Patch work

Patch diseases like summer patch and take-all patch cause headaches for superintendents. Once they appear on the course, it’s tough to get rid of them. But with the right approach, superintendents can minimize the hassle of dealing with them later in the year. Here are four tips to get ahead of patch diseases before they become a problem.

Optimize conditions for root growth

Regardless of the patch disease, prevention is the key, says John Inguagiato, assistant professor of turfgrass pathology at the University of Connecticut, and solid cultural practices are a big part of prevention.

“It’s really important to remember that these are root diseases,” he says. “They’re soil-borne fungi that affect the roots of the turf. If you’re trying to manage these diseases, you’ve got to really optimize conditions for root growth.”

A robust, healthy root system gives turf a better tolerance against threats like take-all patch or summer patch, he says, and early spring and late fall give superintendents opportunities to use cultural practices to get ahead.

“Whenever you have a recurring disease, you always look at the environment,” says Zac Reicher, green solutions specialist for Bayer Environmental Science. “Is it too wet? Is there poor drainage? Is it too hot, or too much compaction? When I get to the point of talking about fungicides, I’m assuming you’ve optimized everything you can in the cultural environment. If you haven’t done that part of it, then the fungicides aren’t going to be very effective.”

One of the major steps a superintendent can take toward good cultural conditions before patch diseases strike are to make sure that there’s minimal compaction, he says. That includes an aggressive aerification program in the spring and fall.

Diseases like summer patch thrive in areas with high foot and cart traffic, like leading onto fairways, says Inguagiato. Core cultivation in those places relieves some of the stress on the turf.

“What’s important is the timing,” he says. “If you go out in late May or even early June, [aerification] can actually be detrimental and enhance the severity of summer patch. That’s just before the heat and stress of the summer.”

With aerification later in the season, the turf won’t get much root growth into the newly opened soil. In fact, it could be damaging what root growth the turf has already developed.

“The take-home message is that cultivation can be beneficial, but it’s important to do it earlier in the season, to really take advantage of the time when soil temperatures are conducive to root growth and build up the root system of the plant and make it more tolerant to infection,” Inguagiato says.

Look for soil temperatures favorable for root growth – around 60 degrees – to maximize the benefits of a spring aerification program before infection occurs, he says.

Use varying depths for repeated solid-tine aerification, however. Going to the same depth over and over can create a hardpan that restricts root growth and penetration, says Inguagiato.

When I get to the point of talking about fungicides, I’m assuming you’ve optimized everything you can in the cultural environment. If you haven’t done that part of it, then the fungicides aren’t going to be very effective.” — Zac Reicher

Thatch control is a more continuous practice, according to Reicher, with topdressing and vertical mowing to keep stress off rootzones.

Using aerification and thatch control to improve turf’s tolerance to disease is common sense, says Kyle Miller, senior technical specialist at BASF. But limiting stress also includes other cultural practices, like mowing at a slightly higher cut.

“Anywhere you’re elevating the stress level of the turf, you’ve got a greater chance for disease to cause damage,” he says. “Mowing very closely is a stress on the plant. Think about making sure you have a good balance there between your playability and your stress level.

“Even raising that mowing height up just a tick can make a huge difference,” he adds. “Then you’ve got a deeper, stronger root system, because you’ve got more turf on the top to photosynthesize carbohydrates and make energy for the plant.”

Get ahead of the infection

One of the reasons that summer patch remains a problem for superintendents is that the symptoms don’t show up until well after the disease has already attacked the turf, says Reicher.

“It starts to attack in the spring, before people are thinking about it,” he says. “The infection usually occurs a month or more before symptoms show up.”

Heat or drought stress can cause the symptoms to show up, says Matt Giese, field technical manager for Syngenta, but by that point prevention isn’t an option any longer. “Fungicide applications should be timed when soil temperatures reach 65 degrees at a 2-inch depth for three to five consecutive days, typically in late spring when the initial infection is occurring,” he says. “In general, two to three applications may be necessary on a 28-day interval or four to six applications of 14-day intervals.”

Similarly, Giese recommends take-all patch applications be timed around soil temperatures in the 50s and low 60s, with two applications in the spring and two in the fall.

Timing for the initial summer patch fungicide applications is critical, says Reicher, and often are done too late to be effective. “Most people wait too long to do it,” he says. “Once temperatures start inching up to 65 degrees, put it down. It’s better to be early than late.”

That first summer patch application can also coincide with a second take-all patch application, says Miller. Fungicide product choice makes a big difference as well, mainly between DMI (such as Mirage, Bayleton or Banner) and QoI products (like Heritage or Insignia).

DMI fungicides offer better control in his opinion, says Reicher, though some superintendents lean away from DMI products during midsummer because of a reputation for causing phytotoxicity or growth regulation.

“But those are still the most effective products, so I’m a big believer in continuing to use DMIs through the summer,” he says. “If you let that summer patch get a hold of your turf, it’s really hard to control.” Reicher suggests a DMI application about every four weeks during the summer, watered in, especially in areas with a history of summer patch.

Equally important for take-all patch and summer patch is following the initial attack (with a 28-day interval between applications) in spring with another one-two combo in the fall, says Miller. Superintendents should set their fungicide programs, especially for diseases that have historically been a problem on the course, and stick to them to stay ahead of the disease before damage can occur.

“The application late in the year, that’s one that’s easy to slip by, because you think, ‘It’s starting to get a little chilly. Soil and air temps are cooling off. I’m not needing to spray as much anymore,’” says Miller. “But you can’t let it slip by.”

Another easy pitfall is to try to just use a higher volume of water with the application to skip the process of watering it into the turf, says Miller. But spreading the application that way won’t allow the product to get down to the roots of the turf.

“It won’t do its job if it can’t get to the disease,” he says. “The turf has a lot of leaves, and they hang up the spray. We want to maximize what we get down to the soil. Water it in.”

Control nutrient inputs

Though it’s tempting to push the turf to get moving with a strong nutrition program as soon as the season starts, it’s safer to hold back a little, especially with nitrogen, says Inguagiato. “One thing they might want to consider is to favor root growth,” he says. “It might be advantageous to avoid excessive nitrogen fertility through those early spring months. You’re absolutely going to get a growth of foliage in the spring, but by applying more nitrogen than is necessary and contributing to more growth, the plant’s growing more foliar tissue at the expense of establishing a good, strong root zone early in the year.”

Being judicious with nitrogen early in the year can promote deeper, healthier roots earlier in the season, which gives turf a better tolerance against summer patch. Using some nitrogen is fine, but when superintendents start seeing excessive clippings, it’s a sign to back off, says Inguagiato.

Maintaining adequate fertility and using slow-release acidifying fertilizers such as ammonium sulfate is believed to reduce summer patch and take-all patch symptoms by lowering soil rhizosphere pH and avoiding rapid lush plant growth, says Giese.

“In addition, research indicates that a two-pound per acre rate of manganese annually in the spring helps reduce summer patch symptoms appearing later in the year,” he says. Manganese sulfate can also limit take-all patch, applied at a rate of eight pounds per acre.

Go to field days

Though it doesn’t immediately improve the turf, one major part of building the right cultivation and fungicide program is attending local field days, says Miller.

“Look at the trials on the particular disease you’re dealing with, and see what’s working in your geography,” he says. “Lean on those products and try them out so you’re giving it the best shot you can.”

The solution doesn’t even have to be the product mentioned at the field day; it could be a change in technique or approach, says Miller. Not only does attending the local field day help support the regional community of superintendents, it gives superintendents the chance to talk about their approach to disease pressure, and how they’re responding to it.

Armed with some new information, a superintendent should take it back to his course and put it to the test. Do trials on your golf course to determine what works under your conditions, Miller says. Take a fairway or green and split it in half, then treat one side with one product or mix, and the other side with another. Collect the data on those results, and start over until the right product or approach is found.

“I just think it’s really important for a superintendent to use his golf course as a research site, instead of relying on universities to do it,” Miller says. “Even though they can give you a lot of good information, at the end of the day, it’s all about your golf course and your conditions.”

Kyle Brown is an Akron, Ohio-based freelance writer and frequent GCI contributor.