Turfmate field notes · Diseases

Grey leaf spot

Pyricularia / Magnaporthe disease complex

Leaf lesions and rapid decline in susceptible turf need prompt attention.

Photograph a fresh affected leafTurfmate illustration · not a diagnostic photograph
Original Turfmate educational illustration. Symptoms are a prompt to investigate, not a confirmed diagnosis.

What to look for

  • Oval or elongated tan lesions with darker margins.
  • Spots can appear grey and fuzzy under moist conditions.
  • Leaves may wither; susceptible ryegrass can decline rapidly.

Confirm it before you treat it

Photograph leaves at the advancing edge and confirm the grass species. Matted or greasy ryegrass can resemble Pythium blight. Microscopic or laboratory examination may be needed; the drawing is a visual inspection aid, not a diagnostic photo.

What to do next

  1. Record how quickly the damage is advancing and contact Turfmate promptly if it is spreading.
  2. Review irrigation timing, air movement and prolonged leaf wetness.
  3. Avoid pushing lush growth with unnecessary nitrogen while diagnosis is underway.
Seasonal watch

Conditions matter more than dates.

Warm humid weather and long periods of wet leaves favour disease on susceptible hosts, including some newly established turf.

Inspect during warm wet spells; regional weather and grass variety determine the risk.

Explore your region & month ↗

Can a brown-patch product be assumed to cover this?

No. Match the confirmed disease, grass and use situation to the exact Australian label.

Keep investigating

Similar problems. Different solutions.

Reviewed 11 October 2026 · Turfmate. Seasonal windows are indicative planning guidance, not measured outbreak or prevalence data.

Technical sources & image credits

Photos support identification and may have been taken outside Australia. Appearance varies with species, mowing and conditions. A Turfmate product link does not imply endorsement by a photographer or source.