Brown blight is a fungal disease affecting the leaves of perennial ryegrass and some fine fescues. Infection commonly occurs during cool, wet periods. The disease is typically worse during the first fall after planting and on grass with insufficient nitrogen. Affected leaves develop small, oval, chocolate brown spots or larger brown streaks up to 3/8" long. The leaves may be girdled and turn yellow, dying back from the tip. Overall, the affected areas of grass look brown and thin and may appear drought-stressed. The disease is spread by infected grass clippings, contaminated equipment, wind, or splashing rain. The fungus can survive in infected plant debris and infected plants. This disease rarely does enough damage to kill grass.

Management Options

Non-Chemical Management

Provide good culture by fertilizing, mowing, and irrigating properly. Vigorous, healthy grass is more disease-resistant.
Water in the morning so grass can dry quickly.
Provide adequate nitrogen, particularly in the fall, as part of a balanced fertilizer regime. Avoid overfertilization.
Provide good aeration and drainage. Remove thatch and aerify as needed.
Plant seed mixtures containing disease-resistant hard fescues (if appropriate for your area).
For more information on lawns, including fertilizer and seeding recommendations, see EB0482E, Home Lawns.

Select non-chemical management options as your first choice!

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides

Chemical applications are not recommended for home lawns because this disease rarely kills grass.

Images

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Caption: Brown blight Photo by: R.S. Byther

WSU Extension

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