Red Thread
Causal Agent
Laetisaria fuciformis
What is red thread disease?
Red thread is a fungal disease that affects turf and lawns. The first symptoms of red thread disease is often the tan colour of dead leaves. Pink, pale red or orange fungal growths may extend up to 10mm beyond the leaf tips, giving red thread disease its name. When these red threads or strands are present, the blighted grass take on a reddish, pink or tan cast that is easily detected.
What are the symptoms of red thread disease?
Red Thread disease is particularly difficult to diagnose when red threads or cottonly strands are not present. General symptoms of red thread include:
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Circular or irregularly shaped, small to large patches (5 to 15cm) in diameter of infected grass become water-soaked and die rapidly.
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First symptoms observed is the tan colour of dead leaves.
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Dead leaves are generally interspersed among uninfected leaves giving an overall diffuse, scorched or ragged appearance to the patch.
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Only the foliage is infected and death usually proceeds from the leaf tips downwards.
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Pink to pale red or orange fungal growths (red threads) may extend up to 10mm beyond the leaf tips.
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Pink, cottony flocks of mycelium may be produced.
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When red threads or strands are present, the patched of blighted grass take on a reddish, pink or tan cast that is easily detected.
Red Thread INFO SHEETWhat turfgrasses are particularly susceptible to red thread disease?
Cool season turfgrasses.
When does red thread disease occur?
Conditions that are particularly favourable to red thread are:
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Foliar wetness, heavy dews, light rains and fog resulting in more than 10 hours a day of foliar wetness for several consecutive days.
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Thrives in temperatures between 17°C to 29°C.
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Severe when potassium, phosphorus, calcium and nitrogen are deficient.
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Read Thread causes disease primarily during periods when grass is growing slowly as a result of low temperatures, drought or inadequate fertility.
What can I do to manage or control Red Thread disease?
Turf management practices that can help control or reduce instances of red thread include:
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Mowing turf frequently and collect clippings to remove diseased portions of the leaves.
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Maintaining adequate nitrogen and a balanced fertility.
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Applying moderate to high amounts of phosphorous and potassium.
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Maintaining the soil pH between 6.5 to 7.0.
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Reducing shade and Increasing the air circulation to the turf.
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Irrigating turf deeply and as infrequently as possible. Avoid frequent watering in the late afternoon.
