If doughnut-shaped rings of dead grass are popping up in your lawn, it may be because the recent onslaught of rain created ideal conditions for brown patch disease
Brown patch on turfgrass is caused by a fungal disease known as Rhizoctonia solani. Circular patches of dead grass that range from a few inches to several feet in diameter occur during periods of high humidity and warm temperatures (75ºF to 85ºF).
It loves humid summers
Georgia's summer climate is ideal for this fungus. Brown areas of dead grass are surrounded by a reddish-brown or purplish halo. After two to three weeks, the center area of the brown grass may recover and turn green, resulting in a doughnut shape of dead brown grass.
This common lawn disease is prevalent during warm, humid summer months. It attacks all turfgrasses including bermudagrass, tall fescue, centipedegrass and zoysiagrass. This time of year it affects tall fescue the most. Some varieties of these grasses are resistant or less susceptible to the disease, but none are totally immune.
Conditions that favor brown patch include excessive nitrogen fertilizers, frequent watering, watering late in the day (or too much rain) and high humidity.
Follow these tips
To help prevent brown patch, don't apply excessive amounts of nitrogen fertilizers. Use only enough fertilizer to maintain a reasonably healthy, green turfgrass based on a soil test. Excessive nitrogen tends to favor the development of brown patch due to lush, tender growth of grass that is more susceptible to attack by the fungus.
Water early in the morning to allow grass foliage to dry before nightfall. Most fungi grow and develop during the night when given adequate moisture. It’s best to water lawns early in the morning, less often and more deeply. Turfgrass needs approximately 1 inch of water per week, ideally given in one or two applications. With all the rain this year, no one should need to water their lawn. If you’re watering your lawn this summer, you’re probably watering too much.
Mow the lawn slightly higher than normal during periods of excessively high heat conditions. This reduces stress to turfgrasses and helps reduce the possibility of disease. Common turfgrasses and their recommended mowing heights are as follows: bermudagrass - 1 to 1.5 inches; centipedegrass - 1 to 2 inches; St. Augustinegrass - 2 to 3 inches; zoysiagrass - 1 to 2 inches; and tall fescue - 2 to 3 inches. Tall fescue, especially, performs better when kept at a taller height in the summertime.
Avoid or remove excess thatch from the lawn. Thatch is decomposing grass stems, shoots and roots — not clippings — that have accumulated at the soil surface. More than half an inch of thatch will retain excess moisture and favor disease development. Thatch buildup can be caused by improper mowing practices and over-fertilization.
Mow your lawn often enough that no more than one-third of the grass height is removed in a single mowing. This may require mowing as often as once or twice a week, which can be a challenge with all the rain we’ve been getting. Keep your mower blades sharp and don’t mow grass when wet.
Dethatching machines (vertical mowers and core aerators) can be rented for use on lawns that have accumulated too much thatch. This should only be done in early summer for warm-season turfgrasses and in the fall for tall fescue. Bagging grass clippings is usually not necessary if you are mowing your grass frequently enough and following recommended fertilization practices for your turfgrass. (For more information on grasscycling, see the University of Georgia Cooperative Extension publication website at www.caes.uga.edu/publications/.
Bring in a sample
If you think you have brown patch or any other diseases in your lawn, bring a sample of the turfgrass (about a 4x4 inch square, including the roots) to your local UGA Extension office for proper diagnosis. An ideal sample for diagnosis is half dead and half alive, taken from the outer edge of a dead patch. A fungicide recommendation may be required if the problem cannot be corrected with cultural practices.
Paul Pugliese is the Agriculture and Natural Resources agent for the University of Georgia Extension office in Bartow County.
FAQs
Prolonged wetness from dew, rain, nighttime or evening watering, or poor drainage—or any other activity that keeps grass blades wet during weather in which temperatures are above 80 degrees F during the day and 65 degrees F at night—create ideal conditions for developing this serious fungal disease.
Can too much water cause brown spots on lawn? ›
Many customers equate a brown spot in their lawn as the lawn needing more water, when actually the opposite is what is often required. Too much water saturates the soil, filling up all the air space between the soil particles with water.
Does overwatering a lawn cause fungus? ›
Too much water can cause fungus growth, one of the most noticeable being mushrooms. Also, red/orange coloring on your grass may indicate a type of rust fungus. Seeing colorful splotches on the grass blades can also mean you've got fungus growth. Watering just enough can help keep your grass green and fungus-free.
Why is my lawn getting brown patches? ›
Over time, lawns can develop excess thatch buildup that acts like a barrier at the soil line. A similar thing happens when lawn aeration for compacted soil is overdue. Water, nutrients and oxygen can't move normally. Fungal lawn diseases — marked by brown spots — come next.
How does brown patch fungus spread? ›
The brown patch pathogen pro- duces no spores. Therefore, the disease spreads by radial expansion of mycelium over leaf blades and by mechanical maintenance practices. The fungus survives in thatch and turf debris between active periods.
Does overwatering cause brown spot? ›
Underwatering, overwatering and lack of humidity can cause dry brown spots, especially along the edges of leaves or on leaf tips. Solution: Stick a finger in the soil. If it feels bone dry, you're probably underwatering. If it feels soggy, you're likely overwatering.
What does too much water on lawn look like? ›
A big sign of overwatering grass is color – or rather lack of color. Your lawn should be a deep green color. But if it looks yellow, brown, or even pale in nature, it could be getting too much water.
How do I tell if my lawn is overwatered? ›
Signs of Overwatered Grass
Spongy soil. If you step on your lawn and it feels spongy or squishy then there is likely too much water. A spongy feeling can also indicate a layer of thatch that is too thick.
Can lawn fungus be spread by mowing? ›
Only mow your lawn when it's dry. Spores are more easily spread when grass is wet. Don't run the mower over dead or diseased areas – it will carry disease into healthy parts of the lawn.
How do I get rid of lawn fungus permanently? ›
Treatments:
- Correct your watering regime.
- Water in the early morning instead of the evening.
- Remove grass clippings after you mow (otherwise, you'll spread the disease).
- Remove excessive thatch buildup.
- Aerate your lawn every year.
- Mow the lawn regularly.
- Apply a fungicide in the affected area.
Compendium® fungicide is an excellent choice for preventive control of brown patch. It contains the active ingredients azoxystrobin and propiconazole and delivers broad-spectrum control of brown patch, as well as all major turf diseases.
How long does it take for a brown patch to heal on a lawn? ›
In many cases, the turf recovers on its own after a couple of weeks, especially after a change in the weather, like starting in early September when the nighttime temperatures start to cool off.
Will brown patches of grass grow back? ›
Brown patch disease attacks and kills blades of grass, but the root system remains intact. This means the affected area can usually recover. However, in some cases, new turf or reseeding the patch may be necessary.
Can too much water cause brown spots in grass? ›
Watering your lawn too often increases your lawn's risk of developing brown patch, which occurs when the surface is wet but the soil is dry. Aim for a routine of once every 3-4 days, and water deeply–approximately 1/2 inch per session.
How do you treat brown patch fungus naturally? ›
One of the most effective methods is to use baking soda.
Baking soda helps to create an alkaline environment, which will help to kill the fungus. You can either spread baking soda on your lawn manually, or you can mix it with water and spray it on your lawn. Other natural killers include: Dish soap.
What is the difference between brown patch and chinch bug? ›
Chinch bugs usually won't kill the roots, so once they are under control, the lawn should recover. Brown patch disease is a little harder to diagnose, but the patches are usually rounder than chinch bug damage. The blades of grass will have brown spots and streaks on them, often merging to turn the entire leaf brown.
Can an overwatered lawn recover? ›
Then, you should address any problems that you've created such as fungal growth, a pest problem, or thatch build-up. Most of the time, lawns will bounce back from overwatering unless it's been going on for such a long time that the grass is dead.
How do you revive brown grass spots? ›
How can I revive brown grass? For brown or yellowing grass, proper irrigation and soil enrichment are key. Rake dead spots, plant new grass seed, water regularly, and use high-phosphorus fertilizer to encourage healthy growth.
