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What Is the White Stuff Growing on Top of Planted Grass?

Grass that has white stuff growing on the surface may have been infected with a fungal disease called powdery mildew. Powdery mildew is the most widespread fungal disease that infects plants, according to Colorado State University's website. Gardeners must treat powdery mildew symptoms with cultural management options, because the disease cannot be treated with fungicide.
  1. Powdery Mildew

    • Powdery mildew overwinters on dead and diseased grass, according to the University of Rhode Island's website. Once humidity rises in the spring, powdery mildew fungal spores begin to germinate. Spores may infect grass in less than two hours. In fact, powdery mildew doesn't need wet foliage for germination or spreading. Gardeners may see powdery mildew symptoms spread over their turf. Identifying powder mildew symptoms quickly allows gardeners to respond before their grass becomes badly damaged.

    Symptoms

    • Gardeners may see a talcum-like white growth on the top of their grass. Powdery mildew fungal spores harms grass by using the nutrients in the grass blades. Nutrients used for grass blade development get used up by the fungal spores. Powdery mildew's symptoms are worse during dry weather and grass grown in the shade. Shade-intolerant grass types experience severe powdery mildew symptoms. Plant shade-tolerant grass to reduce the risk of fungal diseases in shady areas.

    Cultural Control

    • Numerous methods reduce powdery mildew symptoms on grass. For example, allow your grass to grow slightly higher than its recommended growing height, as suggested by the University of Rhode Island website. Grass that is generally maintained at 2 1/2 inches may be grown to 3 inches. Once the blades are cut, energy is redirected from the roots to develop new blades. Also, avoid using excessive nitrogen on your lawn. Excessive nitrogen stresses grass' root systems, because they are forced to produce quick growth.

    Shade-Tolerant Grass Types

    • Plant shade-tolerant grass types such as fescues, creeping bentgrasses, zoysia and St. Augustine. Refrain from planting Bermuda, Bahia, seashore paspalum, Kentucky bluegrass because they don't tolerate shade. Allow your shade-tolerant grass types to grow slightly higher than grass grown in full sunlight. Grass grown in the shade needs more surface area for photosynthesis. You can also prune off branches or remove trees to increase the sunlight in your yard.