Identifying Yellow Spots in Nevada Lawns: Melting-Out Disease vs. Insects

The Scene

Reno, NV: 8-inch yellow spots, temps in 90s. Sow bugs, earwigs present. Owner considers Scotts Summerguard.

Don’t Guess—Identify the Grass First

Different diseases attack different grasses. What grass? Fescue? Bluegrass? Bermudagrass? The answer changes everything.

Likely Culprit: Melting-Out Disease

• Common fungus in Washoe County.
• Attacks both cool- and warm-season grasses.
• Produces 8-inch spots that coalesce into larger patches.
• UNCE earwig factsheet – earwigs are mostly beneficial predators (mites, soft-bodied insects). Mulch foundation plants to draw them away from seedlings.

Why Not Scotts Summerguard

Applying chemicals to healthy grass creates problems: kills microbes, builds thatch, fosters dependency. Healthy grass resists disease naturally.

Next Steps

1. Identify grass species.
2. Compare symptoms to melting-out photos.
3. If fungal: horticultural cornmeal (10 lbs/1,000 sq. ft.) or baking soda spray.
4. Improve cultural practices: deep watering, proper mowing, organic nutrition.