Red Thread

Red Thread – Laetisaria Fuciformis – is a fungal disease which attacks grass. It appears as irregular patches of light, brown grass which have a reddish hue. On closer inspection a small red spike can be seen protruding from the tip of the affected blades. The roots are not affected and the grass usually recovers well, so although unsightly, the damage to the lawn is slight, and is only present for a relatively short period.


Infection occurs during periods of soil humidity, when the air temperatures are warm, and the sub soil is cooler ( or vica versa during periods of prolonged rainfall ) . The infection also arises because of a lack of nitrogen in the soil resulting in a sub soil chemical imbalance.

The application of a suitable fertiliser during the growing season is the best means of prevention and cure, and a fungicide spray can also be of help if the problem continues, but this is an expensive alternative. The grass roots usually regenerate top stem growth and the Red Thread will disappear as the new growth develops over a period of 3 – 4 weeks. If the area becomes so affected that the grass dies off completely, then rake out the dead grass and cover the area with a Top soil and seed mix, remembering to apply light water to all repaired areas each day for 10 days on any day without meaningful rainfall.

Do not leave mower cuttings on the lawn, as this can spread the disease to other areas of the lawn.