Red Thread Disease & Treatment: Questions and Answers

1st Aug 2014

With the great weather we have had over the past few weeks, mixed with humidity and doses of heavy rainfall, the perfect conditions have occurred for Red Thread disease. We’ve had customers all across the country asking us different questions about the disease.

We’ve decided to make a detailed post with answers to some of the most common questions we receive, as well as putting the facts straight about what Red Thread really does and does not do to your lawn.

So What is Red Thread exactly and what are the main symptoms?


Red Thread is a common turf disease, caused by fungus in the soil. Believe it or not, the fungus that causes Red Thread actually exists in most soils. It’s just that its normally below the turf level so you can’t normally see it.

The first noticeable symptoms will be brown patches of grass that start to appear. To the untrained eye, these patches may simply appear to be dead grass. Closer inspection is usually required to identify whether its Red Thread or not.

If you get down close to the grass, you will notice very small red “threads” wrapped around the grass leaves (hence the name Red Thread) These threads are the result of the fungus. Sometimes, small pink cotton-like areas will be noticeable when looked at closely. These are parts of the mycelium fungus. If you want to see them more clearly, place them onto a white piece of paper.

From a distance, an infected lawn will simply appear brown and patchy. In extreme cases of Red Thread, you can actually see the threads from a fairly large distance. The lawn will have a patchy red tinge to it.

How does Red Thread really affect my lawn?

Apart from the visual disturbance, Red Thread doesn’t cause as much damage as most people think, it’s mainly just a sight for sore eyes. It attacks the grass leaves, but not the roots, therefore it very rarely actually kills grass.

The grass will turn brown as a result of attacking the leaves, but this will wear off once conditions become unsuitable for the Red Thread to remain established in.

For a strong and continuos infestation of Red Thread, temperatures of 17-24C are required. The disease will normally occur from spring and autumn, but can occur throughout the year if conditions remain suitable, especially in later summer.

Why does Red Thread appear in some lawns and not in others?

When the weather conditions are suitable for Red Thread, the other main factor that will determine how widespread it becomes is the type of grass you have. The disease is primarily a fine fescue grass disease and will rarely appear in lawns that are predominantly ryegrass.

Bent grasses and annual meadow grass (Poa-annua) can be affected, but again fescues are the main affected grasses. The disease has continuously developed over the years and there are now hundreds of strains that can occur.

What can I do to help stop the disease spreading so much?

There are various best practices that can be followed in order to help stop Red Thread occurring, or at least minimise the spread of the disease, such as:

  1. Always clean off your lawn mower blades if you’ve cut one of your lawns that has Red Thread. The disease can be spread by your blades carrying it to other lawns.
  2. The same as above needs to be said if you have a gardener cutting your lawn or if you are using a lawn cutting service.
  3. Rotating fertilisers used on your lawns. If you treat your lawns yourself, it’s important not to use the same fertilisers repeatedly.
Common misconceptions and other helpful tips

The most common misconception without doubt is that low nitrogen input is the reason why Red Thread occurs, and therefore increasing your nitrogen input will fix the problem. This is not the case. If you consistently apply high nitrogen feeds to your lawns, the disease can fail to respond to other treatments.

Too many people (and companies) immediately resort to a high nitrogen feed as a quick fix solution. We continuously see where this has happened and the problem is only made worse in the long run.

If you use a lawn maintenance company to feed your lawn, you may be surprised to hear that it’s actually very difficult for most of them to change their feed programmes and applications accordingly. The reason being is that they are normally only supplied with a couple of different fertilisers throughout the year which are purchased in bulk.

You therefore need to ask your local lawn care provider. If they have a preset plan for your lawn, this won’t help your lawn fight off the disease. Your lawn should be receiving a bespoke programme of treatments. We are very proud of the fact that we are one of few companies that tailor a lawns requirements like this.

Another misconception is that a fungicide will remove Red Thread. This is not necessarily the case. Fungicides can be beneficial when used early in the year as a preventative as they can help stop the spreading and development of the disease later in the year. However, choosing the correct fungicide is essential and they must be applied at the correct application rate to work properly. The downside of fungicides is that they are expensive, therefore most people choose not to apply them.

More Help and Advice

When you research online for information about lawn diseases, it can be difficult to tell whether they are coming from a reputable source. The answers in this post have come first hand from our greenkeepers and groundsmen, who have spent years of their lives dealing with diseases on professional grounds and pitches.

If you’re a Lawn Master customer, feel free to discuss your lawn with your local outlet owner. They will tell you the best ways to keep your specific lawns under control from the disease as best as possible.

Just remember that all lawns and grass varieties are different, therefore having one solution for all lawns just isn’t a realistic approach. We can’t detail our exact methods here, but as discussed, please contact your local lawn care outlet.

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For over 22 years Lawn Master has been providing professional turf care services and expanding across the UK with a big difference.

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