The most common lawn diseases in the UK can spell disaster for our grass – but if you know how to spot them and step in before they spread, the damage is usually reversible.
As a gardener, one of the worst feelings is spending lots of time curating your favourite lawn ideas only to have them ruined by a mysterious fungal disease.
Thankfully, many of the most common lawn diseases in the UK are easy to identify, often carrying hallmark symptoms, and they can be corrected with the right know-how. These are the lawn diseases you’re most likely to encounter here in the UK – and how to spot and treat them before it’s too late.
What you’ll need
Nitrogen deficiency is a common theme among the lawn diseases on this list, so a nitrogen-rich lawn fertiliser is a must.
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1. Red thread
Red thread is among the most common lawn diseases in the UK. It usually manifests as pale or straw-coloured grass, and even though it doesn’t exactly look red, it can appear faintly pink.
‘Red thread is a very common fungal disease, particularly in spring, when the weather tends to be mild and damp,’ says Jonathan Davis, grass expert at Lawnsmith.
Weather changes can invite this disease into your garden, but it’s more likely to crop up if your lawn is already in poor condition. You’ll need to gather all the lawn care tips you can if you want your grass to overcome the disease – and even though we’re out of the active season for red thread, bolstering your lawn’s natural defences now will keep the fungus at bay later in the year.
‘It’s usually caused by low nitrogen levels in the soil, so applying a nitrogen-rich fertiliser can usually cure the disease,’ Jonathan explains. ‘Regular mowing in spring and good lawn maintenance can keep it at bay. Very rarely does red thread cause irreversible damage. Once the lawn’s nutrient levels are corrected, the grass typically recovers well.’
Miracle-Gro Lawn Builder, which you can buy from Amazon, is a brilliant high-nitrogen lawn fertiliser that can be used from March.
2. Leaf spot
Leaf spot doesn’t just affect regular plants in the garden – it’s a fungal disease that can target grass, too, often identified by small, dark spots on individual blades. The spots are usually brown, black or purple, and Cheryl says they can join together over time, causing thinning or even dead patches of grass.
Overwatering is one of the worst lawn care mistakes you can make for several reasons, and leaf spot is one of them.
‘It tends to thrive in warm, humid conditions and is more likely in lawns that are overwatered, cut too short or lack good airflow,’ explains Cheryl Harper, managing director of Greensleeves Lawn Care.
Like red thread, leaf spot is best treated by improving general lawn care first.
‘Raising the mowing height to 25-35mm or higher, avoiding late-day watering and improving air circulation can make a significant difference,’ says Cheryl.
‘In more persistent or advanced cases, professional fungicide treatment may be recommended, followed by overseeding to restore damaged areas.’
Thankfully, learning how to overseed a lawn is really straightforward, and packs like the new Westland PureGreen Lawn seed, which you can buy from Amazon, can give a lawn a total refresh.
3. Snow mould
Snow mould is about as unpleasant as it sounds – if you spot white fungus on your grass, it’s likely that Fusarium is the culprit.
‘Fusarium, also known as snow mould, is another common issue, especially in autumn and winter, as it thrives in cool, wet conditions,’ says Jonathan. ‘It appears in small circular patches of yellow, brown or orange grass, and you might see white cottonwool-looking fungal growth.
The best treatment involves improving lawn drainage, because according to Jonathan, ‘Poorly drained, thatchy lawns with limited air circulation are breeding grounds for this fungus.’
It’s worth learning how to aerate your lawn if it’s compacted, and reducing thatch by learning how to scarify your lawn. The 2-in-1 Vonhaus scarifier and aerator from Amazon takes a lot of the effort out of both tasks.
‘Severely damaged areas may need to be re-seeded in spring once growing conditions improve,’ Jonathan adds.
4. Lawn rust
Lawn rust is another common lawn disease in the UK, and as you’d expect, it causes yellow-looking grass. It’s often down to a rust-coloured powder that you might find on shoes, pets or your lawnmower.
‘It commonly develops when grass growth slows due to nutrient deficiency, low light or water stress, particularly when damp conditions follow,’ explains Cheryl. ‘While it may seem like a cosmetic issue at first, rust weakens the grass and leaves it more susceptible to further problems.’
You guessed it – the best first step is to improve your grass’s overall health.
‘Applying a nitrogen-rich fertiliser, improving light levels where possible and maintaining regular mowing will usually allow the lawn to grow out of the infection,’ says Cheryl. ‘Avoid cutting the grass too short during this time, as a slightly higher mowing height supports recovery and reduces further stress.’
There’s always the question of whether or not you should leave grass clippings on your lawn, but Cheryl says it’s wise to remove them when rust is active to limit the spread of spores.
5. Damping off
Damping off is the most common lawn disease that affects freshly-sown grass – so if you’ve just overseeded or reseeded your lawn, it could be at higher risk. It’s a fungal disease that often affects other plant seedlings, too (it’s usually a cause of seeds not germinating), and it often happens when conditions are cool and damp, or the soil around the seeds is too wet.
‘The disease occurs in two forms: pre-emergence damping off, where seeds rot in the soil and fail to germinate, and post-emergence damping off, where seedlings sprout but then collapse at the base, often appearing water-soaked and sometimes covered with a white fungal growth,’ explains Chris McIlroy, lawn expert at The Grass People.
Chris says there’s no cure once damping off takes hold of grass seedlings, so prevention is crucial.
‘Avoid overseeding too densely, ensure good drainage, reduce excessive watering and improve airflow,’ he advises.
6. Dollar spot
Dollar spot sounds like something you’d find overseas, but it’s very much an active lawn disease in the UK. If you spot small, coin-sized spots on your lawn (usually the colour of straw), there’s a good chance the fungus has infiltrated your grass. The spots will grow larger if they aren’t treated.
‘It is caused by the fungus Sclerotinia homoeocarpa and most often develops in lawns that are undernourished, particularly those lacking nitrogen,’ says Cheryl. ‘Poor drainage, excessive thatch and prolonged moisture sitting on the grass can all increase the risk.’
Above all else, you’ll need to address potential nitrogen deficiencies with a fertiliser like Miracle-Gro Lawn Builder from Amazon. It’s also important to work out the best time to water your garden – and when dollar spot is in the picture, Cheryl says morning watering helps reduce surface moisture overnight. Aeration and scarification are also worthy steps, and again, you should avoid scalping your lawn.
‘In more severe cases, targeted professional fungicide treatment may be required, followed by overseeding to restore a healthy, even finish,’ Cheryl adds.
7. Fairy rings
When I first heard about fairy rings, I thought they sounded like whimsical, fun things to have in the garden – but they’re actually caused by a soil-borne fungus that feeds on organic matter on the lawn’s surface, according to Jonathan.
‘They often appear as dark green rings, arcs of dead grass covered in moss, or circles of mushrooms,’ he explains. ‘They are a common sight in late spring right through to autumn, thanks to warm, moist conditions, but can exist all year round.
It’s tricky to get rid of fairy rings because the fungus lives deep in the soil, but Jonathan says improving soil aeration, reducing thatch and watering consistently can keep things at bay.
‘Some severe cases might need an intensive soil treatment to break up the fungal growth,’ Jonathan adds.
Use this guide to the most common lawn diseases in the UK to keep on top of any creeping fungal infections.
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