Bermuda grass is a warm-season grass requiring a soil temperature of 65-Fahrenheit at least to grow in green.
It’s expected to turn brown when temperatures drop in the fall. When your Bermuda grass goes brown during the growing season, that’s a problem.
It can be caused by numerous issues, including heat stress in the peak of summer. When it’s more problematic is when you get a brown patch of Bermuda grass that seems to be getting bigger.
When that’s the case, you need to identify the cause, fix the problem and get some repair work done before it spreads to healthy parts of your lawn.
Why is my Bermuda grass turning brown?
Brown Bermuda grass (during the growing season when it’s not dormant) can be caused by soil compaction, cold spells, or growing in the shade, which slows down photosynthesis. Fungal infections that can cause Bermuda grass to brown include leaf spot, spring dead spot and brown patch disease.
1. Soil compaction
When your soil is too compact, the roots will suffocate. A lack of oxygen and poor drainage rots the roots, killing Bermuda grass.
To prevent soil compaction, Bermuda grass lawns need aerated.
It is possible for brown patches or rings of brown to appear on your lawn when it lacks water. Thatch stops water penetrating deep into the soil. Prevent thatch build up by dethatching your lawn once per year in early spring.
As soil compaction causes the grass to dry up faster, creating brown patches, you can revive it faster by hand sprigging Bermuda grass, which is essentially growing new grass blades through propagation.
2. Temperatures below 55-Fahrenheit
Being a warm-season grass, Bermuda grass goes dormant in the winter. When it’s in dormancy, the grass goes brown naturally. Usually at the end of fall then greens up in early spring.
Soil temperatures below 55-Fahrenheit is when the grass goes dormant. It greens up in spring, thriving when soil temperatures are continuously hovering around 65-fahrenheit and warmer.
If there’s an early cold snap either in spring or fall, Bermuda grass can go into dormancy earlier than expected.
3. Lacking sunlight
When growing in shade, such as under the canopy of bushy plants, it’s a good idea to mow at a higher height to help the grass capture more light and retain heat.
The downside to long grass blades is that the sunlight gets blocked on the lower portions of the grass sprigs.
Bermuda grass sprigs lacking sunlight exposure will be brittle. You can find longer blades growing in dappled sunlight are elongated with the lower portion of the leaves turning brown.
There are times when Bermuda grass just won’t grow. One of those is when you’re trying to grow grass under pine trees or similar plants that put out a huge canopy, shading the grass.
Bermuda grass needs six hours of full sun daily to all parts of the grass. Blades longer than 2-inches crowds out the lower part of the grass, causing it to brown from the bottom up.
Mowing it to expose the browning parts to sunlight helps it recover.
Regular mowing keeps the grass from browning
During peak growing season, good lawn care for Bermuda grass is frequent mowing at precise heights.
Ideally, the grass should be kept between an inch to 2-inches.
When sunlight is scarce, keep it around 2-inches. When sunlight is plentiful, mowing twice weekly to keep the height controlled at a height under 2-inches prevents the grass getting too long that the lower portion of the grass sprigs turn brown.
Diseases that cause Bermuda grass to turn brown
Symptoms of disease is when the browning spreads, or you get brown spots that get bigger. Irrigation problems cause browning only on the area that’s struggling to get water. When it’s spreading, it’s more likely a fungal infection.
4. Brown patch disease
Brown patch is a fungal disease. Not a description of a symptom, like the name suggests. It’s caused by the fungal pathogen Rhizoctonia.
It’s particularly problematic on warm-season grasses including Bermuda grass, Zoysia, and St. Augustine. More so in early spring and late fall when temperatures take a sudden spike upwards of 70-Fahrenheit at night.
Bermuda grows best when the nighttime temperature is above 60-Fahrenheit. Combined with high daytime temperatures, it keeps the soil temperature at 65-Fahrenheit and higher.
When night temperatures climb to between 70-Fahrenheit and 90-Fahrenheit, that’s when the Rhizoctonia fungus can get out of control.
If the spread is severe, bringing it under control may require a fungicide treatment, preferably with a liquid fungicide rather than granular.
Fungicides to treat brown patch disease on Bermuda grass include:
Spot treating with fungicides should be done once per fortnight, but treatments aren’t cheap. It’s approx. $20 per 1,000 sq ft.
Given the nature of fungicides requiring precise applications and dosages, it’d be worth considering hiring a licensed landscaper with experience treating brown patch disease.
5. Dollar Spot
Dollar spot causes brown spots on Bermuda grass. It’s a soil-borne fungus infection that’s easier to prevent than it is to get rid of.
Despite being a soil fungus, it doesn’t disturb the roots. Only the grass blades brown.
Dry soil is what causes it to brown Bermuda grass. The problem that lets dollar spot set in is that the roots are dry but the morning dew and moist air on the grass essentially rots it from the top down.
Preventing dollar spot is done by using a fertilizer that’s high in nitrogen. That should be done monthly anyway. It’s one of the reasons each of the best fertilizers for Bermuda grass have high nitrogen levels.
Additionally, steps need to be taken annually to ensure water reaches the roots. Do that by dethatching in early spring, and core-aerating the lawn – piercing holes in it.
6. Leaf spot
Leaf spot on Bermuda grass start as tiny brown spots on the leaves, but if it’s not treated, symptoms worsen causing the grass to wilt, yellow, and eventually turn brown when it’s dying.
The fungus Helminthosporium is the cause and it’s most problematic during a wet spring when the temperatures are just below 65-Fahrenheit. At that temperature and time of year, the grass is just coming out of dormancy.
Thatch is a contributing factor to its development, which is why it’s beneficial to dethatch in early spring. Similar to dollar spot, leaf spot is easier to prevent than it is to treat.
7. Spring dead spot
Spring dead spot is a fungal disease that only appears in highly maintained lawns. The more care you take with fertilizing, the more appealing it is to this fungal disease.
Identifying it is easy. It causes brown circles on Bermuda grass. Depending on the severity, it can look like a bleaching effect.
Where you see brown spots, pick a sprig of grass to inspect it. Spring dead spot rots every part of Bermuda grass. The rhizomes (underground roots), crowns, stems and stolons (the above ground runners).
Effectively, what’s brown on top will be black rot below the surface. It’s only prevalent in the spring, and in nitrogen-rich soil.
When this occurs, the grass can’t outcompete weeds so you’re more likely to see weeds sprouting up within the brown patches of dead or dying Bermuda grass.
Treating spring dead spot in Bermuda grass is a balancing act between fertilizer application rates throughout the growing season, and applying a fungicide in late fall when the grass goes dormant.
Recovery is slow because you’re essentially stopping the spread of fungal spores, while encouraging new grass growth to replace the damaged patch of brown Bermuda grass.
Frequently Asked Questions related to why Bermuda grass turns brown
Is it normal for Bermuda grass to be green on top but brown underneath?
When Bermuda grass is above two inches, the top of the grass sprig crowds out the stem underneath. That’s why when you brush your hand across Bermuda grass, you’ll see the stems are brown. It needs kept mowed to 2-inches maximum for sunlight to reach all parts of the grass.
Does Bermuda grass need top dressed?
Top dressing with either compost or an organic soil mix helps prevent heat stress causing brown patches on your lawn. It’s common in the peak of summer when the soil struggles to retain moisture. To treat dry brown patches caused by heat stress, rake in a half inch of organic compost or soil.
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