Take-all is a fungal disease of lawns, particularly those with a high percentage of fine bentgrasses (Agrostis spp.). It causes brown patches of grass, most often in summer when the turf is under drought stress.
What is take-all patch?
Take-all patch is caused by a fungus, Gaeumannomyces graminis, that is commonly found in soil. The disease is very damaging to bentgrasses (Agrostis species). Most turf initially contains a fairly low percentage of bentgrass (usually browntop bent, Agrostis tenuis), but the proportions of the different grass species can change with time. Expect to see damage from mid-summer until autumn.
The same fungus is a serious root and foot rot of cereal crops.
These symptoms are seen most often in summer, especially if the lawn comes under drought stress.
You may see the following symptoms:
- Patches or rings of affected grass with reddish leaves turning brown as the grass is killed
- Patches can vary in size from 1–2cm (½–1in) to 1m (3¼ft) or more in diameter. The centre of the patch often becomes colonised by grasses with more resistance to the disease, such annual meadow grass (Poa annua), or by broadleaved weeds
- The roots of the grasses blacken and decay, and it is often easy to peel back the affected turf due to the lack of roots
Take-all patch can be difficult to eradicate once it has developed. Over time, there may be a build-up within the soil of micro-organisms antagonistic to the take-all fungus, resulting in lower disease levels (a phenomenon known as ‘take-all decline’). In practice, however, it may be better (and certainly quicker) to over-seed affected areas with ryegrass or fescues.
Scarifying the turf with a lawn rake or electric scarifier in autumn will remove thatch and moss and increase aeration. Poor drainage and compacted areas can be alleviated by forking or by the use of a solid-tine or hollow-tine aerator. Ensure that the lawn is growing strongly by applying adequate (but not excessive) fertiliser. The pH of alkaline soils can be reduced by using acidifying fertilisers such as ammonium sulphate.
There are no fungicides available to home gardeners for the control of take-all. Some lawn maintenance companies offer treatment with a professional fungicide, but there is strict legislation controlling the application of professional products to domestic gardens. You will therefore need to satisfy yourself that the company is operating within the law.
The development of take-all patch is favoured by alkaline soil conditions. A soil may be naturally alkaline, but the pH can also be increased by liming, top dressing with a material with high lime content or even by irrigating with hard (alkaline) water.
Poor drainage can lead to rapid spread of the disease, but soils with a high sand content are also very prone to attack. Excessive thatch can also lead to problems by increasing moisture levels.