Published on 07/17/03

Recent rains create turf turmoil in Georgia

By Sharon Omahen
University of Georgia

The abundance of rain in Georgia is, for the most part, a blessing. Your turf grass may not agree.

"We've had one of the wettest Mays and Junes on record," said Clint Waltz, a turf specialist with the University of Georgia College of Agricultural and Environmental Sciences.

Compacted soil

"Too much water combined with traffic can cause the soil to become compacted. And when it does dry out, there isn't enough room for oxygen to get to the plant's roots," Waltz said. "Two of turf grasses' major needs are water and air. Too much of one can affect the other."

So how to do know if your soil is compacted?

"You'll see wear patterns on the turf once it dries out," he said. "Or there will be thin areas and spots that are extremely hard and too tough to penetrate."

To solve the problem, Waltz suggests renting an aerator or hiring a service. An aerator is a device that punches holes in the soil. These holes are typically 3 to 6 inches deep and will allow for much-needed air flow.

Run the aerator over the affected area two to three times in different directions, he said.

"Not all areas of the lawn need aerification," said Waltz. "Only treat the area that needs it. And make sure you do this while the grass is actively growing."

Some aerators actually pull out cores of turf and soil. Either dispose of these or work them back into your lawn, he said.

If your soil is clay, he recommends leaving the new air holes unfilled and letting them fill in naturally. If your soil is sandy, he said, you can incorporate an organic matter as an amendment to improve its nutrient- and water-holding capacity.

Waltz said centipede and St. Augustine grasses don't respond to aerification as well as Bermuda and zoysia.

Disease pressure

Besides compacting soils, the recent rains have increased turf disease pressure.

"By far the biggest turf disease problem caused by the rain has been brown patch," said Mila Pearce, a UGA integrated pest management specialist. Pearce works closely with UGA Extension Service county agents to identify submitted disease samples and make recommendations for homeowners.

"Brown patch is caused by a fungus that primarily gets in the root and crown," she said. "It causes large brown patches that will slowly expand if they aren't treated."

Pearce said homeowners often make brown patch worse by acting on their first reaction. "Their instinct is to throw nitrogen to it to green it up," she said. "This is the absolute worst thing to do and it makes it 10 times worse."

If you have to fertilize, Pearce said, select a low-nitrogen type. Brown patch is typically seen on zoysia and Bermuda grasses.

Homeowners with St. Augustine grass are reporting a different disease problem.

"We're seeing a lot of gray leaf spot in St. Augustine grass, which is a direct result of all this wet weather," Pearce said. "It leaves gray, water-soaked lesions and eventually causes drying and dieback."

One dose won't do it

To control these diseases, you have to develop a schedule.

"Homeowners think they can spray one time and be done," Pearce said. "One spraying will only reduce disease. It's not uncommon to have to keep a spraying schedule of every 10 to 14 days."

Pearce said aerating the soil and reducing thick thatch areas will help prevent diseases. To control them, she recommends selecting a chemical treatment such as Immunox, Terraclor or Cleary's 3336.

"One thing you can't control is Mother Nature. So as long as it rains, you'll just have to be prepared to make continual sprays," Pearce said. "Spraying is not going to remove it. It's just going to reduce it and keep it from spreading."

Sharon Omahen is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.