Lawn & Turf Tips:  Red Thread

Red Thread

Have you ever had a brown patch in your lawn that has a reddish tinge? The reddish tinge is caused by a fungus called red thread or Laetisaria fuciformis. On the tops of the grass blades are little threads or web like strands of red that can extend to around an inch past the height of the grass. It generally doesn't kill the grass but once infected it can kill the grass blade in a matter of a couple of days.

It occurs during the spring and the fall when the weather conditions are more suitable for the fungus growth and dispersal. It happens typically when the temperatures are around 60 degrees-75 degrees outside.

Symptoms

Red Thread most commonly affects red fescue grass and perennial rye grass. Bermuda, bent grass, and Kentucky bluegrass can also be susceptible.

The areas of your lawn that are affected appear to have irregular shaped patches of reddish or pinkish hue to it. It is difficult to identify red thread until the more advanced stages of the disease. This is where the mycelium fungus thread reach a length of 1/16" to 1/4 " at the tips of the damaged grass leaf.

Disease Cycle

• The primary means of dispersal for this fungus is thru the infected tissue and bits of the "red thread" going to the healthy areas of the grass.
• This type of spreading is dependant on mowing, foot traffic, and other activities which occurs on the diseased areas of the turf.
• The fungus spreads quickly and the leaves may even start dying as soon as 2 days after becoming infected.
• The fragmented pieces of the red thread, called hyphae, enable the fungus to survive the unfavorable conditions. During the dry conditions, the threads may be viable for up to 2 years.
  

Control Strategies

Cultural Control

• Maintain adequate fertilization habits. Where the red thread has been a problem you want to maintain a soil pH of 6.5 to 7.0
• Avoid over watering you lawn. You only want to water your lawn 1" - 1 1/2" a week. Do not water your lawn in the late afternoon or evening because this promotes more disease.
• Provide adequate drainage for your lawn through aeration in either the spring or, preferably, the fall.
• Do not let your thatch levels to accumulate. Your thatch should not be thicker than 1/2".

Chemical Control

If the disease is severe, fungicide applications may be necessary.

If you suspect a problem with this in your lawn, please call so we can come take a look at it and advise you on what needs to be done.