DISEASE

ANTHRACNOSE

Susceptible Turfgrasses: Wintergrass, Bentgrass, Kentucky Bluegrass, Fescue & Couch

Symptoms

  • Leaves of infected plants turn yellow to a light tan to brown before dying.

  • Younger leaves often turn red.

  • Basal stem and leaf sheath rot, affected plants are easy to pull out.

  • Infected areas are seen as irregular shaped patches.

  • Affected patches are a reddish brown colour turning yellow then tan to brown.

  • A black stain may occur at the base of infected plants, this is an acervulus, a black fungal fruiting body.

Conditions Favouring Disease

  • Disease development is favoured by warm humid conditions.

  • Anthracnose favours temperatures over 25°C.

  • It is necessary for a film of moisture to be present on either the roots or foliage for infection to occur.

  • More than 10 hours a day of leaf wetness for consecutive days.

  • Hot summers in cool temperature areas are when the disease is most noticeable.

  • Soil compaction and low amounts of nitrogen also contribute to disease occurrence.

BIPOLARIS

Susceptible Turfgrasses: Warm season turfgrasses.

 

Symptoms

  • Irregularly shaped brownish green to black lesions may appear.

  • Severely infected leaves begin to die back turning tan to dark brown.

  • Irregularly shaped patches of infected foliage may range from 5cm to 1m in size.

  • Chlorosis may occur in infected foliage before the leaf turns brown.

  • Extensive crown and root rot may occur in severe infections.

  • Plants may lose vigour, becoming weak and flaccid.

Conditions Favouring Disease

  • Foliar blight and lesions occur during cool, wet periods from autumn to spring.

  • Crown and root rots may occur in warm humid weather throughout summer.

  • Possesses a wide temperature range of activity depending on the Bipolaris species.

  • More than 10 hours a day of leaf wetness for several consecutive days.

  • Poor air movement (high humidity in the micro-climate).

  • Excessive nitrogen fertiliser.

  • Excessive thatch and loose leaf clippings provide a source of food for the fungus.

  • Any stress situation such as drought, herbicide injury or heavy traffic can increase the severity of the disease.

BROWN PATCH

Susceptible Turfgrasses: Wintergrass, Couch, Bentgrass, Fescues, Kentucky Bluegrass, Ryegrass & Buffalo Grass.

Symptoms

  • Brown discoloured circular patches, from a few centimetres up to a metre in diameter, sometimes with a smoke ring of mycelium around the edges.

  • “ Smoke rings” appear as thin brown borders around the diseased patches appearing in the early morning.

  • Infected leaves are water-soaked and dark, later dying and turning dark brown.

  • After the infected leaves die, new leaves can emerge from the surviving crowns.

  • On wide bladed species, leaf lesions develop with tan centres and dark brown to black margins.

 

Conditions Favouring Disease

  • High relative humidity and temperatures of over 28°C during the day and over 15.5°C at night.

  • More than 10 hours a day of foliar wetness for several consecutive days.

  • Turfgrass species are most affected when night temperatures are consistently above 20°C with high humidity or moisture.

CURVULARIA LEAF SPOT

Susceptible Turfgrasses: Wintergrass, Kentucky Bluegrass, Bentgrass, Fescue, Couch.

 

Symptoms

  • Individual leaves initially show yellow and green dapple patterns that extend downwards from the leaf tip.

  • Infected leaves turn brown, then grey as they shrivel and die.

  • Irregular shaped patches of thinned turf appear, often coalescing to affect larger areas.

  • Stolons and leaf sheaths may also rot.

 

Conditions Favouring Disease

  • Curvularia Leaf Spot occurs in areas that experience prolonged leaf wetness for several consecutive days.

  • Curvularia occurs at temperatures, 25 to 35°C.

  • Soil compaction and excessive levels of nitrogen and thatch.

DOLLAR SPOT

Susceptible Turfgrasses: All turfgrass species, predominantly cool season grasses.
 

Symptoms

  • Small, sunken, circular patches 1.5 to 5cm in diameter.

  • The patches turn from brown to a straw colour and may eventually coalesce, into larger irregularly shaped areas.

  • In the presence of dew, mycelium may be seen as a fine white cottony thread.

  • Infected leaves may display small lesions that turn from yellow-green to straw colour with a reddish-brown border.

  • Lesions can extend the full width of the leaf.

  • Multiple lesions may occur on a single leaf blade.

 

Conditions Favouring Disease

  • Temperature ranges of 16°C to 28°C and continuous high humidity above 85%.

  • Warm humid weather with cool nights that produce heavy dews.

  • When the micro-climate temperature reaches 16°C the fungus resumes growth.

  • Low nitrogen levels.

  • More severe in dry soils.

FAIRY RING

Susceptible Turfgrasses: Occurs in all turfgrasses.

 

Symptoms

  • Fairy Ring symptoms vary with causal agents (fungal species).

  • Circular or arc shaped rings of darker or faster-growing turf appears in moist turf.

  • A concentric ring of dead grass may develop inside the circle of lush grass.

  • The size of the rings can vary from a few centimetres to indefinitely large.

  • Activity in the turf stops when the individual rings come into contact with each other.

  • Mushrooms or toadstools may be produced in the outer ring of lush growth.

  • As mycelium grows the soil becomes hydrophobic.

  • In a mature Fairy Ring, the outer ring of lush grass may be missing, leaving an outer ring of plant death and an inner ring of green turf.

 

Conditions Favouring Disease

  • Fairy Rings are more severe on light soils, which have low fertility and low moisture content.

  • Turf with a significant thatch layer.

  • Drier areas have significantly more Fairy Rings than higher rainfall areas.

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