How to Identify and Eliminate Lawn Pests

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

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McCain: Microdochium nivale: yearly bluegrass, bluegrasses, fescues, ryegrasses, zoysiagrass: circular spots of 12 inches that can expand to 12 inches; leaves initially appear watersoaked, then reddish brown, and lastly bleached; minute, gelatinous spore masses sometimes 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 lawn residues: minimize shade and enhance soil aeration and water drainage; water suitable length of time; prevent excess nitrogen, especially 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 borders 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, leaving thinned locations throughout the turf; spores are windborne: warm temperature levels (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 deficiency: lower shade; improve soil aeration and water drainage; avoid dry spots and too much nitrogen fertilizer; keep as high a cutting height as possible: fungicides available but typically not required Pythium blight (grease spot), triggered by Pythium sp., on a ryegrass and bluegrass yard.

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Ali Harivandi: Pythium spp.: all lawns: little, circular spots (26 inches) that run together; blackened leaf blades quickly wither, turn reddish brown, lie flat, stick together, and appear greasy; roots might be brown; in damp conditions, masses of fungal mycelium might appear: low spots that stay wet; warm temperature levels (8095F daytime, > 68F night time); makes it through as spores in soil for extended periods: decrease shading; improve soil aeration and water drainage; water appropriate length of time; prevent trimming damp yard and using high levels of nitrogen during hot, humid weather condition: fungicides readily available but mainly avoided by cultural practices in California Patches of tall fescue turfgrass contaminated with Rhizoctonia blight.

Curing Damaged Grass Quickly

Credit: Arthur H. McCain: Rhizoctonia solani AG 2-2LP: bermudagrasses, kikuyugrass, St. Augustine turf, zoysiagrass: first looks like small, irregular brown patches or rings that can increase the size of to many feet in diameter; centers might recover leading to rings of unhealthy turf; 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 usually not contaminated and plants often recuperate; soil-inhabiting fungi that forms fine, fungal threads in soil or on turfgrass: excess thatch and mat in addition to cool temperatures (6070F); damp soil conditions: reduce 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; preserve thatch less than 1/2 inch: fungicide helpful if disease severe in past Red thread damage to turf foliage.

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McCain: Laetisaria fuciformis: bentgrasses, bermudagrasses bluegrasses, fescues, ryegrasses: red thread may eliminate turfgrass in spots that are 28 inches in size, or the illness may take place over large areas without killing the plants; pink web of fungal threads bind the leaves together; look for pink, gelatinous fungal crusts projecting from the leaves to assist determine this disease: common under conditions of moderate air temperature levels (6075F) and extended periods of leaf wetness; often appears on plants deficient in nitrogen throughout durations of cool or warm temperature levels if there is sufficient moisture (e.g., excess watering or rains): appropriate irrigation and fertilization can lower the incidence; appropriate nitrogen usually can avoid this illness from happening; prevent drought stress by irrigating turfgrass based upon evapotranspiration needs of the turfgrass; provide appropriate air blood circulation; lower shading: fungicides rarely called for other than in serious cases Rust damage to bluegrass foliage.