Powdery mildew is a common lawn disease which creates a dusty white coating on grass blades. Large infected areas look as if the grass has been dusted with flour or lime. Heavily infected leaves turn yellow and die.

The powdery mildew fungus grows best in high humidity, low light and cool temperatures. Consequently, powdery mildew generally occurs in the spring and fall, and is most severe in shaded areas, where air circulation is poor.

• The best strategy for controlling powdery mildew involves the use of shade tolerant and resistant grass varieties.
• Techniques such as selective pruning and proper fertilization can also help.
• Beware of too much fertilizer. Excess nitrogen allows lush growth, which is easily attacked.
• Chemical control is not generally necessary for home lawns.

When landscaping a new area, use grass groundcovers more adapted to shade than turf grass. Space trees to avoid producing areas of dense shade and poor air circulation. Similarly, many areas in established lawns can be opened up to light and air with pruning and thinning.

For more information, contact your local county Extension office.

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