Best Use of Fungicides on Warm-Season Turf

Managing disease on warm-season turf requires prioritization.

Pick a disease to control. Determine the seasons to best handle the pathogens. Select the right fungicide. Let the fungicide’s components do their job.

Using a solution safe to apply year-round such as Navicon® Intrinsic® brand fungicide helps a superintendent prioritize a warm-season turf disease control program. A DMI and strobilurin combination with mefentrifluconazole and pyraclostrobin as active ingredients, Navicon Intrinsic brand fungicide can be applied “any time of the year, any time you have disease, whenever it makes sense to use it,” says BASF senior technical specialist Dr. Emma Lookabaugh.

Summer sprays, Lookabaugh adds, are a necessary — and sometimes overlooked — part of controlling disease on warm-season turf.

“In the past, everybody used to say, ‘You don’t need to spray fungicides in the summer if you’re growing warm-season turfgrass.’ Unfortunately, that’s not the case,” Lookabaugh says. “A lot of these pathogens are most active in the summer and doing quite a bit of damage, and we might not see the damage until the fall, or maybe we don’t see the damage until after winter. However, those pathogens were active a lot earlier, so summer applications are still necessary and needed throughout much of the Southeast.”

Fairy ring, take-all root rot, spring dead spot and large patch are among the diseases Navicon Intrinsic brand fungicide effectively controls on warm-season turf. Lookabaugh calls Navicon Intrinsic brand fungicide a “jack of all trades,” and the utility allows a superintendent to establish disease control priorities.

“It has so many different fits,” Lookabaugh says. “We can use it in the middle of the summer, we can use it in the fall, we can use it as that turf is greening up, and we have no issues. Of all our fungicides, Navicon is probably the most versatile. You can use it so many different ways and it’s effective on many different diseases. And it gives you a DMI in places where historically we have left DMIs out.”

Take fairy ring control, for example.

Soil temperatures above 55 degrees trigger fairy ring, according to Lookabaugh, and the disease potentially requires year-round diligence in lower parts of the United States where warm-season turf covers golf courses. Navicon Intrinsic brand fungicide, along with Maxtima® fungicide, are summer rotational options for courses with extended fairy ring seasons. Navicon Intrinsic brand fungicide is labeled for three applications per year at the high use rate of 0.85 ounces per 1,000 square feet.

“If you have nine months where you have to be making fairy ring applications, then you are definitely going to need a rotation that includes multiple modes of action,” Lookabaugh says. “We like to position Navicon and Maxtima in the warmer months because we don’t see the same growth regulation effects that some other DMIs can cause. So with Navicon and Maxtima you have the opportunity to safely use DMI chemistry in the heat of the summer to control late season fairy ring.”

The versatility of Navicon Intrinsic brand fungicide also expands take-all root rot control options. Take-all root rot occurs on Bermudagrass greens facing the usual suspect of stresses such as low mowing heights, poor drainage, excessive irrigation, poor fertility and abundant thatch. Pathogens are most active, according to Lookabaugh, when soil temperatures hover between 77 and 86 degrees.

“Start early, keep going and hopefully you cover your whole window for take-all root rot,” she says. “The good news is that a lot of the fungicides that you would be putting out in the summer, whether it’s for fairy ring, mini ring or even as we move into early fall for spring dead spot, those are most likely doubling up for your take-all root rot applications as well.”

And what about courses where controlling large patch on zoysiagrass and seashore paspalum is a priority? Navicon Intrinsic brand fungicide is labeled for use on both turf species.

“We need to manage large patch a lot like how we manage spring dead spot,” Lookabaugh says. “Usually, you can get by with two apps in the fall and then two apps as you’re coming out of winter and greening up. That’s a standard program. If you have a particularly mild winter and your soil temps stay above 55 degrees, you might need to continue large patch applications longer into the fall as well.”