New Turf Diseases to Watch for in 2026

Credit: Lane Tredway: Pyriculria grisea: fescues, kikuyugrass, ryegrasses, St. Augustinegrass: irregular blighted spots of turf with bleached spots with dark margins on leaves; ryegrass develops a fishhook look: daytime temperature levels of 8595F; high humidity or rains; overwatered and overfertilized turf: water properly; do not overfertilize; decrease shading; boost air motion: fungicides are readily available, but cultural controls are more practical Fusarium spot damage to bentgrass turf.

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McCain: Microdochium nivale: yearly bluegrass, bluegrasses, fescues, ryegrasses, zoysiagrass: circular patches of 12 inches that can expand to 12 inches; leaves first 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 prevalent 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 lawn residues: reduce shade and improve soil aeration and water drain; water proper length of time; prevent excess nitrogen, particularly in fall; keep 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 verge on leaf blades, sheaths, and stems; crowns and roots often have a dark brown rot; crown-infected plants may pass away in hot, windy weather condition, leaving thinned areas 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 serious with excess nitrogen fertilization or shortage: minimize shade; enhance soil aeration and water drainage; avoid dry areas and excessive nitrogen fertilizer; maintain as high a cutting height as possible: fungicides readily available however often not warranted Pythium blight (grease area), triggered by Pythium sp., on a ryegrass and bluegrass yard.

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Ali Harivandi: Pythium spp.: all turfs: little, circular spots (26 inches) that run together; blackened leaf blades quickly wither, turn reddish brown, lie flat, stick, and appear greasy; roots may be brown; in humid conditions, masses of fungal mycelium may appear: low areas that remain damp; warm temperatures (8095F daytime, > 68F night time); endures as spores in soil for long durations: decrease shading; improve soil aeration and water drain; water appropriate length of time; avoid trimming wet grass and using high levels of nitrogen during hot, damp weather: fungicides offered but mostly prevented 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 lots of feet in diameter; centers may recuperate resulting in rings of infected grass; leaves and sheaths end up being watersoaked, wilt, turn light brown, and pass away; plants pull out easily from soil with rotten stolons, in light infestations, roots typically not contaminated and plants often recover; soil-inhabiting fungi that forms fine, fungal threads in soil or on turfgrass: excess thatch and mat along with cool temperature levels (6070F); wet soil conditions: decrease shading and enhance soil aeration and water drainage; water suitable length of time to a depth of 46 inches; prevent excess nitrogen in the fall; keep thatch less than 1/2 inch: fungicide useful if illness extreme in past Red thread damage to grass foliage.

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McCain: Laetisaria fuciformis: bentgrasses, bermudagrasses bluegrasses, fescues, ryegrasses: red thread may kill turfgrass in spots that are 28 inches in diameter, or the disease might occur over large areas without eliminating the plants; pink web of fungal threads bind the leaves together; try to find pink, gelatinous fungal crusts projecting from the leaves to assist identify this disease: common under conditions of mild air temperatures (6075F) and extended periods of leaf moisture; typically appears on plants deficient in nitrogen throughout durations of cool or warm temperatures if there is sufficient moisture (e.g., excess watering or rainfall): proper irrigation and fertilization can decrease the incidence; appropriate nitrogen generally can avoid this disease from occurring; prevent drought tension by watering turfgrass based on evapotranspiration requirements of the turfgrass; provide appropriate air circulation; decrease shading: fungicides seldom necessitated except in extreme cases Rust damage to bluegrass foliage.