By Cat Holmes
University of Georgia
"Turf grass diseases are hard to diagnose but relatively simple to treat," said Alfredo Martinez, a plant pathologist with the University of Georgia College of Agricultural and Environmental Sciences.
"Now that grass is greening up, people should go take a walk and look carefully over their lawns," Martinez said. "Plant diseases are just like human diseases. Prevention is essential, and the earlier you treat them, the better."
Diagnosing turf problemsWhen scouting the lawn, what should you be looking for?
"Turf grass diseases usually show up as discolored spots, bare patches and thin grass," Martinez said. "At this time of the year, there are two main turf diseases in Georgia: brown patch and dollar spot."
The symptoms of brown patch are circles or patches of thin, yellowing grass, Martinez said. The circles may range from several inches to several feet across.
"The causal agent of brown patch, a fungus called rhizoctonia, grows outwards," Martinez said. "The resulting patch looks like a 'doughnut' of brown or yellow discolored grass with green in the middle. The green appears because as the fungus spreads outwards, weeds or new grass starts to grow in the middle, creating a doughnut effect."
Small white patches, only a few inches in diameter, are probably dollar spot, Martinez said. Sometimes the spots are close together and may appear to look like larger patches. But if on close inspection, it's an aggregate of small, whitish, circular patches, it's dollar spot.
Treating turf problemsThe best resource for diagnosing and treating turf disease is a county extension agent, Martinez said.
"A county agent can play a major role in helping prevent, diagnose and treat turf grass problems," Martinez said. "It's hard for someone who isn't trained to diagnose turf grass diseases. The county agent may recommend fertilization treatment, adding more light or air movement or fungicides. And if they're uncertain about the problem, they will contact us."
Preventing turf problemsAn ounce of prevention is worth a pound of cure when it comes to turf, Martinez said. One of the easiest ways to prevent turf disease, he said, is to avoid overwatering.
"Improper watering habits account for a large number of the cases of turf grass disease," Martinez said. "People tend to water for short intervals several times a week. Plant diseases love high humidity on foliage, and too-frequent watering actually encourages diseases."
It's much better to water long enough for the moisture to soak 2 to 3 inches into the soil, he said.
Martinez says watering regimes should be based on the type of soil. For example, one good watering each week may be enough for sandy soils, while clay-based soils hold more moisture, and water intervals can be extended.
It's also important to water grass before noon, Martinez said, so the turf has time to dry out thoroughly before nightfall.
Proper fertilization procedures and rates are also essential to avoid turf diseases. "Each grass species has particular fertility requirements," he said.
Another key is to plant grass that's appropriate for the region and your yard. Again, Martinez recommends consulting with a county extension agent.
"Different grasses do much better in different areas," he said. "A county agent can assess an area and recommend turf suited to that particular location and use."
If you're planting grass this spring, Martinez said, prepare the soil properly. It's important to remove all rocks, stumps and debris. Take soil samples to your country extension agent to get a good idea of what, if any, amendments your soil might need.
Proper grading is another key. Low areas are bad news for turf, because that's where water collects, and excessive water promotes disease.
(Cat Holmes was a science writer with the University of Georgia College of Agricultural and Environmental Sciences.)