Treating fungal disease

Common diseases

• Brown patch: circular brown areas, often with a darker smoky edge, in hot, humid weather.
• Dollar spot: small, coin-sized straw-colored spots that merge, often in dry soil with humid nights and low nitrogen.
• Red thread: pinkish-red threads on the leaf tips, common in cool, damp weather on underfed lawns.

Change the conditions first

Fungus needs leaves that stay wet for hours. Most outbreaks fade once that stops:

• Water only in the early morning, never in the evening.
• Water deeply and less often, so the surface dries between waterings.
• Improve airflow: prune overhanging shrubs, and scarify heavy thatch.
• Feed correctly; red thread and dollar spot often mean the lawn is short of nitrogen, while brown patch is worse on overfed lawns.
• Collect clippings from affected areas so you do not spread it.

When to use a fungicide

When the disease is spreading quickly despite those changes, use a lawn fungicide authorized in your country, following its label. Treat promptly and as directed, as fungicides protect healthy grass better than they cure badly damaged grass. Afterwards, reseed any patches that do not recover.