Turfmate field notes · Diseases

Anthracnose

Colletotrichum species

Yellowing and crown decline in stressed fine turf need close examination.

Extensive anthracnose basal rot damage on an annual bluegrass putting green.
Extensive anthracnose basal rot damage on an annual bluegrass putting green.
Photo: Pete Dernoeden, Ph.D / Syngenta GreenCast · Full photo ↗

What to look for

  • Irregular areas lose colour, progressing from yellow to tan or brown.
  • Inspect the stem base and leaf sheath for dark discolouration.
  • A microscope can reveal the characteristic fungal structures.

More photos to compare

Compare the overall pattern with the plant detail. Check the grass species and growing conditions as well as the appearance.

Darkened stem bases associated with anthracnose basal rot.
Darkened stem bases associated with anthracnose basal rot.
Photo: S. McDonald / Syngenta GreenCast · Full photo ↗
Early yellow and bronze flecks associated with anthracnose on annual bluegrass.
Early yellow and bronze flecks associated with anthracnose on annual bluegrass.
Photo: Pete Dernoeden, Ph.D / Syngenta GreenCast · Full photo ↗
View an additional reference
Field symptoms of basal rot anthracnose of turfgrass, from the University of Wisconsin-Madison diagnostic collection
Field symptoms of basal rot anthracnose in turfgrass. University of Wisconsin-Madison diagnostic lab reference; the source does not specify the grass variety or exact site.
Photo: Paul Koch, Turfgrass Diagnostic Lab, University of Wisconsin-Madison · CC BY-SA 3.0. Original file; no edits.

Confirm it before you treat it

Poa and bentgrass greens deserve particular attention. Pythium and heat stress can resemble this disease; send a fresh sample for diagnosis.

What to do next

  1. Reduce wear on affected turf and avoid disruptive renovation during active disease.
  2. Review balanced nutrition, irrigation and prolonged leaf wetness.
  3. Use a confirmed diagnosis to plan treatment and resistance management.
Seasonal watch

Conditions matter more than dates.

Warm, humid conditions and stressed turf increase the need for monitoring. Site conditions matter more than a fixed month.

Is a yellow patch enough to confirm anthracnose?

No. Inspect individual plants and seek laboratory confirmation before choosing a fungicide.

Laboratory references

Look beyond the brown patch.

These magnified references show fungal structures used during diagnosis. A patch photograph alone does not confirm anthracnose; fresh plant samples and professional examination may be needed.

Magnified view of dark anthracnose fruiting structures, called acervuli, on plant tissue
Magnified anthracnose fruiting structures (acervuli) on plant tissue, from the turf diagnostic lab collection. This is a laboratory reference, rather than a view of the lawn at normal scale.
Photo: Paul Koch, Turfgrass Diagnostic Lab, University of Wisconsin-Madison · CC BY-SA 3.0. Resized from original; no other edits.
Microscope view of conidia, or spores, of crown rot anthracnose of turfgrass
Microscope view of crown-rot anthracnose spores (conidia) from turfgrass. The source does not state the magnification; these spores cannot be identified in an ordinary lawn photograph.
Photo: Paul Koch, Turfgrass Diagnostic Lab, University of Wisconsin-Madison · CC BY-SA 3.0. Resized from original; no other edits.

Reviewed 11 October 2026 · Turfmate. Identification guidance is not a laboratory diagnosis or a spray calendar.

Technical sources

Syngenta photographs are reproduced in full with attribution. Source grass species and settings are identified where supplied; photographs support identification and do not replace diagnosis.

Syngenta Australia: Anthracnose