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Stay on schedule to maintain healthy turfgrass

By for CAES News

With the heat of summer bearing down on us, University of Georgia Cooperative Extension turfgrass specialists recommend that residents stick to a schedule for healthy lawn maintenance.

“Just stay on schedule. We’ve been on a fairly good weather pattern this year, so stay on track taking care of your warm- and cool-season grasses by maintaining mowing heights, fertility programs and irrigation schedules,” said Clint Waltz, an Extension turfgrass specialist with UGA’s College of Agricultural and Environmental Sciences.

If you have warm-season grasses, you’re still in the clear to aerate your lawn this summer. Waltz recommends homeowners core-aerate their lawns — at minimum — every three to four years, but suggests once or twice a year in more heavily compacted areas. “Ultimately, the more oxygen you get to the root system the better,” said Waltz.

When it comes to irrigation, about an inch of water is needed per week, but lawns shouldn’t be watered too often. “Although we’ve had a good bit of rain in some parts of the state this summer, it’s typical to start seeing very hot, dry conditions late in summer and early fall, and we’re already seeing those conditions in some areas. The irrigation mantra is to water lawns deeply and infrequently,” said Waltz. He tells residents to space out their irrigation schedules to about twice a week, making sure to get good saturation at each watering to encourage deeper root growth.

“As far as disease issues go, dollar spot in Bermuda grass and zoysia grass has been number one in home lawns in the last few weeks,” Waltz said. He attributed the spike in cases to weather patterns typical of Georgia summers — late evening showers and high nighttime relative humidity.

Dollar spot disease makes circular discolorations only a few inches in diameter. Spots may run together causing large, irregular patterns. Blades of grass have straw-colored lesions along one edge that spread across the leaf blade until the tips die back. The leading edge of dieback is reddish brown. White mycelium — the vegetative part of a fungus that looks like a mass of branching strings — may be associated with patches when turf is wet.

“Most commonly, when we see dollar spot appearing after prolonged rainfall events, we recommend homeowners look for strobilurin fungicide products  — under the brand names Heritage, Disarm, Compass and Insignia — or DMI (demethylation inhibitor) fungicides — under the brand names Eagle, Banner, etc. There are many to choose from and all of them work well. If the weather stays dry for the next week, don’t apply a fungicide, but if you have continued rain in your area, go ahead and make a fungicide application,” explained Waltz. “However, dollar spot can sometimes be associated with a lack of nitrogen, in which case homeowners can add about .5 to .75 pound of nitrogen per 1000 square feet on warm-season grasses,” said Waltz.

Weed control in turfgrass this late in the season will purely rely on postemergence herbicides. “The most important thing here is proper weed identification and the use of prescriptive herbicides,” cautioned Waltz. “Broad spectrum products are not as good at knocking back weeds because they are not targeting any particular species, and it’s really not economically or environmentally wise to make blanket applications to your lawn.”

If you’re in the northern part of the state, be prepared to embrace the annual “fall swoon” of tall fescue. “It’s hanging in there, but in late July and early August the hot, dry conditions will trigger a defense mechanism in tall fescue,” explained Waltz. “The canopy begins to open up to conserve resources until late September and then will use those stored resources to regenerate. This happens every year, so don’t be alarmed. It will get bad, then worse, and then will start to turn around again in the fall.”

For tall fescue, maintenance varies slightly from warm-season grasses. Waltz recommends deep and infrequent irrigation, no summer fertilizer applications, aeration in September or October, and the use of fungicides as a preventative measure against brown patch.

Georgia’s summer climate is ideal for brown patch fungal disease — areas of dead grass surrounded by a reddish-brown or purplish halo — to thrive. Ranging from a few inches to several feet in diameter, this disease occurs during periods of high humidity and warm temperatures (75-85 degrees Fahrenheit). After two to three weeks, the center area of brown grass may recover and turn green, resulting in a doughnut shape of dead brown grass.

“Try to find a fungicide with a 28-day residual to help maintain the canopy, especially when there is limited air movement through late summer and early fall. Ideally, homeowners should rotate chemical classes to prevent resistance issues,” Waltz said of measures to prevent brown patch disease.

It’s still a good time to plant warm-season grasses statewide, according to Waltz. “It’s a little too late to seed establish if you are anywhere north of the fall line, but sod is still good to go statewide for about another month or so,” he explained.

Lawn calendars are great resources to have on hand year-round so you can make the best, most timely decisions to help maintain a healthy lawn. Each calendar provides species-specific information regarding mowing height, water and fertilization needs, pH range, aeration and weed control.

UGA calendars for the various turfgrass species can be viewed and printed at GeorgiaTurf.com. The following calendars cover some of the most common turfgrass varieties.

Warm-season lawn calendars:

Cool-season lawn calendar:

 

For more resources from UGA's interdisciplinary turf team, visit turf.caes.uga.edu.

Emily Cabrera is the public relations coordinator for the Integrated Pest Management program at the University of Georgia.
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