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Anthracnose

Anthracnose
Caused by: Colletotrichum graminicola (Ces.) G. W. Wils.

Plate 1: Anthracnose foliar blight

Description
Anthracnose is most common on Poa annua grass in the UK and Ireland but has been noted on Agrostis and Fescue. This pathogen can cause two types of disease depending on the prevailing weather conditions.

Foliar blight is often mistaken for drought. The grass turns a tan-yellow colour in irregular patches (Plate 1). The presence of acervuli with hair-like setae is used to microscopically diagnose foliar blight (Plate 2).

Basal rot begins as yellowing of older leaves on individual plants. The youngest leaf may become brick red in the later stages of development. The plant easily pulls from the turf and a black rot is visible at the base of the stem.

Basal Rot also occurs during the late summer and is normally most damaging during August and September, although sometimes symptoms are also seen  through the autumn and winter.

Plate 2: Acervulus with setae visible with a microscope.

Where is Anthracnose found?
Any area of turf suffering from stress, especially golf greens, tees and fairways, bowling greens and sports pitches. Anthracnose is widespread over the whole of the UK. It is the second most common disease on golf courses in the UK and Ireland.

When is Anthracnose likely to attack turf?
Foliar blight is most common during hot, dry periods of the summer. Basal rot is mostly found during cool, wet weather from late autumn through winter and into early spring.

Effects of Anthracnose
Infection with anthracnose reduces the playing quality of golf and bowling greens as the surface trueness is reduced. In severe cases (especially with foliar blight), loss of turf cover may occur, which may encourage the ingress of more Poa annua grass.

High Risk Situations
Presence of Poa annua. Turfgrass that is under stress. Common stresses include drought conditions, compacted soils, areas of high wear, inadequate nitrogen, potassium or phosphorus, insect or nematode feeding, damage to grass plants caused by fungal pathogens and excessively low cutting heights.

Integrated Turf Management

  • Reduce the ingress of Poa annua grass intoAgrostis/Festuca swards.
  • Accurately identify the disease (refer to photos and STRI diagnostic service).
  • This is especially important for foliar blight if the problem has been misidentified as drought. Irrigation applied to relieve drought will be conducive to the spread of anthracnose rather than solve the problem.
  • Increase the height of cut.
  • Alleviate compaction.
  • Apply a nitrogenous fertiliser if the fertility is low.
  • Avoid a moist or humid turf surface and dry soil by applying infrequent, deep watering.
  • Regularly look at GreenCast to identify periods of high risk.

Fungicidal Control
Preventative applications provide optimum control of anthracnose. The following products have label recommendation for anthracnose control in the UK:

  Banner Maxx Heritage Maxx
Mode of action Systemic Systemic
Optimum timing During conducive conditions During conducive conditions
Dose rate 3.0 l/ha 2.5 l/ha
Water volume 400 to 1000 l/ha 125 to 500 l/ha
LERAP N/A N/A

Suggested Programme
Once conditions conducive to anthracnose occur, or Greencast indicates high risks of disease a preventative application of either Heritage or Banner Maxx should be applied.

This should be followed approximately 14 to 28 days later with an application of Instrata if weather conditions have remained conducive (use Greencast to determine the risk).