Red thread disease


  1. Do you see patches (75mm – 1 metre) of tan coloured turf?
  2. Do you see bright red threads in the tan turf?
  3. Do you see these symptoms when it is wet or humid?

If you answer yes to the above questions, you have observed the red thread disease of turf. It is a disease that you can control quite easily.

General description of red thread

The disease red thread is caused by a fungus that lives in your turf. All turf has this fungus in it, it is one of thousands of fungi that live in turf. Normally you do not see the fungus or the disease it causes, but during conditions of high humidity or wetness, it may appear. At first you will notice small patches of your grass leaves turning tan coloured or dying. If you look closely at the leaves, you will notice that they will turn tan, starting at the tips. Fortunately only the leaves are killed, and the turf can grow new ones. A day or so after you see the tan patches, and if the weather stays humid or wet, you will see bright red threads in the patches. You are looking at the fungus.

Info centre - lawn diseases red thread disease

Most people recognise fungi because they produce mushrooms or toadstools, but the red thread fungus produces threads of red material. These fragile red threads can be moved by water, shoes, and lawnmowers, and thus spread the fungus. Red thread attacks ryegrass faster than other types of turf, but because it primarily attacks the leaves, it is generally controllable using some simple guidelines. Red thread is more serious on turf that is not being cared for. It can kill patches of your turf if it is allowed to develop for weeks at a time. It attacks all of the grass species grown for turf in the U.K.

How to manage red thread disease in turf

There are some simple means for reducing the development of red thread, but make sure you actually have the red thread disease before you try and manage it.

  1. If you are installing new turf, ask your turf supplier if the turf they produce has good red thread resistance.
  2. Fertilise your lawn properly.
  3. Water your turf properly, but do not over water.
  4. Mow your grass properly.
Info centre - lawn diseases red thread disease

Can you use fungicides to control red thread?

Yes, there are fungicides approved for use to control red thread disease. It is recommended that before you use a fungicide, you make certain that you have the red thread disease in your turf, and that you consult a turf expert on the use of fungicides. STRI UK is the world’s leading sports turf consultancy, you can visit their website Generally, if you take proper care of your turf you will rarely need to use a fungicide. We also recommend that you obtain advice about chemical and non-chemical products direct from the manufacturer.


Red thread develops in lawns that are poor in quality or generally receiving too little fertiliser. Manage your turf properly, and red thread will not be a common problem for you.