Brown spots in Bermuda grass lawns are a frequent concern for homeowners, detracting from the turf’s uniform green appearance. These discolored areas can signal various underlying issues, including environmental stressors, pest activity, or disease. Understanding the specific cause of these brown patches is the first step toward effective treatment and restoring lawn health.
Identifying the Causes of Brown Spots
Brown spots in Bermuda grass can result from various factors, each presenting with distinct symptoms that help in proper diagnosis. Understanding these indicators is essential for effective intervention.
Environmental Factors
Drought stress, often from underwatering, causes grass blades to curl and the lawn to appear dull bluish-gray or brown. Footprints remaining visible indicates insufficient moisture.
Conversely, overwatering can also cause brown spots by suffocating roots, leading to yellowing grass, soggy soil, and mold. Bermuda grass can suffer from heat stress during prolonged high temperatures, causing wilting and discoloration from blade tips downwards.
Additionally, compacted soil restricts oxygen flow to roots, hindering nutrient absorption and leading to weak turf that may brown.
Pest Infestations
White grubs, beetle larvae, feed on grass roots, causing irregular brown patches that are easily pulled up.
Chinch bugs cause irregular patches of yellowing or wilted grass, especially in sunny areas. Their presence can be confirmed by floating them to the surface.
Armyworms, destructive caterpillars, feed on grass blades, leaving chewed or notched appearances, sometimes with a “windowpane” effect. They can decimate large areas quickly.
Fungal Diseases
Brown Patch appears as sunken, circular patches of dead, tan grass, from a few inches to several feet wide, sometimes with a “smoke ring” of darker, wilted grass at the edges.
Dollar Spot creates small, silver-dollar-sized tan spots (2 to 6 inches wide) that may merge. It often shows bleached, hourglass-shaped lesions on individual grass blades with brownish-purple borders.
Leaf Spot initially manifests as small, brown or black spots on leaves, expanding into lesions with tan centers and dark borders. It can progress to “melting out,” rotting sheaths, crowns, rhizomes, or stolons, leading to wilting and browning.
Spring Dead Spot causes circular patches (6 inches to several feet wide) of bleached, dead grass that fail to green up in spring. It often recurs in the same locations, expanding annually, with affected roots, rhizomes, and stolons appearing dark and rotted.
Cultural Practices
Improper lawn care practices can also lead to brown spots. Fertilizer burn results in irregular brown patches where too much fertilizer was applied, dehydrating the grass. Chemical spills, such as from herbicides or gasoline, create distinct, sharply defined dead spots or patterns. Scalping, removing too much grass blade in a single mowing, especially by lowering the height drastically, leads to uneven browning and turf stress.
Solutions for Brown Spots
Addressing brown spots effectively requires tailoring solutions to the identified cause, promoting recovery, and preventing recurrence.
Watering
If underwatering is the problem, deep and infrequent watering encourages deeper root growth, making the lawn more resilient. For overwatered areas, reduce irrigation frequency and allow the soil to dry out between waterings to restore root health and prevent fungal development. Improving drainage, potentially through aeration, can also alleviate excess moisture.
Pests
For grubs, apply appropriate insecticides in late summer or early fall to disrupt their life cycle. Chinch bugs and armyworms may require specific insecticide applications, often best performed in early morning or late evening when pests are most active. Maintaining proper mowing height can also deter some insect infestations.
Fungal Diseases
Fungicides can provide direct control, but improving cultural conditions is crucial for long-term management. This includes proper watering to reduce leaf wetness, avoiding excessive nitrogen fertilization, and managing thatch buildup, as these factors contribute to disease. Aeration can also improve air circulation and reduce soil compaction. For severely damaged areas, reseeding or sodding small patches can help the lawn recover.
Preventing Brown Spots
Proactive measures are crucial for maintaining a healthy Bermuda grass lawn and minimizing the occurrence of brown spots.
Watering
Establish an optimal watering schedule by providing about one inch of water per week, applied deeply in one session rather than frequent, shallow sprinklings. This promotes deep root development, making the grass more resilient.
Mowing
Maintain the correct mowing height; common Bermuda grass thrives when mowed to 1 to 2 inches, while hybrid varieties prefer 3/8 to 1.5 inches. Mow frequently, ideally every 4-5 days during peak growing season, never removing more than one-third of the blade length at a time. This reduces stress and promotes denser growth.
Fertilization and Soil Health
Fertilization should be guided by soil test results, with applications generally occurring 2-4 times per year between March and November. Focus on nitrogen in spring and summer for vigorous growth, and potassium in the fall for winter hardiness. Improve soil health through annual aeration to alleviate compaction and enhance nutrient and water absorption. Consistently monitor for early signs of pests or diseases for timely intervention.
When to Seek Professional Help
While many brown spot issues can be addressed by homeowners, certain situations warrant professional assistance. If damage is widespread, covers a large percentage of the lawn, or spreads rapidly despite your efforts, it may indicate a severe underlying problem requiring expert diagnosis. If recommended solutions fail for a persistent problem, a professional lawn care service or local extension office can offer specialized knowledge and tools. They can conduct detailed soil analyses, identify obscure pests or diseases, and provide targeted treatments, ensuring the long-term health of your Bermuda grass.