more prone to fungus than Bermudagrass, Huber says, he was attracted to the Fazio course because of its all-zoysia turf. He calls it “a grass of the future” that new properties, particularly in the South and in the transition zone, will use because it provides a good playing surface in the winter and requires fewer inputs such as fertility and insecticide applications. In addition, the grass does not need to be mowed as frequently.
Superintendents in different parts of the country deal with different disease pressures, Huber notes. He previously worked on bentgrass and bluegrass courses in Ohio, where he worried about different issues than those he encounters on zoysia grass in Texas.
“You get dialed into what you’re going to see,” he explains. “As a property ages, you see a higher population of insects or disease pressures. A 100-year-old course in the Northeast with a hodgepodge of old soils and old grasses will face more difficult situations. It can be unpredictable, but everything is controlled.”
Superintendents can combat disease by following best-management practices, which vary from region to region, Maynard says. In addition, he notes, “Turfgrass breeders are creating more environmentally friendly varieties that are resistant to certain diseases through their genetic makeups.”
High-density bentgrass varieties, such as A-4 or 007, are more appealing than intermediate-density varieties, Maynard adds, because they have greater disease resistance and heat tolerance, and require fewer chemical inputs.
Other advances in the turf industry can help superintendents control disease as well. “The advances in sprayer technology have given us the ability to reduce overall inputs with the use of GPS technology,” Maynard notes.
GPS also gives pesticide applicators the ability to apply treatments with pinpoint accuracy. In addition, current technology allows applicators to turn on only the valve that is needed, Maynard reports, allowing properties to save on pesticide usage and costs.
“All applications are applied by state-licensed pesticide applicators at below-label rates,” he adds. “When we use technology to our advantage, we make applications only at certain thresholds, and not just when something starts.”
In addition, notes Huber, it’s important to keep golf course maintenance “in the hands of professional superintendents who follow the law and the labels.”
Manufacturing companies are also constantly developing new products that have years of research behind them, and offer classes about their product usage to superintendents.
When superintendents use preventive measures and treat their turf culturally, states Maynard, they can reduce disease pressure by having a healthy soil environment. “Early prevention is key,” he emphasizes.
Keeping a Constant Watch
Despite all of the new technological tools that are now available, Maynard notes, one of the most effective ways to defend the turf remains scouting it for disease. Superintendents can also use online tools to track “growing-degree days”—heat units that have accumulated and are needed for plant growth and development. Monitoring growing-degree days helps superintendents effectively time herbicide and plant growth-regulator applications, as well as increase weed control.
While preventive measures typically are more effective than curative approaches, notes Maynard, he might make a curative application at a rate where the plant will not sustain further damage. “You wouldn’t apply inputs unless it was above a threshold level,” Maynard says. “You don’t want turf loss.”
Ink spot, which possibly is spread by mowing equipment or through aeration, clears up in drier summer weather, reports Jo. With field tests, the scientists found a fungicide that can be used preventively or to treat areas that are infected with ink spot. “If we know about the disease, we can control it. We cannot eliminate it,” Jo says.
According to Huber, fertility treatments, applied in conjunction with fungicides, and the use of growth regulators keep the grass from growing too quickly and helps to keep the fungus under control. “Part of our job is to manipulate Mother Nature and make grass do things it doesn’t normally do,” he says. “If you know what triggers a disease, you can stay ahead of it. Now that we know the treatments for [ink spot], we can home in on it.”
The Club at Carlton Woods has gone from making applications to combat ink spot on all acreage to spot-treatment of the disease, which saves time, money and product. And while Huber also feels that preventive measures are generally more effective than curative treatments to battle turf diseases, he will sometimes wait to see how severe a developing disease may become before treating it.
“If we get dollar spot in the rough, we’ll let it go unless it gets too unsightly,” he explains. “The push to use fewer inputs is economical and ecological.
“Using fewer inputs is good because it helps recalibrate people’s eyes from perfect, unblemished conditions,” Huber adds. “Play it as you find it. That’s better from a golf purist’s standpoint.”
Weathering Uncontrollable Variables
Uncontrollable variables—namely, the whims of Mother Nature—can exacerbate disease pressures as well. According to Maynard, extreme weather patterns can increase disease susceptibility and make recovery more difficult.
For instance, he explains, “High daytime temperatures with average night temperatures above 78 degrees increase disease severity. Recovery is almost impossible, because the plant can’t respirate and grow outside a certain temperature range. The plant is just trying to survive.”
High temperatures followed by heavy rainfalls increases disease pressures even further, Maynard adds. “Wet soil heats up much faster than dry soil, and it takes soil-moisture management out of the superintendent’s hands and in uncontrollable Mother Nature’s hands,” he says. “That makes a stressful job even more stressful.”
The primary grasses used on Gulf Coast golf courses— Bermudagrass and zoysia grass—are suitable to areas that experience hot summers, Jo notes. However, he says, environmental conditions in the region are conducive to disease development, largely because of the frequency and the amount of precipitation.
Last year, The Club at Carlton Woods experienced extreme weather patterns, including a 100-year flood in April, which overran six holes and damaged the bunkers, followed by another 100-year flood in May, which left 11 holes underwater for 48 hours.
“With that comes the spread of weed seeds and things that come in off the property that we fight so hard against,” Huber says.
In Kansas last summer, golf courses experienced high humidity and drenching rains that compromised the health of root systems and made plants more susceptible to diseases such as root rot. Plants are like people, Kennelly notes, in that they “are more prone to disease when they’re stressed.”
However, she says, superintendents are familiar with the weather patterns that lead to certain diseases, so they can look ahead to weather forecasts to prepare for the threats that may arise from upcoming conditions.
Counting on Camaraderie
In addition to weather forecasts, superintendents have other resources at their disposal to help them battle disease. They can read trade magazines, take advantage of the extensive resources offered by the GCSAA and its regional chapters, or turn to other superintendents, local distributors, and university-extension specialists for their expertise.
“We can recommend products that work best for them in their region,” Kennelly says. “We know what works best in our region, and we can calibrate it to other weather conditions. A lot of us have blogs and Twitter where we will let superintendents know about disease conditions we’re starting to see, so they can be on their radar.”
Some extension specialists even make house calls. Jo came to The Club at Carlton Woods about once a week during the summer for several years to study ink spot. He set up formal research plots on the eighth fairway and the driving range to chart weather patterns, moisture, and rainfall. He experimented with fertilizer rates and various treatments, making more findings each year.
The club’s grounds crew members set up no-maintenance buffer zones around the plots, so they would not interfere with Jo’s research. He also did large patch studies for the golf course in the fall, and Huber credits the membership for allowing research to be conducted on the golf course.
“We had first-hand, site-specific experience,” he states. ‘‘We didn’t have to conduct research on our own, and it was a huge savings for the property.” Without Jo’s help with the ink-spot issues, he adds, it would have taken the staff much longer to figure out a solution to the problem.
Superintendents rely on their colleagues—and perhaps a small dose of pride—to keep their turf healthy as well.
“The business is so competitive,” says Huber. “Superintendents want their golf courses to be better than others, but it’s definitely a business that has good camaraderie. The golf business is not an easy business. Superintendents have a hard job, but they’re willing to help out the next guy.”
Maynard agrees. “Our association is a brotherhood,” he adds. “We borrow equipment, exchange trade secrets, and participate in each other’s well-being.”