Keywords

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Northern lawns and turf of golf greens often show round light patches as the snow melts in early spring. Such a disease is called snow mold and may be due to one of several fungi, sometimes to two appearing together.

Microdochium (Fusarium)

Rots.

Fusarium nivale, Teleomorph, Monographella nivales

(see ▶Microdochium nivale). Pink Snowmold, Fusarium Patch, most important on bentgrass on golf courses but infecting other turf grasses and winter wheat and winter rye.

Microdochium nivale

(formerly Fusarium nivale, Teleomorph, Monographella nivales). Pink Snowmold, Fusarium Patch, most important on bentgrass on golf courses but infecting other turf grasses and winter wheat and winter rye. Irregularly circular patches, from 1 to 2 inches to a foot or more, appear as snow is melting. They are whitish gray, often with a pinkish tinge, and several patches may run together to cover large areas. Individual plants have a bleached appearance, feel slimy when wet. Spores are formed in salmon-pink sporodochia over stomata in leaves. They are sickle-shaped, one-to three-septate. Perithecia are produced on the luxuriant white mycelial mat.

Abundant moisture in the fall, snow falling on unfrozen ground, deep snow, and a prolonged, cold wet spring are predisposing factors, but the presence of snow is not a requisite for the disease. Severity is increased by applying fertilizer in late autumn and an excess of organic matter in the soil. Reports differ as to susceptibility, but Colonial, Washington and Metropolitan bentgrasses appear to be more resistant then Seaside bent.

Sclerotium

Blights.

Sclerotium rhizodes

Frost Scorch, String of Pearls, in northern states. Not exactly a snowmold but appearing in early spring with bleached, withered leaves covered with rows of tiny sclerotia. Collect clippings when mowing diseased areas to remove sclerotia on leaf tips.

Typhula

Basidiomycetes, Aphyllophorales

Fruit body erect, simple, like a little club, on a long stipe from a sclerotium; basidia with four sterigmata and simple, hyaline spores.

Typhula incarnata

Snowmold of turf and lawn grasses, Typhula Blight, common in eastern United States. As the snow disappears in spring, a felty white mycelial mat is seen over grass and adjacent soil. Plants wither and turn light brown or tan in roughly circular patches, very conspicuous against the green of the rest of the lawn. The chief diagnostic character is the presence of very small, tawny to hazel brown spherical sclerotia in large numbers over affected parts. These can be made to fruit in the laboratory into rose-colored sporophores up to 1 inch tall.

Control

The disease gradually disappears as moisture decreases and temperature and sunlight increase; so control seldom seems necessary. Six weeks after striking cases of snowmold, lawns are often uniformly green and show little sign of having been affected. Phosphate fertilizers are said to decrease injury from Typhula.

Typhula idahoensis

Snowmold on wheat and grasses in Idaho and Montana. Sclerotia are chestnut brown, sporophores fawn to wood brown, less than 1/2 inch high.