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The arrival of summer and the accompanying heat and humidity means increased stress on golf courses and heightened concerns for those caring for them.

Golf Course Industry reached out to turf professionals for their insights on combating and overcoming summer stress issues.

Build a good foundation

Having a sound agronomic program in place at, or even before, the start off the season will help minimize problems when the weather warms up.

Elliott Dowling is a USGA Green Section agronomist covering the Northeast Region. He stresses the importance of fortifying turf against summer heat and humidity, a process that ideally should begin months before the onset of warm weather.

“One of the many goals of the fall cultivation season is to recover grass from the summer stress it might have had,” he says, “and also get it as healthy as it can possibly be going into the winter where the grass, at least in the Northern states, will either go dormant or just virtually shut down growth. In the Southern states, it’s a little different. But when grass isn’t growing and not recovering, there isn’t anything you can do.”

Dowling notes that making a preemptive effort to strengthen the plant against the summer heat will minimize problems later. “The healthier the plants are going into the most stressful months, usually the better prepared they are,” he says. “Not that they’re immune or won’t have a disease outbreak eventually. But plant health going into and really through the duration (of the summer) is very important to outcompete some of the heat and humidity we’re going to see.”

Troy Fink is the director of agronomy at Blessings Golf Club outside Fayetteville, Arkansas. “Just have a good, sound agronomic program where your fertility is dialed in to grow healthy grass but still maintain playability,” he says.

Fink has a preventative fungicide schedule in place. At trouble spots, specifically difficult green complexes, he and his team will utilize fans to increase air movement.

Product usage

Opinions varied among the experts Golf Course Industry spoke with as to whether to adjust intervals or application rates during the heat of the summer.

John Ballard is the superintendent at Valhalla Golf Club in Louisville, Kentucky. He’s preparing to host the PGA Championship in 2024, which will be contested in May in a Transition Zone growing environment. Ballard has plenty of experience handling the region’s turf stresses, having spent more than 20 years as a superintendent in the Louisville area.

“I think more than anything we look at tightening up those intervals a little bit,” he says. “Let’s just say our interval might be a two-week, 14-day kind of thing; we might adjust that and get as tight as every seven days. I think lighter rates, more frequently during the summer, whatever you’re doing, seem to work well for us.”

Fink utilizes a different approach at his club. “If the label says seven to 14 days, generally, we’re going 14 days,” he says. “But if it says the range is two to four ounces, we would go with the four-ounce rate (at 14 days). If the product says it will 21 to 28 days for the most part, we’ll carry it out through the 28th day.”

Kyle Callahan is in charge of caring for the turf at Thornblade Club, a private facility in Greer, South Carolina, less than 20 miles from Greenville. Callahan adjusts his rotation in deference to the hot summer weather.

“From past experience we tend to stay away from nitrates and nitrites,” he says. “At some point, the nitrogen will convert over, but we do our best to read the labels and avoid those products. Typically, we use more raw materials so we can control exactly what we want in the tanks. Another area we adjust in the heat and humidity that has given us success is ensuring that our foliar tanks have aminos and phosphites in the tank along with fungicides that have technology for plant health. In our soil sprays, we try to ensure our tanks have a good food source for microorganisms and add products that will increase our microorganism population for a healthy root zone.”

Rolling vs. mowing

Should superintendents roll or mow in hot, humid weather? The experts we spoke with say “Do both.”

Dr. Adam Thoms is an assistant professor at Iowa State University with a specialty in commercial turfgrass management. “I’m a believer in mowing and rolling at least every other day,” he says. “Or maybe, during the heat of the summer, skipping the mowing and just rolling that day. That kind of relieves some of that summer stress.”

Callahan is of the same mindset. “We believe there needs to be a balance of both for consistent playing conditions and overall turf health,” he says. “Some days, we will do both based on playability, events and turf health. Other days we will skip a mow or roll depending on how the turf is responding and the forecast.”

Ballard also believes in both mowing and rolling but fine-tunes his approach in some circumstances — specifically, if he’s preparing for a major event. “Let’s say we’re trying to achieve specific green speeds for events,” he says. “(What we do) is a mow and just a target roll, just target-roll where the hole location is for the day.

“Instead of putting a little added stress on the entire green, we’re just doing it on a third of that green and the golfer really can’t really tell because it’s that last foot or two that rolls out to the hole that matters, not 50 feet away.”

Soil management

When the topic is soil management, Ballard’s thoughts turn to water management.

“I think water management is key,” he says. “We’re trying to make sure we’re not keeping those profiles too saturated. And then we really try to do a lot of venting, is what a lot of guys will call it, (utilizing) little solid pencil tines. We’re just trying to open things up a little bit, get some gas exchange and cool (the soil) down a little bit in that fashion.”

Ballard embraces the concept of venting putting greens in hot, humid weather.

“We might start on the golf course late in the evening, around 6 or 7 at night and knock out six or seven holes,” he says, “and then again first thing in the morning, starting around 6 a.m. and finishing the balance, so we’re not (working) in the heat of the day. We’ve opened them up, we’ve let them breathe for a day and then kind of roll them back out.”

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Soil nutrients

As is the case with other products, the nutrient protocol at a particular facility may vary considerably from that of its neighbor down the street.

“We’ll take our soil samples in the wintertime,” Fink says, “and we’ll look at the levels, especially phosphorous and potassium and look at those levels, the pH, and then if any adjustments need to be made. If something is getting low in phosphorus or low on potassium, we’ll try to make those supplemental applications in the spring of the year so that the plant has the whole year to use it. And then the same thing along the lines of pH and any other nutrients that may look like they’re out of balance. But generally, it would be the exception as far as having to do something.”

Fink says he does not test regularly for the nitrogen level in the soil. “Its level in the soil and the plant can change,” he says. “It can change in a short amount of time. So, taking a soil test, you wouldn’t be able to rely on that information. It changes too quickly.”

Thoms points out there can be too much of a good thing. “You still need to keep your nutrition program, your greens fed,” he says. “But you don’t want to overfeed them by any means. You want to make sure that they are getting just the right amount of nutrition. Too much, obviously, is going to create succulent growth, so that’s going to create conditions for disease. I like to say that they need to be a little lean going into the stress time.”

The power of technology

How does today’s technology aid turf professionals in their ongoing efforts to provide quality playing conditions?

Fink utilizes moisture meters at his facility but says the data they provide should be interpreted differently from one golf course to another. “You just kind of learn what’s right for your greens,” he says. “Say our greens here are at 15 percent. You go down the street, 15 percent may not mean the same thing in regards to whether (the greens) need water or not. A Stimpmeter is more transferrable from course to course.”

Callahan notes that moisture meters, drones and digital technology have an upside. But he offers a caveat. “I think they play a role in our program,” he says “and help our team communicate on an even playing field, i.e. sharing an average number on a moisture meter that will relate to someone across the course. For me, personally, I have found myself converting back a little bit to an “old school” approach of using a knife, soil probe and my eyes to manage the turfgrass. There is enough data and information out there to skew BMP for turfgrass.”

Rick Woelfel is a Philadelphia-based writer and a frequent Golf Course Industry contributor.