Brown patches. Yellow rings. Thinning turf that doesn't respond to water or fertilizer. Lawn diseases can look a lot like drought stress, insect damage, or just a lawn that needs more attention. The problem is that treating the wrong thing — or treating a disease the wrong way — can make things worse instead of better.

Here's a guide to identifying the most common lawn diseases in Texas and what to do about them.

Why Lawn Disease Identification Matters

Lawn diseases are caused by fungal pathogens that are already present in most soils. They don't cause problems under normal conditions — they become a problem when environmental conditions favor their growth. That means temperature, humidity, moisture, mowing practices, fertilization, and soil health all play a role in whether a disease takes hold.

Diagnosing correctly before treating is important because fungicide applications are not a cure-all, they're not cheap, and applying the wrong product or applying it at the wrong time won't help. Diagnose first. Treat second.

Brown Patch (Rhizoctonia solani)

What it looks like

Brown patch is one of the most common lawn diseases in Texas. It appears as roughly circular brown or tan patches, often with a darker brown or "smoke ring" border around the edge. Patches can range from a few inches to several feet across and may merge together in severe cases. The grass blades in affected areas typically show brown lesions and may pull away from the sheath easily.

When it appears

Brown patch is most active when nighttime temperatures are between 70°F and 80°F and humidity is high — typically fall and spring in Central Texas. It can also appear in summer during periods of high humidity.

Grass types affected

St. Augustine, tall fescue, and other cool-season grasses are most susceptible. Bermuda grass can be affected but is generally more resistant.

Contributing factors

• Excessive nitrogen fertilization, especially in fall
• Watering in the evening (leaves grass wet overnight)
• Thatch buildup
• Poor air circulation
• Overwatering

Take-All Root Rot (Gaeumannomyces graminis)

What it looks like

Take-all root rot causes yellowing, thinning, and eventual death of grass in irregular patches. Unlike brown patch, the damage is happening underground — the fungus attacks the root system, causing roots to turn black and rot. Affected grass pulls up easily because it has no healthy roots holding it in place.

When it appears

Take-all root rot tends to appear in spring and fall in Texas, often following periods of wet weather. It can be confused with other problems because the above-ground symptoms (yellowing, thinning) look similar to nutrient deficiency or drought stress.

Grass types affected

St. Augustine is the primary target in Texas. Bermuda grass can also be affected.

Contributing factors

• Wet, poorly drained soils
• Soil pH imbalances
• Overwatering
• Excessive thatch

Dollar Spot (Clarireedia jacksonii)

What it looks like

Dollar spot gets its name from the small, silver-dollar-sized brown spots it creates in the lawn. Individual spots may merge into larger irregular patches. Grass blades in affected areas show tan or straw-colored lesions with reddish-brown borders. In the morning, you may see white, cobweb-like mycelium on the grass when dew is present.

When it appears

Dollar spot is most active during warm days and cool nights with high humidity — spring and fall in Texas.

Grass types affected

Bermuda grass and zoysia are commonly affected. St. Augustine can also develop dollar spot.

Contributing factors

• Low nitrogen levels
• Drought stress
• Watering in the evening
• Thatch buildup

Gray Leaf Spot (Pyricularia grisea)

What it looks like

Gray leaf spot causes small, olive-green to brown lesions on grass blades that develop a gray center with a dark brown border. In severe cases, the lawn can look scorched or blighted. It spreads rapidly under the right conditions.

When it appears

Gray leaf spot is a summer disease — it thrives in hot, humid conditions with temperatures above 80°F. It's most common during Texas summers following periods of rain or heavy irrigation.

Grass types affected

St. Augustine is highly susceptible to gray leaf spot. It's one of the most damaging summer diseases for St. Augustine lawns in Texas.

Contributing factors

• Excessive nitrogen fertilization in summer
• Overwatering
• High humidity
• Warm temperatures

Pythium Blight (Pythium spp.)

What it looks like

Pythium blight moves fast. It can kill large areas of grass within 24 to 48 hours under the right conditions. Affected areas appear water-soaked and greasy at first, then quickly collapse and turn brown. White, cottony mycelium may be visible in the early morning.

When it appears

Pythium blight requires very specific conditions — high temperatures (above 85°F), high humidity, and wet soils. It's most common during hot, humid Texas summers.

Contributing factors

• Overwatering or poor drainage
• Compacted soils
• Excessive nitrogen
• Poor air circulation

Is It Disease or Something Else?

Lawn diseases are frequently misdiagnosed because their symptoms overlap with other common problems:

• Drought stress causes browning but usually affects the whole lawn evenly rather than in distinct patches
• Insect damage (chinch bugs, grubs) can look similar to disease — check for actual insects before treating for disease
• Nutrient deficiency causes yellowing that may look like disease
• Scalping or mowing damage creates brown areas that can be mistaken for disease
• Chemical burn from fertilizer or herbicide misapplication creates distinct patterns

When in doubt, look at the pattern, check the roots, look for insects, and consider recent weather and lawn care history before reaching for a fungicide.

Professional Lawn Disease Diagnosis in New Braunfels

If you have brown patches, yellowing turf, or thinning grass that isn't responding to normal care, Committed Lawn Care can help diagnose what's going on and recommend the right treatment. We serve homeowners throughout New Braunfels and surrounding Central Texas communities.

Call or text Committed Lawn Care at 512-222-9122.