Diagnosing Recurring Yellow Patches in Your Lawn

Yellow dying patches that appear in the same spots each summer, resist insecticides, and recover in cooler weather suggest a persistent underlying issue—not insects.

Likely Culprits

• Fungal disease: Look for mushrooms or white mycelial growth under the turf. Summer temperatures often create ideal conditions for fungal activity.
• Buried debris or contaminants: Old wood, construction debris, or contaminated soil can drain nitrogen or harbor pathogens. Probing with a rod may reveal hard obstacles.

Next Steps

Collect whole grass plants (roots and all) from affected and healthy areas for tissue analysis through your local agricultural extension service. A soil test can also reveal nutrient imbalances or contaminants. Fungicides may help if a fungal pathogen is confirmed on grass blades, but proper diagnosis is essential before treatment.