Advanced Pest and Fungus Control Strategies

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 temperatures of 8595F; high humidity or rainfall; overwatered and overfertilized turf: irrigate correctly; do not overfertilize; lower shading; boost air motion: fungicides are offered, but cultural controls are more practical Fusarium patch damage to bentgrass grass.

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McCain: Microdochium nivale: annual bluegrass, bluegrasses, fescues, ryegrasses, zoysiagrass: circular spots 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 in some cases seen on dead leaves; white or pinkish fungal threads may be seen in morning; more prevalent in Central and Northern California: regularly cool temperature levels (4065F) and damp conditions; high nitrogen applications in fall; neutral or alkaline soil pH; pathogen makes it through in grass residues: minimize shade and enhance soil aeration and water drain; water proper length of time; prevent excess nitrogen, especially in fall; preserve soil pH in 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 might pass away in hot, windy weather condition, leaving thinned areas throughout the turf; spores are windborne: warm temperature levels (7090F) for bluegrasses, ryegrasses, and fescues; cool temperatures (6070F) for bermudagrass and zoysiagrass; high humidity; low clipped turfgrass; most severe with excess nitrogen fertilization or deficiency: decrease shade; enhance soil aeration and water drain; avoid dry spots and excessive nitrogen fertilizer; preserve as high a cutting height as possible: fungicides offered however frequently not required Pythium blight (grease spot), brought on by Pythium sp., on a ryegrass and bluegrass yard.

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Ali Harivandi: Pythium spp.: all yards: small, circular areas (26 inches) that run together; blackened leaf blades rapidly wither, turn reddish brown, lie flat, stick together, and appear greasy; roots might be brown; in humid conditions, masses of fungal mycelium might appear: low spots that remain damp; warm temperature levels (8095F daytime, > 68F night time); endures as spores in soil for long periods: reduce shading; enhance soil aeration and water drainage; water appropriate length of time; prevent mowing damp lawn and applying high levels of nitrogen throughout hot, damp weather condition: fungicides available but primarily prevented by cultural practices in California Patches of high fescue turfgrass contaminated with Rhizoctonia blight.

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Credit: Arthur H. McCain: Rhizoctonia solani AG 2-2LP: bermudagrasses, kikuyugrass, St. Augustine yard, zoysiagrass: first appears as small, irregular brown patches or rings that can enlarge to many feet in size; centers might recover resulting in rings of infected lawn; leaves and sheaths become watersoaked, wilt, turn light brown, and pass away; plants pull out easily from soil with rotten stolons, in light invasions, roots generally not contaminated and plants typically recuperate; soil-inhabiting fungi that forms fine, fungal threads in soil or on turfgrass: excess thatch and mat together with cool temperatures (6070F); wet soil conditions: reduce shading and enhance soil aeration and water drainage; water proper length of time to a depth of 46 inches; prevent excess nitrogen in the fall; keep thatch less than 1/2 inch: fungicide helpful if disease serious in past Red thread damage to turf foliage.

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McCain: Laetisaria fuciformis: bentgrasses, bermudagrasses bluegrasses, fescues, ryegrasses: red thread might kill turfgrass in spots that are 28 inches in size, or the illness might happen over big areas without killing the plants; pink web of fungal threads bind the leaves together; try to find pink, gelatinous fungal crusts forecasting from the leaves to assist determine this illness: typical under conditions of mild air temperatures (6075F) and extended durations of leaf dampness; typically appears on plants deficient in nitrogen during periods of cool or warm temperatures if there is sufficient moisture (e.g., excess irrigation or rains): proper watering and fertilization can reduce the occurrence; sufficient nitrogen typically can prevent this disease from occurring; avoid drought tension by watering turfgrass based upon evapotranspiration requirements of the turfgrass; supply sufficient air circulation; lower shading: fungicides seldom necessitated other than in severe cases Rust damage to bluegrass foliage.