Septoria leaf spot is a fungal disease of the leaves of many grasses. Gray-green spots develop near the leaf tips, later fading to yellow then grayish-white. The spots may reach an inch or more in length. Small brown to black fruiting bodies of the fungus typically appear in the dead areas. Overall, the infected areas of the lawn appear scorched. Disease development is favored by cool, wet weather, unmowed or long turf, and poor nutrition. The fungus typically survives in diseased plants and plant debris. It is spread by splashing water or contaminated equipment, but can also be carried on the seed.

Management Options

Non-Chemical Management

Plant mixtures of improved bluegrass varieties.
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, especially in the fall, as part of a balanced fertilizer regime.
Provide good aeration and drainage. Remove thatch and aerify as needed.
For more information on proper care of lawns, including fertilizer 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

None recommended

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Caption: Septoria leaf spot (tip blight) Photo by: R.S. Byther

WSU Extension

Hortsense