Dr. Phyto

lawn (perennial ryegrass turf)

Lolium perenne

Diseases & pests on this plant

• 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.

• Japanese beetlePopillia japonicaEU-notifiable quarantine organism

  Adults are bright metallic green with coppery wing-cases and small white tufts of hair along the sides of the abdomen; they feed in groups in sunshine, skeletonising leaves between the veins (a lacy look) and chewing flowers and fruit of a huge range of plants (rose, grape, lime, fruit, soft fruit); the white C-shaped grubs eat grass roots, causing brown patches of lawn that lift like a carpet.

• leatherjackets (crane fly larvae)Tipula paludosa

  Yellowing, thinning and dead patches of lawn that lift easily because the roots have been eaten; greyish-brown, legless, tough-skinned grubs up to ~3 cm ("leatherjackets") are found in the top few cm of soil when you lift a patch; birds, badgers or foxes tear up the turf to feed on them; damage peaks in spring as overwintered larvae feed.

• 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.

• 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.