If pale, sunken rings and crescents are appearing in your lawn this summer, with the dead bronze grass in the ring slowly being colonised by weeds and coarser grasses, you may be looking at take-all patch, one of the more destructive lawn diseases. The practical takeaway is to act on the cause rather than just the symptom: take-all patch is driven by high soil pH and thrives on limy, alkaline ground, so the most effective treatment is to gently acidify the soil with sulphate of ammonia rather than reaching for a fungicide. Spot it early, by the ring shape and the way bentgrass dies out first, and you can stop it before it spreads into metre wide dead zones.
Take-all patch is caused by the soil fungus Gaeumannomyces graminis, which attacks grass roots. It is most damaging to bentgrasses, the fine Agrostis species common in ornamental and older lawns, but it also affects fescues and meadow grasses. Because it kills the roots, the grass cannot take up water and collapses in patches even when you are watering, which is one reason gardeners often misread it as simple drought stress.
How to Tell Take-All Patch From Drought or Other Diseases
The clearest sign is the shape. Take-all patch appears as roughly circular rings, crescents or arcs, starting small at perhaps a hand span across and expanding in successive years to reach a metre (three feet) or more in diameter. The grass inside the ring turns light brown, reddish or tan and dies back, and the bare centre is then taken over by weeds, annual meadow grass or coarse grasses that resist the fungus. That doughnut pattern, dead ring with a recolonised centre, is the giveaway. It tends to show through late spring and summer and is worst on bentgrass.
Drought damage, by contrast, follows the dry spots of your lawn, the south facing edges, the high ground and the strips over buried rubble, rather than forming neat rings, and it greens up again once rain or watering returns. If you water a brown patch well for a week and it stays dead in a ring while the rest recovers, suspect disease rather than dryness. You can also pull at the affected grass: take-all rots the roots, so infected plants lift away easily with little root left, whereas drought stressed grass stays firmly anchored. Confirming this before you treat saves you from pouring water on a problem that water cannot fix.
It is worth separating take-all patch from the other ring forming problems gardeners meet, because the treatments differ completely. Fairy rings produce dark green, fast growing circles, often with mushrooms, caused by fungi feeding on organic matter in the soil, and the grass in the ring grows more strongly rather than dying. Red thread shows as pinkish red threads binding the leaf blades in irregular patches, not clean rings, and is driven by low nitrogen rather than high pH. Take-all is the one where the ring itself dies back to bare soil and is then invaded by weeds and coarse grass. Reading the pattern correctly is what stops you, for example, feeding nitrogen to cure red thread when the real issue is take-all that needs the soil acidified instead.
Why High pH and Liming Make It Worse
The mechanism behind take-all patch is closely tied to soil chemistry, and this is where most preventable cases come from. The fungus is favoured by soil pH above about 6.5, by recent liming, by the use of alkaline topdressing materials, and by deficiencies of phosphorus and manganese. The disease is also encouraged by wet conditions and by freshly disturbed or newly established ground. In practice this means the gardener who limes a lawn to discourage moss, or who topdresses with an alkaline sand, can unintentionally create the exact conditions take-all needs. The fungus is naturally present in many soils and only becomes a problem when the chemistry tips in its favour.
This is why the standard advice to lime a mossy or acidic lawn should be applied with care. Most fine lawn grasses are perfectly happy at a slightly acidic pH of around 6.0, and keeping the soil there discourages take-all while still growing good grass. Raising the pH towards neutral or above, in the belief that sweeter soil is healthier, can backfire by inviting this disease in.
Newly laid lawns are especially vulnerable, which catches out people who have just invested in fresh turf or a reseed. The fungus colonises the disturbed, low competition soil of a young lawn quickly, and a brand new lawn that mysteriously develops dead rings in its first or second summer is a classic case. Sandy and gravelly soils that drain hard and dry out, then receive alkaline tap water over time, can also drift towards the higher pH the disease prefers. The good news is that take-all patch often burns itself out after a few years as the soil microbe balance recovers and competing organisms suppress the fungus, a process turf scientists call take-all decline. Acidifying the soil and overseeding the bare centres simply speeds that recovery along and limits the damage in the meantime.
How to Treat and Prevent It
The most effective cultural treatment is to acidify the soil back down towards a pH of 5.5 to 6.0 using an acidifying nitrogen fertiliser, and sulphate of ammonia is the classic choice. As the ammonium in it is taken up, it releases a small amount of acid that lowers soil pH while feeding the grass nitrogen at the same time. A 1.25kg tub of sulphate of ammonia, such as the Vitax product, costs around 8 to 10 pounds / 10 to 13 US dollars, while a 25kg sack runs about 20 pounds / 25 US dollars for larger lawns, available at garden centres, Amazon and agricultural suppliers. Apply at roughly 24g per square metre, sprinkled evenly and watered in, and repeat through the growing season as directed to bring the pH down gradually. Do not overdo it, as too much nitrogen in hot dry weather can scorch the lawn.
Alongside acidifying, sow a mixture of grass species rather than relying on pure bentgrass, because a blend that includes resistant ryegrass and fescue reduces how badly the disease takes hold. Correct any phosphorus or manganese deficiency with a balanced feed, improve drainage on wet ground that stays soggy, and avoid liming unless a soil test clearly shows your lawn is too acidic. A simple soil pH test kit costs only a few pounds and tells you whether your lawn is in the danger zone above 6.5. Fungicides are rarely worthwhile for home lawns against take-all, because they are expensive, short lived and do nothing about the underlying pH that caused the outbreak.
Overseeding the dead centres is the step that restores the look of the lawn while the soil chemistry slowly corrects. Rake out the dead grass and debris from each ring to expose soil, scratch the surface lightly, then sow a hard wearing mixture that leans on ryegrass and fescue rather than pure bentgrass, at around 35g per square metre. Early autumn is the best window because warm soil and reliable moisture give fast germination, though a summer reseed will work if you keep it watered with the cycle and soak approach so the young seedlings never dry out. Firm the seed in, keep the area damp until it has knitted together, and the recolonised ring blends back into the lawn within a few weeks.
Caught early, take-all patch is manageable: confirm it by the ring shape and rotted roots, test your pH, and shift the soil gently back towards mild acidity while overseeding the bare centres with a mixed seed in early autumn. Left unchecked on alkaline ground, it spreads outward year on year and leaves a lawn pocked with weed filled rings. For more on soil testing, pH and overseeding worn patches, see the related guides on lawnandmowers.com.
