Turf diseases are usually caused by fungi invading plant tissues and robbing them of essential nutrients. Alternatively, they can be caused by fungi inhabiting the plants root zone and starving the plant of water and nutrients. However caused, turf diseases need to be dealt with in order to restore your lawn to full health.
There are many diseases which attack turf. Fortunately most of these diseases are found mainly in intensively managed turf where fine grass species have been used. Domestic lawns are usually created using Perennial Ryegrasses, this is because they have excellent resistance to wear and are tolerant of the climate in the UK. The main turf disease threats to domestic lawns are:
Lawn Rust Disease
Rust is a common foliar disease of turf. It is caused by various fungi, usually Puccinia or Uromyces species. Infected areas may produce huge numbers of air-borne spores.
Typical symptoms of lawn rust include;
Affected patches of grass turn yellow
Large numbers of tiny, spore-producing pustules break through the leaf surface. The colour of the pustule will depend on the species of rust and the type of spore it is producing. Most commonly the pustules are orange, but in autumn the fungus may switch to producing black pustules containing over-wintering spores
When walking over an affected lawn, shoes or clothes turn orange as they become coated with vast numbers of spores
Severely affected leaves may turn brown and shrivel, but the rust does not usually kill the grass
Feed the lawn regularly during the growing season to maintain vigour
Avoid high nitrogen fertilisers in the autumn, as the resultant lush growth may be more prone to attack by rust and other diseases such as Fusarium patch
Mow regularly to reduce the number of affected leaves, removing the clippings
Improve air circulation by selective pruning of overhanging trees and shrubs
There are no fungicides available to gardeners for the control of rust on lawns. Chemical control of rust is usually unnecessary, however, as the symptoms are temporary. Even lawns that are heavily infected in autumn will usually produce healthy growth by early summer of the following year.
Red thread is a common cause of patches of dead grass on lawns during wet summers and in autumn. It is caused by the fungus Laetisaria fuciformis. Red thread will rarely kill the grass completely, and the patches will recover with appropriate remedial action. The disease can develop at any time of year, but is most common in late summer and autumn.
It is most serious on red fescue (Festuca rubra), but other fescues, bents (Agrostis spp.), perennial ryegrass (Lolium perenne) and annual meadow grass (Poa annua) are also attacked.
You may see the following symptoms:
Patches of affected grass with a reddish tinge at first, later becoming light brown or almost bleached in appearance
Patches vary in size from 7.5cm (3in) to 25cm (10in) in diameter but can be much larger
Two types of fungal growth may be seen on the patches, particularly under wet or humid conditions. Both are visible to the naked eye, but are seen better with a hand lens or magnifying glass.
The first takes the form of small, pink, cottony flocks, and can be confused with growth of the fungus causing snow mould
The second is specific to red thread, and gives the disease its common name. Pinkish-red, gelatinous, thread-like structures (stromata), 1-2mm (less than ¼in) in length, are produced on the leaves and may bind them together
If red thread appears, application of nitrogen to the affected area will often be sufficient to control it.
The threat from red thread can be reduced by taking action to improve the drainage and aeration of the turf. Scarifying the turf will remove thatch and moss and increase aeration. Poor drainage and compacted areas can be alleviated aerating Ensure that the soil is not deficient in nitrogen. Disposing of (not composting) grass cuttings will reduce the amount of fungus present to re-infect the lawn.
This disease is caused by the fungus Microdochium nivale. It is one of the most damaging diseases of turf grasses and can be difficult to control. It is found most frequently during autumn, winter and early spring, but attacks can occur at any time of the year.
The disease is sometimes very noticeable after thaws of snow, when it is given the common name of snow mould.
Fusarium patch is particularly troublesome on annual meadow grass (Poa annua), but can also affect bents (Agrostis species), fescues (Festuca species) and perennial rye-grass (Lolium perenne).
What to look out for;
The disease is first noticed as small patches of yellowish, dying grass that later turn brown
Patches increase in size and may reach 30cm (12in) or more in diameter, often merging together so that large areas can be affected
During wet conditions a white or pinkish, cottony fungal growth may be noticed, particularly at the margins of the patch. This is not to be confused with another fungal disease called red thread, or with slime moulds in turf
Ensure that the lawn dries rapidly after dews or rainfall by improving the aeration and drainage. This can be done by a combination of scarifying, spiking and hollow- or solid tining
Improve general airflow over the lawn by pruning back overhanging trees or shrubs
Remove heavy dews in the morning with a switch or bamboo cane
The Sports Turf Research Institute recommends using iron sulphate, a mosskiller, to reduce the severity of the disease. This compound toughens the grass and has an acidifying effect on the turf, which in turn discourages snow mould.
Dry patch is just one of the many factors that can cause the appearance of dead patches in lawns. Other possibilities include insect pests, fungal diseases, spilt mower fuel, and dog or fox urine.
Dry soil due to prolonged hot, dry weather will also cause the grass to turn brown, but in this case there is usually good recovery once rain returns. However, with dry patch there is no recovery after rain as the water cannot penetrate the soil to reach the roots.
The causes of dry patch are complex and poorly understood, but a common cause is thought to be the coating of soil particles with water-repellent chemicals due to the growth of fungi.
You may see the following symptoms:
Patches or irregular areas of the lawn turn first a darker green colour, and then brown
The symptoms may develop during dry weather, but the problem does not improve with the return of rain or by watering the patches
The soil underneath the affected patches will be found to be completely dry. Any water applied will simply run off or sit on the surface of the soil
In extreme cases puddles may form on the surface following rainfall, as if the area is waterlogged, but the soil will still be bone-dry beneath
Occasionally there may be an obvious white growth of fungal mycelium visible, or a fungus-like smell to the thatch or soil
To help prevent dry patch:
Scarify the lawn in autumn to remove accumulations of thatch
Avoid soil compaction, and improve water and air penetration to the roots by aerating the lawn.
Feed at the appropriate times to promote strong, healthy growth with a vigorous root system
If dry patch develops it can be very difficult to re-wet the soil, but the following may help:
Spike the area densely, and attempt to apply some water each day for a few days (don’t overwater as it will just run off)
Consider applying a wetting agent (see chemical control, below)
Repeat the treatment once a month for 3-4 months
In severe cases that do not respond to treatment, the affected turf plus three or four inches of soil may need to be removed, and the soil replaced before re-seeding or re-laying with fresh turf
Wetting agents are often used by sports turf professionals to treat dry patch. These are chemicals that aid the absorption of water by soil particles. Repeat treatment is likely to be necessary, in conjunction with the cultural methods outlined above.
An effective pest and disease control program firstly requires identification of the disease or the undesirable species and secondly the problem needs to be brought under control and eliminated. To control pests and disease turf Stripes Lawn Care use market leading products that will quickly and effectively deal with unwelcome turf pests and diseases.