Brown Patches, Bare Spots, and Weeds: Diagnosing Central Indiana Lawn Problems

Brown patches in a lawn all look similar at first glance. But the cause behind them matters — because watering a fungus problem makes it worse, and treating grubs as a drought problem lets them keep eating.

Here’s how to identify what’s actually wrong with your Central Indiana lawn.

Brown patch fungus (Rhizoctonia solani)

What it looks like: Circular or irregular brown patches, typically 6 inches to several feet across. In early morning you may see a grayish “smoke ring” of dying grass around the edge. Leaves develop tan lesions with dark borders.

When it shows up: Hot, humid weather — usually late June through August in Indiana. Needs overnight temps above 65°F and high humidity.

What makes it worse: Watering in the evening (wet grass overnight = fungal paradise), over-fertilizing with nitrogen in summer, poor air circulation.

The fix:

• Water early morning only (4–8 AM), never evening
• Don’t fertilize with nitrogen during active outbreaks
• Improve air flow — thin out dense shrubs near the lawn edge
• For severe cases, a fungicide labeled for brown patch
• Tall fescue is the most susceptible of common Indiana grasses

Grub damage

What it looks like: Brown patches that feel spongy underfoot. The dead grass pulls up like a loose carpet with no root resistance — because the grubs have eaten the roots. You’ll see small white C-shaped larvae in the top 1–2 inches of soil.

When it shows up: Late summer into fall (August–October) is when damage becomes visible, though the grubs have been feeding for weeks.

The test: Pull up a section of brown grass. If it lifts like a rug and you see C-shaped white grubs in the soil, it’s grubs. More than 5–10 grubs per square foot warrants treatment.

The fix:

• Curative treatment (trichlorfon) if damage is active
• Preventive treatment (imidacloprid or similar) applied in June for the next year
• Skunks and raccoons tearing up the lawn = secondary sign of grubs

Drought / dormancy

What it looks like: Large areas turn tan or straw-colored. Grass feels dry and crunchy but pulls up with resistance — roots are still intact. Usually appears on south-facing slopes and sandy spots first.

When it shows up: Peak summer heat, usually mid-July through August, especially after a dry stretch.

The key difference from disease: Dormant grass is not dead. Once temps moderate and rain returns, it greens back up within 2–3 weeks.

The fix:

• If you want green: 1 inch of water per week, deep and infrequent (one long soaking beats three quick sprinkles)
• If you’re okay letting it go dormant: don’t mow stressed grass, don’t fertilize, don’t aerate. Just wait it out.
• Don’t start watering a dormant lawn halfway through the drought and then stop — that kills it faster than leaving it dormant

Pet urine spots

What it looks like: Small round brown spots (6–12 inches), often with a dark green ring of lush grass around the edge. The ring is the giveaway — nitrogen from the urine over-fertilizes the surrounding grass even as it burns the center.

The fix:

• Flush the spot with water within a few hours if you catch the dog peeing there
• Reseed small dead spots in fall
• No amount of “pet-safe” supplements fully prevents it — dilution is the only real fix

Fertilizer burn

What it looks like: Brown or yellow stripes matching the pattern of the spreader. Sharp edges, geometric shapes.

Cause: Over-application, or fertilizer applied to wet grass on a hot day.

The fix: Water heavily to dilute, then wait. The lawn will recover in 3–6 weeks as new growth comes in.

Salt damage (winter)

What it looks like: Brown or bare strips along driveways, sidewalks, and streets in early spring. Grass fails to green up where rock salt accumulated over winter.

The fix:

• Flush the affected area with water in early spring to leach salt
• Reseed the dead strip
• Switch to calcium chloride or sand for next winter — easier on grass than rock salt

Compacted soil

What it looks like: Thin grass or bare spots in high-traffic areas — paths to the garage, under swing sets, along fences. Grass is stunted even with water and fertilizer.

The test: Try to push a screwdriver straight down into the soil. If it takes effort or won’t go past 2 inches, soil is compacted.

The fix: Core aeration. This is exactly the problem aeration was designed for — it breaks up compaction and gets air, water, and roots moving again.

Chinch bugs

What it looks like: Irregular brown patches that start small and spread outward, typically in sunny, dry areas. Grass yellows, then turns straw-colored. Unlike grubs, the roots are intact.

The test: Push a coffee can (both ends removed) into the soil at the edge of a brown patch. Fill with water. If chinch bugs are present, they’ll float to the top within 5–10 minutes.

The fix: Insecticide labeled for chinch bugs. Rare in well-maintained, properly-watered lawns.

Weeds in brown spots

Once grass dies from any of the above, weeds move in — because bare soil doesn’t stay bare. Crabgrass, clover, nutsedge, and plantain are the usual Indiana culprits.

The real fix for weeds isn’t spraying — it’s fixing the underlying lawn. A thick, healthy, properly-mowed lawn crowds weeds out on its own. Spraying weeds without addressing why the grass is thin is a never-ending cycle.

Decision flowchart

1. Does the dead grass pull up like a rug? → Grubs
2. Is it a circular patch with a “smoke ring” edge in hot humid weather? → Brown patch fungus
3. Is it summer and everything is uniformly tan/crispy? → Drought/dormancy
4. Small round spots, dark green ring? → Pet urine
5. Straight stripes matching the spreader pattern? → Fertilizer burn
6. Along the driveway/sidewalk in early spring? → Salt damage
7. High-traffic area, soil is hard? → Compaction (aerate)
8. None of the above and it’s spreading? → Chinch bugs or disease — get a pro look

The bottom line

Don’t treat the symptom without knowing the cause. Watering a fungal outbreak feeds it. Spraying insecticide on drought damage does nothing. Seeding into compacted soil wastes seed.

Most Central Indiana lawn problems are diagnosable in under 60 seconds with a sharp eye and maybe a screwdriver.

---

Not sure what’s killing your grass? Tom can take a look and tell you straight — and whether it’s something to fix or just wait out. Covering New Palestine, Fortville, Greenfield, and Hancock County. Call (317) 517-0728.