Expert Advice

Red Thread


Symptoms of red thread include the grass turning a light tan to pink in colour and areas are 2 inches up to 3 feet in diameter. As the blades dry, the pink threads 1/4 to 3/4 on an inch long, protrude from the diseased leaf tips and the pink webs bind the grass blades together. This lawn disease is caused by a fungus and most serious in fine fescue lawns, but can also affect ryegrass, bent grass, and bluegrass lawns. Red thread attacks the leaves and the leaf sheaths, but thrives in wet/moist conditions as well as in lawns with nitrogen deficiency.


Increasing nitrogen fertilization will help reduce red thread damage, and will also encourage plants to recover quickly. Reducing extended periods of leaf wetness by watering deeply but infrequently to wet the entire root zone will also lessen the severity of this disease. The lawn should be irrigated early in the morning, between 4am-7am with 1” of water, once a week. Proper mowing is also very important, you should never cut more than 1/3 of the grass blade off at any time to avoid shocking the grass plant. Keep your lawn around 3” long to make sure your grass doesn’t start using its food reserves, which will impact how quickly it recovers.