Brown spots in bermuda grass usually trace back to one of a handful of culprits: a fungal disease, insect feeding below the soil line, environmental stress, or a cultural mistake like poor mowing or excessive thatch. Fungal infections account for the majority of cases, with spring dead spot and dollar spot ranking among the most common and destructive. Pinpointing the actual cause matters because the fixes differ wildly, and treating for the wrong problem wastes time and money while the real issue spreads.
Fungal Diseases Are the Most Likely Cause
Bermuda grass is a warm-season turf, and warm-season grasses are prone to a cluster of fungal pathogens that produce distinctive brown or tan patches. The three you are most likely to encounter are large patch, dollar spot, and spring dead spot. Each looks a little different and strikes under different conditions, so telling them apart is the first step toward a fix.
Large patch, caused by the soil fungus Rhizoctonia solani, shows up as circular areas of orange-tan grass that start small and can grow to several meters across if left unchecked. The outer ring of the patch often has a distinctive orange hue where the fungus is actively killing leaf sheaths. Large patch tends to flare in spring and fall when soil is moist and temperatures are moderate, then goes quiet during the heat of summer when bermuda is growing its fastest.1Crop Science. Review of the biology and management of large patch of warm‐season turfgrasses
Dollar spot produces much smaller bleached-out circles, roughly the size of a silver dollar, though individual spots can merge into larger irregular patches. The fungus persists as resting structures in thatch and soil for long periods, waiting for favorable conditions. Lawns that are low on nitrogen are especially vulnerable, because the grass lacks the vigor to outgrow the damage.2Semantic Scholar. Dollar spot on turfgrass
Brown patch (also caused by Rhizoctonia species, but distinct from large patch) produces irregular brown areas during hot, humid nights, particularly when the turf stays wet overnight from irrigation or heavy dew. If you pull on the grass blades in an affected area and they slide out easily at the base, the culprit is almost certainly one of these Rhizoctonia diseases.
Spring Dead Spot Deserves Special Attention
Spring dead spot (SDS) is the single most damaging disease of bermuda grass in the transition zone and cooler parts of the warm-season belt. Unlike most turf diseases, you do not actually see SDS when the fungus is active. The pathogen, most commonly Ophiosphaerella herpotricha, infects roots and stolons during fall when soil temperatures drop, killing them through the winter. The damage only becomes visible in spring, when the rest of the lawn greens up and circular dead patches remain bleached and lifeless.3Plant Disease. Ophiosphaerella herpotricha, a cause of spring dead spot of bermudagrass in Kansas
This timing mismatch confuses a lot of homeowners. The brown circles appear in April or May, but the infection happened the previous October. Treatments applied in spring, after the damage is already visible, accomplish nothing because the fungus has already done its work and gone dormant. Weeds often colonize the dead patches, adding insult to injury.
SDS tends to hit hardest on bermuda that has been established for three or more years, especially in lawns with heavy thatch or compacted soil. Hybrid bermuda cultivars used on golf courses and sports fields are particularly susceptible, partly because they cannot reseed themselves and rely entirely on vegetative spread to fill damaged areas.
How to Time Fungicide Treatments for Maximum Effect
Because fungal diseases cause the majority of brown spots, fungicide applications are the most common chemical fix. But timing matters more than product choice for most of these pathogens, and the timing is often counterintuitive.
For spring dead spot, the best results come from fall applications made before the fungus has finished colonizing roots. Research on SDS fungicide timing has consistently shown that treating when soil temperatures are around 13°C (roughly 55°F) provides the best suppression.4Crop Science. Optimizing fungicide application timing for spring dead spot based on soil temperature and season Studies comparing single and split applications found that two fall treatments, or one in spring plus one in fall, gave the most cost-effective disease control.5PubMed. Influence of Fungicide Application Timings on the Management of Bermudagrass Spring Dead Spot Caused by Ophiosphaerella herpotricha In trials on hybrid bermuda, various application rates all provided equivalent control when averaged across timing windows ranging from August through early November.6Plant Health Progress. Method and Timing of Fungicide Applications for Control of Spring Dead Spot In Hybrid Bermudagrass
The practical takeaway: if SDS has been a recurring problem on your lawn, start a preventive fungicide program in early fall. A soil thermometer is inexpensive and far more useful than a calendar date, since soil temperature varies by region and year. Target that 55°F window, apply a second treatment two to four weeks later, and you are covering the period when the fungus is actively colonizing roots.
For dollar spot, the fix is often cultural rather than chemical. Because nitrogen-deficient turf is more susceptible, a balanced fertilization program that keeps the lawn adequately fed during the growing season can reduce outbreaks without any fungicide at all. If you do need a fungicide for dollar spot or large patch, contact fungicides work for mild cases, while systemic products are better for established infections. Rotate between chemical classes to prevent resistance.
Insects That Feed Underground
Not every brown patch is a fungus. Grubs and billbugs feed on bermuda grass roots and stolons below the soil surface, and the damage they cause looks remarkably similar to a fungal patch at first glance. The key difference is what you find when you tug on the grass or peel back the turf. Grub-damaged turf lifts like a loose carpet because the roots have been chewed away, whereas fungal-damaged turf still has an intact root system.
White grubs, the larval stage of various scarab beetles, are among the most destructive root-feeding pests in lawns. They feed on roots from late summer through fall, and the damage often appears as irregular brown areas that do not respond to watering. Research on hybrid bermuda has shown that treatments promoting stronger root growth, including certain beneficial soil bacteria and adequate nitrogen fertility, can increase the turf’s tolerance to grub feeding.7PubMed Central. Rhizobacterial treatments of tall fescue and bermudagrass increases tolerance to damage from white grubs Neonicotinoid insecticides applied preventively in early summer, before grub populations peak, remain the standard chemical control.
Hunting billbugs (Sphenophorus venatus vestitus) are another pest with a preference for bermuda grass. Adults feed on stems near the surface while larvae bore into stolons and roots. Billbug damage tends to appear in sunny, well-drained areas and is easy to mistake for drought stress. One clue: if you see fine, sawdust-like frass at the base of damaged stems, billbugs are likely responsible.8Florida Entomologist. Sphenophorus venatus vestitus (Coleoptera: Curculionidae) Preference for Bermudagrass Cultivars and Endophytic Perennial Ryegrass Overseed
Dog Urine and Other Chemical Burns
Small, distinct brown circles with a dark green ring around them are the classic sign of dog urine damage. The popular explanation is that the nitrogen in urine “burns” the grass like an overdose of fertilizer, and the green ring forms where the nitrogen is diluted enough to stimulate growth. That story is partly right, but research has found that the main damaging agent is actually lactic acid, not nitrogen. In controlled greenhouse tests on lawn grasses, a simulated urine solution containing urea and ammonium sulfate at realistic concentrations caused only slight tip discoloration, while lactic acid at the concentration found in dog urine killed the grass outright, producing damage that looked identical to real urine patches.9Crop Science. Lactic Acid is a Major Contributor to Dog Urine Injury in Cool‐Season Lawn Species
That study was conducted on cool-season species rather than bermuda, but the mechanism is relevant to any lawn grass exposed to the same chemistry. Bermuda’s ability to spread vegetatively from stolons gives it an advantage in recovering from small urine spots, but the acid-driven damage still happens. Watering the spot within a few hours of the dog urinating dilutes the lactic acid before it kills the crown tissue, which is the single most effective home remedy. Dietary supplements marketed to reduce urine damage in dogs have limited evidence behind them.
Fertilizer burn looks similar and follows the same logic: too much soluble salt or acid in one spot overwhelms the grass. Granular fertilizer that clumps or overlaps during application produces streaks or patches of dead turf surrounded by excessively green grass. Watering in fertilizer immediately after application prevents this.
Thatch Buildup and Mowing Problems
Bermuda grass is a prolific grower, which is great for recovery but creates a thatch management challenge. Thatch is the layer of living and dead stems, roots, and runners that accumulates between the green leaf tissue and the soil surface. A thin layer (under half an inch) is normal and even beneficial, cushioning the turf and insulating roots. But when thatch gets thick, it reduces water infiltration, harbors insects, and creates ideal conditions for fungal diseases.10International Turfgrass Society Research Journal. Evaluating biological thatch control in turfgrass
Thick thatch also causes a sneaky form of browning called scalping. Because the mower rolls on top of the spongy thatch layer, the effective cutting height dips into the grass crowns on any slight bump or rise. The result is patches of brown, shaved-down turf in random spots across the lawn. Core aeration once or twice a year and vertical mowing (dethatching) help keep thatch in check. Bermuda’s aggressive growth means it recovers from dethatching quickly, so you can be more aggressive with it than you would be on a slower-growing grass.
The condition of your mower blade matters more than most people realize. Research comparing dull and sharp mower blades found that dull blades reduced turf quality and increased the incidence of leaf spot disease, because ragged cuts leave torn tissue that is more vulnerable to fungal entry. Dull-mowed turf also had lower shoot density over time, creating a thinner stand that is more prone to weed invasion and visible browning.11Agronomy Journal. Mower Blade Sharpness Effects on Turf Sharpening or replacing your mower blade every 20 to 25 hours of mowing time is a cheap preventive measure that pays off in disease reduction alone.
Soil and Water Issues
Bermuda grass is famously drought-tolerant once established, but it does go dormant and turn brown when water is withheld for extended periods. Dormancy browning is uniform across the lawn, which distinguishes it from the patchy browning of disease or insects. The grass is not dead; it is waiting for water. Regular irrigation brings it back, usually within a couple of weeks.
A less obvious water-related problem is soil water repellency. In sandy soils, organic coatings can build up on sand particles and cause the soil to resist wetting. Water beads on the surface or channels through in narrow paths, leaving dry pockets that the turf’s roots cannot reach.12HortScience. Evaluation of Direct Application of Enzymes to Remediate Soil Water Repellency The resulting brown spots look random and do not follow the usual patterns of disease or insects. Wetting agents (surfactants) applied as a soil drench can break the hydrophobic barrier and restore even moisture distribution. Core aeration also helps by physically disrupting the repellent layer.
Compacted soil creates a different but related problem. Heavy foot traffic, parking, and clay-heavy soils all compress the soil structure, reducing the pore space that roots need for air and water. Bermuda in compacted areas thins out and browns, especially during heat stress. Annual core aeration is the standard fix, and on high-traffic lawns, twice a year is better.
How to Diagnose the Cause Before You Treat
Throwing a fungicide at every brown spot is tempting but wasteful if the problem is grubs, drought, or compaction. A few quick checks can narrow down the cause before you spend any money:
- Tug test: Grab a handful of brown grass and pull. If the turf lifts up with no root resistance, the roots are gone, pointing to grubs or billbugs. If it holds firm, the roots are intact and a fungal disease or environmental stress is more likely.
- Pattern: Circular patches with a distinct border suggest a fungal pathogen. Irregular, wandering patches that follow foot traffic or drainage patterns suggest compaction or poor water distribution. Small distinct circles with a green ring suggest dog urine or fertilizer burn.
- Timing: Browning that appears in spring on a lawn that was fine in fall is classic spring dead spot. Browning that appears in late summer, especially after humid nights, points to brown patch or large patch. Dollar spot peaks in late spring and early fall when nights are cool and dew is heavy.
- Soil check: Dig up a small section at the edge of a brown patch. Look for white C-shaped grubs, sawdust-like frass from billbugs, or darkened and rotted roots from fungal infection. Healthy roots should be white or light tan.
If you are still unsure, your local cooperative extension office can often diagnose a turf sample for free or a small fee. The diagnosis is worth it if you are dealing with a persistent or spreading problem, because misidentifying the cause can mean months of wasted treatment.
Filling In Dead Patches
Once you have treated the underlying cause, bermuda’s aggressive spreading habit works in your favor. Common bermuda (seeded varieties) can fill in moderate patches on its own within a few weeks during peak summer growth, as stolons and rhizomes creep into the bare area from the edges. Keeping the damaged area well-watered and lightly fertilized speeds the process.
Hybrid bermuda is a different story. Because hybrids are crosses between two Cynodon species, they are sterile and cannot be established from seed. Recovery depends entirely on vegetative spread from stolons and rhizomes, or on replanting with sod or sprigs.13Grasses. A New Method for Hybrid Bermuda Grass (Cynodon dactylon × C. transvaalensis Burtt.-Davy) Vegetative Propagation For large dead patches on a hybrid lawn, plugging or sodding the area is often faster than waiting for the surrounding grass to fill in. Cut plugs from a healthy area of the lawn, space them six to twelve inches apart in the bare spot, and keep them moist. In warm weather, full coverage typically takes four to eight weeks.
Spring dead spot patches deserve a special note: because weeds colonize those circles quickly, you may want to apply a pre-emergent herbicide to the dead spot while waiting for bermuda to fill in. Just be aware that some pre-emergent products can slow stolon growth into the bare area, so read labels carefully and choose a product labeled as safe for bermuda establishment.
When Brown Is Just Dormancy
Bermuda grass turns brown every winter across most of its range. This is normal dormancy, not disease, and no treatment is needed. The entire lawn goes uniformly straw-colored after the first hard frost and stays that way until soil temperatures climb back above roughly 65°F in spring. Homeowners new to bermuda sometimes panic at the sight, especially if they moved from a region with cool-season grasses that stay green year-round.
If you cannot stand the winter brown, overseeding with perennial ryegrass in fall provides a green cover through winter. The ryegrass dies off naturally as bermuda breaks dormancy in spring. The trade-off is that the ryegrass competes with bermuda for water and nutrients during the transition period, which can slow bermuda’s spring green-up and potentially thin the stand. Many golf courses accept that trade-off for aesthetics, but for a home lawn, letting bermuda go dormant and saving the water is often the simpler choice.
One legitimate concern with winter dormancy is distinguishing it from winterkill. Bermuda that was stressed going into winter, whether from late-season disease, heavy thatch, or poor fertility, may not come back fully in spring. Patches of permanently dead turf amid otherwise greening bermuda look a lot like spring dead spot, and in some cases the two overlap. If your lawn has a history of SDS, the fall fungicide program described earlier is the best insurance against losing turf over winter.