Dr. Phyto

Creeping bent

Agrostis stolonifera

Diseases & pests on this plant

• dollar spot (lawn disease)Clarireedia jacksonii

  Small, round, straw-coloured sunken spots about the size of a coin (2–6 cm) that can merge into larger bleached patches; individual grass blades show a light tan lesion with a darker reddish-brown band right across the leaf; in early morning dew a fine white cobwebby mycelium can be seen. Most common on fine turf in warm days with cool dewy nights.

• pink snow mouldMicrodochium nivale

  Patches of dead seedlings emerging after snowmelt, pinkish-white fluffy mycelium covering plants in cold humid mornings, surviving plants are stunted with brown crown rot.

• Pythium root rotPythium aphanidermatum

  Yellowing + wilting leaves despite wet soil (the diagnostic combination), brown mushy roots when plant is unpotted, foul earthy smell from rotting roots, plant easily pulled from pot with most root system left behind in mix, stem base softening + black at soil line in severe cases.

• Take-all patchGaeumannomyces avenae

  Roughly circular, sunken patches 5–60 cm across, at first orange-bronze then bleached straw to grey, with the worst symptoms on bentgrass. The centre often recovers and is colonised by weeds or other grasses, giving a 'frog-eye' ring. Roots are blackened, rotted and pull away easily; worst on alkaline, sandy or newly limed soils 1–3 years after establishment.

• Turf anthracnose (basal rot and foliar blight)Colletotrichum cereale

  Irregular yellow to orange-bronze patches, often most severe on annual meadow-grass (Poa annua) under stress. Foliar blight shows reddish-brown blighting of leaves; the more damaging basal rot blackens and rots the crown and stem base so plants pull out easily. With a hand lens you can see tiny black fruiting bodies bearing stiff black hairs (setae) on dead tissue. Worst in summer on low-nitrogen, drought-stressed, compacted or close-mown turf.

• Grey snow mould (Typhula blight)Typhula incarnata

  Circular bleached, straw-grey to silvery patches up to about 30 cm across that appear as snow melts in late winter and early spring. Leaves within the patch are matted and water-soaked, often with a greyish-white fungal felt; the diagnostic clue is tiny hard reddish-brown to dark resting bodies (sclerotia, pinhead-sized) embedded in the dead leaves and crowns. Damage is usually to the foliage only, so affected lawns commonly recover as growth resumes.

• sheath blightRhizoctonia solani
• Pythium damping-off + root rot (multi-host)Pythium ultimum

  Seedlings rot at soil line + collapse (damping-off), brown mushy roots when plants pulled up, plants stunted + yellow despite watering, sudden plant collapse during stress periods, foul earthy smell from rotted tissue.

• Brown ring patch (Waitea patch)Waitea circinata var. circinata

  Yellow to bronze rings and arcs from a few centimetres up to 60 cm across, mainly on annual meadow-grass (Poa annua), that can look like a smaller, yellower version of brown patch. Rings often turn tan and slightly sunken; in cool, wet spring weather a thin web of mycelium may be visible in early morning. Roots and crowns can be discoloured but the disease is usually foliar and recovers with growth, so it is mostly a problem on fine sports turf rather than home lawns.

• Thatch accumulation (lawn)Lawn thatch accumulation

  The lawn feels soft, spongy and bouncy underfoot, and a thick brown layer of dead stems and roots can be seen between the green leaves and the soil when you part the grass. The turf dries out quickly, water runs off or sits on top, and the grass becomes thin, pale and prone to scalping and disease.

• red thread (lawn disease)Laetisaria fuciformis

  Irregular patches of bleached, straw-pink grass from a few cm to ~25 cm across; close up, tiny coral-pink to red gelatinous threads and branching needles bind the dead leaf tips together — the diagnostic sign; in damp weather a faint pink cotton-wool web may show. Grass is killed only at the leaf, not the root, so the lawn recovers.

• Soil compaction (lawn)Lawn soil compaction

  Grass grows thin, weak and pale along paths, gateways, play areas and other heavily walked routes, with hard ground that is difficult to push a fork into. Water puddles on the surface after rain instead of soaking in, and moss and weeds often move into the worn lines.

• Fairy ringMarasmius oreades

  Arcs or complete rings, from under a metre to many metres across, of dark-green, fast-growing grass, often with a band of dead or thinned turf just inside, and small tan mushrooms appearing after rain. In dry weather the ring zone becomes hydrophobic (water-repellent) so the grass there wilts and browns even when surrounding turf is green; a mushroom smell and white fungal threads are found in the thatch and soil.