Red Thread Disease: Pink Patches in Your Lawn Explained
Pink, cottony patches with coral-red threads are a sign of red thread disease — the most common turf disease in the UK. Learn what causes it and how feeding your lawn clears it up.
Diagnose the Problem
Red thread disease is one of the most common turf diseases in the UK, caused by the fungus Laetisaria fuciformis. The good news is that it's rarely serious: it almost never kills grass outright and usually leaves no permanent damage, even though it looks alarming. It's the classic 'pink patches in the lawn' that prompt a phone call.
Pale pink, irregular patches
During the growing season, affected areas of turf turn a washed-out pink or bleached straw colour in uneven, patchy shapes. Grass leaves in these areas die and become matted together by fungal growth.
Pink fluff and coral-red threads
The giveaway is the fungal growth itself — small pink fluffy tufts, or coral-red needle-like outgrowths on the leaf tips, which give the disease its name.
Low nitrogen availability
The single biggest trigger. Red thread is strongly associated with underfed lawns and low soil fertility, and the dead leaves that come with it feed the problem further.
Susceptible grass species
Perennial ryegrass and red fescue — the two species most commonly used to produce UK turf — are frequently infected, so a brand new lawn can show it.
The right weather at the wrong time
Spores of the fungus are present everywhere in the soil and air. A lawn can be attacked whenever the weather suits it, even when everything has been done properly.
The Solution
Because red thread is a symptom of a hungry lawn, nutrition is the treatment. Feed the grass and the disease normally fades out on its own within a few weeks — a fungicide is rarely needed.
Confirm it's red thread
Look for pale pink, irregular patches with matted leaves, plus pink fluffy growths or coral-red needle-like threads at the tips of the grass. If you can see those threads, it's almost certainly red thread and not drought or grub damage.
Feed the lawn with nitrogen
Apply a high-nitrogen lawn fertiliser — a spring/summer feed such as 9-7-7 at around 35g per m² is ideal — and water it in if no rain follows. This is the most effective control there is: stronger grass growth crowds the disease out and new leaves replace the dead ones.
Use a pre-turfing fertiliser on new lawns
If you're laying new turf on a site with poor or thin soil, work a pre-turfing fertiliser in beforehand to prevent red thread developing while the turf is rooting. Once it has rooted and established, keep up an occasional feed as part of your normal routine.
Improve the soil beneath the turf
Healthy turf starts with healthy soil. Aerate compacted areas and improve drainage so the rootzone is well-structured and free-draining — disease pressure is far lower on turf that isn't sitting in poor, airless soil.
Don't reach for fungicide
Chemical control is usually unnecessary. Red thread rarely kills grass outright and the affected patches recover as the lawn grows back through, so a fungicide is only ever worth considering on fine, high-value turf — and even then it treats the symptom, not the low fertility behind it.
Repair any thinned areas
If a patch has thinned badly, rake out the dead material and overseed with a quality grass seed blend once the disease has passed. Keep the lawn fed afterwards so the new grass establishes strongly.
Use the Fertiliser Calculator
Work out exactly how much high-nitrogen fertiliser your lawn needs to grow out of red thread.
Recommended Products
Shop high-nitrogen lawn feeds to clear red thread, plus grass seed to repair any patches that have thinned.
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