Red thread patches are irregular circular, ragged patches of light tan to pink and develop under what conditions?

• A. Small white specks
• B. Large circular yellow patches
• C. Irregular circular, ragged patches of light tan to pink; develop during long periods of humid weather
• D. Straight red lines

Answer: (C)

Red thread disease is favored by cool-season grasses under extended leaf wetness and high humidity. It produces irregular circular, ragged patches of light tan to pink, and you can often see fine red or pink threadlike growth on the blades. When humid weather lasts for long periods, those patches expand and merge into larger, irregular areas, which matches the description. The other patterns don’t fit red thread: small white specks aren’t the symptom; large circular yellow patches point to different issues; straight red lines aren’t how this disease presents. To manage, improve drainage and irrigation practices to reduce leaf wetness, ensure adequate nitrogen, and apply fungicides if conditions persist.