Lawn & Grass Diseases

Brown Patch

Affected Grasses: Bentgrass, annual bluegrass, and bermudagrass are damaged more than coarser bluegrass, fine-leaved fescue, and ryegrass. Creeping bentgrass is particularly susceptible when cut at golf-green height and grown under a high level of maintenance.

Symptoms: Brown patch appears in two forms. On close cut bentgrass, the patches are 2 to 3 feet wide, roughly circular, and light brown. When moist, a dark purplish to grayish black ring (“smoke ring”) of wilted and blighted grass blades may mark the advancing margin.On high-cut lawn grass, the roughly circular, irregular patches are light brown, matted down, and up to about 2 feet wide. The patches sometimes develop green centers and may resemble the “frogeyes” of summer patch and necrotic ringspot.

Dollar spot

Affected Grasses: Dollar spot is a serious disease of creeping bentgrass, Kentucky bluegrass, fine-leaved fescue, ryegrass, zoysia, and bermudagrass.

Symptoms: On closely cut bentgrass and bermudagrass putting greens, the disease appears as sunken, round, tan to straw-colored spots roughly the size of a silver dollar. On Kentucky bluegrass, fine-leaf fescue, higher cut bentgrass, ryegrass, zoysia, and bermudagrass, the spots may reach 3 to 8 inches in diameter. If uncontrolled, the spots may become so numerous that they merge to produce large, irregular, sunken areas of straw-colored turf.

Fairy ring

Affected Grasses: Fairy ring may occur in any area where turfgrass is grown

Symptoms: Fairy rings usually appear during spring and early summer as circles or arcs of dark-green, fast-growing grass. A ring of thin or dead grass may develop outside this circle. Fairy rings vary from a few inches to more than 50 feet in diameter, but most are 2 to 15 feet in diameter. After rain, mushrooms or puffballs (the fruiting bodies of the fairy ring fungi) may suddenly appear on the perimeter of the fairy ring.

Gray Snow Mold

Affected Grasses: All cool-season turfgrasses are susceptible, with bentgrasses, annual bluegrass and ryegrasses being most susceptible. Kentucky bluegrass varieties differ in resistance.

Symptoms: During and after snow-melt, gray snow mold appears in roughly circular yellow to whitish-gray patches, from 1 to 3 feet or more in diameter. Wet grass may be matted together and covered with fluffy white to gray mold speckled with numerous amber to dark brown sclerotia.

Gray leaf spot

Affected Grasses: Gray leaf spot can be a very destructive disease of perennial ryegrass in golf course fairways and sports fields, particularly on young seedlings emerging from autumn overseeding. The disease may also occur on tall fescue.

Symptoms: The first symptoms are small, water-soaked leaf lesions which quickly become oblong and gray to light brown in color, often with a purple to dark brown border. Old spots may have a yellow halo and, as the disease progresses, the leaves become completely blighted. Dying leaves often develop a characteristic twist at the leaf tip that resembles a fishhook and helps to differentiate this disease from brown patch or Pythium blight.

Pink Snow Mold

Affected Grasses: Annual bluegrass, bentgrass, Kentucky bluegrass, and ryegrasses are most commonly affected by pink snow mold. However, nearly all cool-season turfgrasses as well as bermudagrasses and zoysiagrasses are susceptible.

Symptoms: The disease first appears as round, water-soaked spots, 1 to 3 inches in diameter, that soon turn into yellow, orange-brown, or reddish brown patches. Patches may enlarge and become light gray or light tan rings up to about 1 to 2 feet across with orange-brown or reddish-brown borders. The patches are usually rounder and smaller than those of gray snow mold.

Pythium Blight

Affected Grasses: All cultivated turfgrasses are susceptible to the various species of Pythium.

Symptoms: Due to its appearance, the disease is also called grease spot, spot blight, and cottony blight. Symptoms include round to irregular, dark, water-soaked. “greasy” or slimy, sunken patches of matted grass, up to 6 to 12 inches wide, which develop in hot or cool, very wet, calm weather. Elongated streaks may develop following water drainage or mowing when the grass is wet.

Summer Patch

Affected Grasses: Kentucky bluegrass turfs that are managed as amenity or sports turf. Other grasses susceptible to these diseases include annual bluegrass and fine-leaf fescues.

Symptoms: First symptoms are scattered. light-green patches, typically 2 to 6 inches in diameter. In warm to hot weather, they soon enlarge and rapidly fade to a dull reddish brown, then a light tan, and finally to a light straw color. The patches may become elongated streaks, crescents, or roughly circular, and are 1 to 3 feet in diameter. Within the areas of dead or stunted grass there are often centers of green, apparently healthy grass resulting in characteristic “frog-eye” or “doughnut” patterns.

Powdery mildew

Affected Grasses: Powdery mildew occurs most commonly on Kentucky bluegrass and, to a lesser extent, on bermudagrass, fine-leaved fescues,and zoysiagrass.

Symptoms: Superficial, white, powdery patches of mildew develop on grass leaves. Heavily infected turf appears dull white, as if dusted with flour. When damage is severe, powdery mildew may kill plants, especially in new plantings in the shade.


Contact the professionals at Rite-A-Way Lawn Care for the best and safest cures to keep from compounding the problem.