Red Thread

Causal Agent: Laetisaria fuciformis

Susceptible Turfgrasses: Cool season turfgrasses.

Symptoms

• Circular or irregularly shaped, small to large patches (5 to 15cm) in diameter of infected grass become water-soaked and die rapidly.

• First symptoms observed is the tan colour of dead leaves.

• Dead leaves are generally interspersed among uninfected leaves giving an overall diffuse, scorched or ragged appearance to the patch.

• Only the foliage is infected and death usually proceeds from the leaf tips downwards.

• Pink to pale red or orange fungal growths (red threads) may extend up to 10mm beyond the leaf tips.

• Pink, cottony flocks of mycelium may be produced.

• When red threads or strands are present, the patched of blighted grass take on a reddish, pink or tan cast that is easily detected.

Conditions Favouring Disease

• Foliar wetness, heavy dews, light rains and fog resulting in more than 10 hours a day of foliar wetness for several consecutive days.

• Thrives in temperatures between 17°C to 29°C.

• Severe when potassium, phosphorus, calcium and nitrogen are deficient.

• Read Thread causes disease primarily during periods when grass is growing slowly as a result of low temperatures, drought or inadequate fertility.

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