New build garden 9 months on

Grass Disease & White Blades


"Dead or white patches of grass seriously impact a yard's appearance and warrant concern.

Numerous diseases and abiotic disorders potentially impact grass, but only a few of these cause grass blades to turn light-colored or white. Knowing the grass species helps to determine which diseases could impact it; and good overall care, including proper irrigation and fertilizer application, limits disease impact.

Fusarium Blight
Fusarium blight, caused by Fusarium fungi, impacts Kentucky bluegrass turf. Foliage killed by Fusarium appears bleached, but first develops as gray-green circles on the grass that can reach several inches in diameter. The basal portion of dead foliage is hard with a reddish rot. Fusarium tends to impact grass most when temperatures are 85 to 95 degrees Fahrenheit, the turf is drought-stressed and growing in full sun, and heavy thatch accumulation exists. Vertical mowing or de-thatching and proper irrigation and fertilizer applications limit the presence of this disease.

Microdochium Patch
Microdochium patch, also referred to as pink snow mold or Fusarium patch, is caused by Microdochium nivale and infects Kentucky bluegrass, annual bluegrass and creeping bentgrass. Infections on turf appear circular and range from 1 or 2 to 12 inches across. Individual blades look water-soaked before darkening to a reddish-brown and finally becoming bleached. Gelatinous spore masses may appear, and fungal threads are present in the early morning. Microdochium patch, which survives in thatch or grass residue, prefers cool, moist conditions and alkaline soils. Limiting shade, proper irrigation, good drainage, avoiding excessive nitrogen fertilizer application, maintaining a slightly acidic soil and supplemental potassium suppress this disease.

Powdery Mildew
Powdery mildew, caused by Erysiphe graminis, primarily impacts Kentucky bluegrass. Infected turf appears grayish-white and individual leaves have a powdery dusting. The fungus tends to attack shade-intolerant cultivars where they receive inadequate sun. Re-seeding shady sites with shade-tolerant cultivars, pruning overhanging branches and surrounding vegetation to increase light penetration and air circulation, and preventative fungicide applications stymie powdery mildew occurrences.

Gray Leaf Spot
Gray leaf spot, caused by Pyricularia grisea, causes bleached spots with dark margins on grass blades. St. Augustinegrass, fescues, ryegrasses and kikuyograss are impacted by gray leaf spot, which prefers warm temperatures, high humidity, and over-watered and over-fertilized lawns. Proper irrigation and fertilization reduce the presence of gray leaf spot and generally eliminate the need for fungicide. Reducing shade by thinning out overhanging tree and shrub branches and increasing air circulation also limits gray leaf spot.

Possible Abiotic Causes
Fertilizer burn can appear as white stripes in turf that develop shortly after fertilizer application in the same pattern that fertilizer was applied. Proper fertilizer application, including uniform spreading, avoiding application when foliage is wet and watering fertilizer in well, reduces the likelihood of fertilizer burns. An iron deficiency appears as bleached or yellow spots on grass blades. This type of deficiency is common in alkaline soils and is corrected by adjusting the fertilizer regimen or altering soil pH."