Lawn Disease

Lawn Disease

Red Thread, Fusarium, Leaf Spot, Dollar Spot, Anthracnose and Rust are all lawn diseases. They can all affect the grass plant causing discolouration, weakening the plant and ultimately killing it altogether. Most of these diseases are caused due to stress on the lawn - whereby the plant is not being cut correctly, it is not receiving sufficient water, thatch levels are too high or the lawn is suffering with compaction. The environment can also play a part, for example humidity will affect the plant along with too much water sitting on the leaf of the plant. Control is achieved by using either a fungicide or correcting some of the issues that cause the disease by cultural means.

Diseases in lawns are commonly caused by the presence of a fungus and are often termed pathogenic agents of disease. Many disease pathogens are already present either in the thatch or basal leaf, awaiting the right conditions to break out. The disease known as Red Thread has a fungus called Laetisaria fuciformis, Fusarium has the fungus known as Michrodochium nivale.  These are the most common of lawn diseases we find in UK lawns, there are many others, some as listed above. The treatment of these diseases can be related to their cause; the cultural process is probably best for the plant, if it works successfully then the lawn is fully restored without the use of products that may be best saved for when the cultural process has been ineffective.

The sprayed product we recommend is taken from other fungi to act as an agent to protect the plant; the product works its way into the plant via the leaf and root system; it will control the disease for generally about one month. If the cultural processes have been followed then it is likely that you will have control for a longer period of time. We have two different control measures, one for the growing season and the other for when the plant is dormant.

Having a good programme of lawn care i.e. regular feeding, weed control, aeration, scarification and moisture control, along with good cutting practices, will help to keep the lawn balanced and reduces the risk of disease.

Snow Mould

Closely related to Fusarium is Snow Mould, another cold weather disease that thrives in lawns with poor air circulation. This fungal disease spreads rapidly during cold weather, especially under a blanket of snow, when air circulation is impossible. When snow settles on a lawn for any length of time, it incubates the disease which can only be seen once the snow has melted away.

The fungus produces white patches which, in severe cases, can turn pink. To avoid this disease, try and keep snow off the lawn. If this is not possible, it can be treated with a special fungicide.

Fusarium Patch

Fusarium Patch is another very common lawn disease, seen mainly, but not exclusively, during the autumn and winter months. This is a cool weather disease and enjoys persistent drizzle and foggy/misty conditions.

Symptoms appear as small, circular, yellow patches which spread up to about 30cm in diameter. Once established, the patches turn a yellow/brown colour and in severe cases can kill the grass. After the disease becomes inactive, the area appears pale and straw-like.

Lawns that have a high thatch layer and poor drainage, as well as enclosed lawns with little air movement, are the most susceptible to Fusarium.

Leaf Spot

Leaf Spot is a very common lawn disease that affects lawns across the UK. It can also be known as leaf blight or net blotch. The disease can be caused by a number of different fungi and spreads rapidly. Warm and humid weather conditions are favoured by this disease and spores of the fungi are disseminated by water splash.

A stressed plant is more likely to be affected than a healthy one, so ensuring the grass is well fed and watered will help. Also ensure the mower blades are sharp and do not cut the grass too short. If the lawn suffers from thatch, consider having the lawn aerated to ensure adequate drainage.

There are other pests that you may come across, and your local operator will be able to advise you accordingly.

Fairy Rings

Fairy rings can be found in turf all over the world. This lawn disorder can be seen as complete circles, ribbons or arcs of stimulated grass growth, which may or may not be associated with bare areas of turf and toadstools.

There is not always a specific reason as to the cause of a fairy ring, although very often it is caused by rotting wood or root in the soil. As the wood rots down it develops mycelial spores that work their way up to the turf surface.

The mycelium then becomes hydrophobic which makes the soil water resistant and this exacerbates the problem. Fairy rings are very difficult to treat, but if you have this problem, we will be happy to advise and recommend a 
course of treatments.


This is possibly one of the oldest known turf diseases. It attacks the leaf plant and causes extensive damage. It rarely attacks the whole plant, so recovery is usually good.

This disease thrives on plants suffering from stress, and is most prevalent in autumn or early spring, when the weather is warm and wet.

If your lawn is looking under the weather, tired and not the right colour, speak to your local GreenThumb expert who will be able to offer solutions and great advice.

Red Thread

Red Thread can be seen throughout the summer months during periods of high humidity. The occurrence of the disease is most evident after periods of wet weather, especially towards the end of summer, when humidity is high.

The lawn will begin to show small patches of grey-brown turf initially; on closer inspection the grass plant will have small, red ‘needles’ protruding from the diseased leaf.

Although high humidity is the main cause of Red Thread, it can also be seen in lawns that are suffering from plant stress. This is usually caused by: Poor cutting regime, drought, thatch, compaction, lack of feeding.

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  •  "I am a relatively new customer but I wish to thank you for the great job you have done on my lawns. In six months they have gone from green/yellow to a lush green appearance with few weeds and moss. Well done GreenThumb from a very satisfied customer."

  • "We've now had two treatments from your service. Already we have noticed a difference in the quaility of the lawn and the greenness. Really pleased. Also, the young men who have visited have been charming - very polite and pleasant, thank you."

  • "When we moved into our house five years ago, the whole garden was very overgrown and the lawns were in a dreadful state. After only two years our front and back lawns have been dramatically transformed, I would highly recommend GreenThumb to anyone."

  • "We bought a new property and the land had previously been used as a pig farm so lots of strong weeds. We are now a year in from the start of your team's treatment and the improvement is 200%. The team in Norwich always arrive on time, are courteous and are very well informed."

  • "The grass is lush, thick, green and plentiful. Even the front which was an eye sore has received compliments. We are delighted with what has already been achieved and only wish I had known about this service sooner. I could have saved myself a lot of time and effort."