Why Is My Grass Turning White?

If it looks like someone sprinkled flour or baby powder over your grass, chance are good that your lawn has a common disease called powdery mildew.

Fear not: Powdery mildew disease (also known as white grass) will not permanently harm your grass. But it can rob your lawn of that attractive, green luster that every lawn owner strives for.

What Are The Signs of White Grass?

If you look closely, you may first see white powder-like spores appearing on leaf blades. As the disease advances, a large part of your lawn may turn powdery white.

(Don’t confuse powdery mildew with snow mold. Both can appear white on the grass, but the white color from snow mold is more of a webbing on top of the grass and not a white coating on the leaf blades.)

What Causes White Grass?

Powdery mildew appears in areas of your lawn that are mostly shaded. It typically appears around trees, buildings and fences. Poor air circulation can also be a culprit. Powdery mildew can appear first thing in the spring and continue to be a nuisance throughout the summer. It favors cool, cloudy conditions and loves high humidity. How severe the outbreak gets largely depends on weather conditions that favor its growth.

Older lawns are more susceptible to powdery mildew than new lawns. If your lawn consists of common-type Kentucky bluegrasses and fine fescues or bermudagrass that are 20 years old or older, it can be more prone to developing powdery mildew.

How Can I Fix It?

  • Anything you can do to increase the amount of sunlight that reaches your grass will help. Try removing low-hanging branches from trees or remove the trees entirely, if practical.
  • Increasing air circulation in heavily shaded areas will help, too. Thinning out shrubbery, trimming trees or installing fencing that can “breathe” are all steps you can take to keep the air moving!
  • Nitrogen fertilizer promotes powdery mildew activity, so cut back on the amount you apply to your lawn.
  • Don’t water your lawn at night. Watering your lawn during early morning hours is best.
  • When reseeding your lawn, use powdery mildew-resistant grasses like shade-tolerant Kentucky bluegrasses, improved fine fescues, fine-textured perennial ryegrass, turf-type tall fescues and bermudagrass. Check with county or university lawn extension services for more help on choosing disease-resistant grass seed varieties suited for your location.