If a well-watered lawn develops brown patches, more likely than not, it has developed a fungal problem. Here are some pointers that might help identify a lawn fungus:
--Dead grass that pulls away from the roots easily;
--Grass blades that are green on their lower portion with the upper part pinched together and brown;
--Yellow-green blotches on blades that eventually bleach to a white or straw color.
Controls for fungus include good cultural methods. Lawn watering is best done early in the day so that grass blades may become dry before nightfall. Watering at night causes grass blades to remain wet for long periods of time, which is a good way to promote fungus. If the lawn has a thick layer of thatch, it should be core aerated in either the spring or fall, or at both times if thatch is heavy. Chemical control would include the use of a fungicide labeled for turf, applied following label directions. To be sure it is a fungal problem, you should submit a turf sample to your local county Extension office. The sample should be about six inches in diameter and include the marginal area between the living and dead grass, and a couple inches of roots. For more information, see fact sheets:
Lawn Care
Necrotic Ring Spot in Turfgrass
Dollar Spot Disease of Turfgrass.

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