Leaf Spot

Leaf spot or melting out are scattered to general yellow, tan or reddish-brown discoloration and thinning of turf. Individual leaves with circular to elongate purplish, dark-brown, reddish-brown, to black spots often surrounded by a yellow halo. Centers fade to brown, tan then white. Favored by prolonged cloudy, moist weather, moderate temperatures, lush turf growth and shady conditions. 

Dollar Spot

Dollar Spot is bleached spots 4-6" in diameter that coalesce to form large irregular areas of sunken dead turf. Spots have white mycelial strands in the early morning when the turf is wet. Leaf lesions are more or less round, bleached white to light tan with reddish brown to purplish border, often girdling leaf to form characteristic hour-glass shape. Moderate to warm (60-80°F) temperatures, excess humidity, moisture, and, thatch, nitrogen-deficient turf favor disease incidence.

Red Thread

Red Thread is irregularly shaped patches (2-15" diameter) of tan-colored grass with a reddish-brown cast. Dead leaves interspersed with healthy leaves give turf a ragged, scorched appearance. Patches merge to form irregular areas of blighted turfgrass. Infected leaves shrivel and die rapidly from the tip downward, fading to bleached tan. During wet weather, leaves form conspicuous coral-pink, orange to red masses of branched appendages. Favored by cool (65-75°F) prolonged damp, humid weather and slow-growing nitrogen-deficient turf. 

Necrotic Ring Spot

Necrotic Ring Spot is scattered light green patches, 2-inch to 6-inch diameter, enlarging to form light ¬tan to straw-colored sunken, elongated streaks, crescents, or rings up to three feet or more in diameter. Tufts of healthy grass appear in the patch center, giving a "frog-eye" appearance. Favored by cool to mild temperatures, wet then dry conditions, spring through fall, and by stressed turf due to low mowing, excess thatch, compacted soils, nematode, or insect damage. 

Brown Patch

Brown Patch is roughly circular light-brown patches up to several feet in diameter. New but thinned grass can eventually appear in the patch center, resulting in a "frog-eye" appearance. A dark purple to grayish-black "smoke ring" is sometimes noticeable at the perimeter. Dark purplish green leaf spots turn light brown with straw-colored or ash-brown centers surrounded by dark borders. Promoted by high temperature (75-95°F), high humidity, wet soils, extended periods of moisture, excess thatch, and excess nitrogen fertility. 

Rust

Rust is turf that is reddish-brown, yellow to orange, with a weakened, thin appearance. Leaves with small light-yellow flecks that enlarge and rupture to expose round, oval, or elongated powdery, reddish-brown to bright orange or lemon yellow spore-filled pustules. Powdery spores rub off easily on shoes, clothing, and animals. Conditions favoring disease include moderate to warm temperatures (70-85°F), heavy dew, light rains, slow leaf surface drying, low fertility, low soil moisture, and soil compaction. 

Fairy Ring

Rust is turf that is reddish-brown, yellow to orange, with a weakened, thin appearance. Leaves with small light-yellow flecks that enlarge and rupture to expose round, oval, or elongated powdery, reddish-brown to bright orange or lemon yellow spore-filled pustules. Powdery spores rub off easily on shoes, clothing, and animals. Conditions favoring disease include moderate to warm temperatures (70-85°F), heavy dew, light rains, slow leaf surface drying, low fertility, low soil moisture, and soil compaction.