Is Your Lawn Dying? Identify Diseases Now

Credit: Lane Tredway: Pyriculria grisea: fescues, kikuyugrass, ryegrasses, St. Augustinegrass: irregular blighted patches of grass with bleached areas with dark margins on leaves; ryegrass establishes a fishhook look: daytime temperature levels of 8595F; high humidity or rainfall; overwatered and overfertilized grass: water properly; don't overfertilize; reduce shading; increase air motion: fungicides are offered, but cultural controls are more useful Fusarium patch damage to bentgrass turf.

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McCain: Microdochium nivale: yearly bluegrass, bluegrasses, fescues, ryegrasses, zoysiagrass: circular patches of 12 inches that can increase the size of to 12 inches; leaves initially appear watersoaked, then reddish brown, and finally bleached; minute, gelatinous spore masses often seen on dead leaves; white or pinkish fungal threads may be seen in morning; more widespread in Central and Northern California: consistently cool temperature levels (4065F) and damp conditions; high nitrogen applications in fall; neutral or alkaline soil pH; pathogen makes it through in yard residues: decrease shade and improve soil aeration and water drain; water suitable length of time; prevent excess nitrogen, specifically in fall; maintain soil pH between 6.56.7.

Credit: M. Ali Harivandi: Bipolaris spp. and Helminthosporium spp.: bermudagrass, bluegrasses, fescues, kikuyugrass, ryegrasses, zoysiagrasses: circular to extended brownish areas with brown centers and dark brown or purple borders on leaf blades, sheaths, and stems; crowns and roots frequently have a dark brown rot; crown-infected plants might die in hot, windy weather, leaving thinned locations throughout the turf; spores are windborne: warm temperatures (7090F) for bluegrasses, ryegrasses, and fescues; cool temperature levels (6070F) for bermudagrass and zoysiagrass; high humidity; low clipped turfgrass; most extreme with excess nitrogen fertilization or shortage: decrease shade; improve soil aeration and water drainage; prevent dry areas and too much nitrogen fertilizer; preserve as high a cutting height as possible: fungicides available but typically not required Pythium blight (grease area), triggered by Pythium sp., on a ryegrass and bluegrass yard.

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Ali Harivandi: Pythium spp.: all grasses: small, circular areas (26 inches) that run together; blackened leaf blades quickly wither, turn reddish brown, lie flat, stick, and appear greasy; roots might be brown; in humid conditions, masses of fungal mycelium might appear: low spots that stay wet; warm temperature levels (8095F daytime, > 68F night time); survives as spores in soil for long durations: minimize shading; enhance soil aeration and water drain; water proper length of time; prevent mowing damp turf and applying high levels of nitrogen during hot, humid weather: fungicides readily available however primarily avoided by cultural practices in California Patches of high fescue turfgrass infected with Rhizoctonia blight.

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Credit: Arthur H. McCain: Rhizoctonia solani AG 2-2LP: bermudagrasses, kikuyugrass, St. Augustine lawn, zoysiagrass: first appears as small, irregular brown patches or rings that can expand to numerous feet in diameter; centers may recuperate leading to rings of diseased turf; leaves and sheaths end up being watersoaked, wilt, turn light brown, and pass away; plants take out quickly from soil with rotten stolons, in light infestations, roots normally not infected and plants frequently recover; soil-inhabiting fungus that forms fine, fungal threads in soil or on turfgrass: excess thatch and mat together with cool temperature levels (6070F); damp soil conditions: minimize shading and enhance soil aeration and water drain; water proper length of time to a depth of 46 inches; avoid excess nitrogen in the fall; keep thatch less than 1/2 inch: fungicide helpful if illness extreme in previous Red thread damage to grass foliage.

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McCain: Laetisaria fuciformis: bentgrasses, bermudagrasses bluegrasses, fescues, ryegrasses: red thread may kill turfgrass in patches that are 28 inches in diameter, or the illness may take place over big locations without eliminating the plants; pink web of fungal threads bind the leaves together; look for pink, gelatinous fungal crusts predicting from the leaves to help identify this illness: typical under conditions of mild air temperatures (6075F) and extended durations of leaf moisture; typically appears on plants lacking in nitrogen during periods of cool or warm temperatures if there is appropriate wetness (e.g., excess watering or rainfall): correct watering and fertilization can minimize the incidence; appropriate nitrogen generally can prevent this disease from taking place; avoid dry spell stress by irrigating turfgrass based upon evapotranspiration requirements of the turfgrass; provide appropriate air circulation; minimize shading: fungicides hardly ever required other than in severe cases Rust damage to bluegrass foliage.