Weeds & Diseases
Red thread disease
Red thread disease is a common disease of turf in the UK.
What does Red Thread look like?
Red thread disease forms irregularly shaped, pale pink areas of turf during the lawn’s growing season. The leaves of the grass often die and are matted together by fungal growth. Often there are pink fluffy fungal growths or coral red needle-like outgrowths, which give the disease its name of red thread.
How can I avoid Red Thread developing in my lawn?
The condition of the soil under the turf is very important in defending against disease attack; a well structured, free draining soil will help to produce healthy turf.
Using a pre-turfing fertiliser will help prevent its development on less fertile sites. Once the turf has rooted down and established, the lawn should be fed occasionally as recommended using a fertiliser with a high nitrogen content.
Can I control it chemically?
The only chemical fungicide control for red thread disease currently available is Bayer Lawn Disease Control ( a.i. triflloxystrobin), available from most garden centres. Please follow the instructions when applying this product.
However, it is usually not necessary to use a fungicide for the control of this disease, as it rarely kills the grass outright.
Fusarium patch disease
What does it look like?
Fusarium patch disease is the most common disease of turf in the UK.
Irregularly shaped orange-brown areas of turf of a few centimeters in diameter develop, sometimes with a white or pink fluffy fungal growth around the edge of the patch. Over a period of weeks these die back and can create areas of bare ground. These gradually recover naturally if weather and soil conditions are warm enough. However, if the disease occurs in the autumn, growing conditions may not be suitable for recovery until the following spring. The disease can occur throughout the year, but is most damaging in autumn/winter because the turf is not growing fast enough to recover quickly.
The symptoms can become worse if snow falls on infected turf. The layer of snow insulates the disease fungus from the cold and allows it to grow beneath the snow, when it becomes known as ‘snow mould’, and more extensive damage can occur.
In most cases, the diseased area will completely recover once the grass is actively growing again.
How can I avoid it developing in my lawn?
Avoid damp and shady locations with still stagnant air for laying turf. In order to keep the lawn surface dry, mow regularly to prevent the leaves of the grass becoming too long. Air movement dries the lawn surface, making conditions less suitable for growth of fungal diseases.
The condition of the soil under the turf is very important in defending against disease attack; a well-structured, free draining soil will help produce healthy turf.
Can I control Fusarium Patch disease chemically?
The only chemical fungicide control for fusarium patch disease currently available is Bayer Lawn Disease Control ( a.i. triflloxystrobin), available from most garden centres. Please follow the instructions when applying this product.
Toadstools in recently laid turf
Why do they grow in my lawn?
It is very common for small brown toadstools or mushrooms to appear in recently laid turf. When turf is being harvested, damage is caused to the roots and other underground parts of the turf. Microscopic bacteria and fungi which are present in all soils decompose this dead and dying tissue once the turf has been laid. This process of biological decomposition, which breaks down organic matter in the turf, occurs naturally throughout the garden.
For most of their life cycle the fungi that feed on the dead material in the turf are too small to easily see. However, under certain weather conditions the fungi move into a reproductive phase and produce the small brown toadstools found in the turf. The spores released from the toadstools fall to the ground or are carried long distances on the wind. The air is full of the microscopic spores of various fungi and they will only grow if they find suitable conditions. In the case of newly -laid turf, the spores only grow if a suitable food source remains in the turf. Once the dead material in the turf has gone, the toadstools will go as well. It is very unlikely they will return in quantity.
Are they poisonous?
Without accurate identification, it is impossible to say whether a particular toadstool is poisonous. As a precaution, it would be wise to keep small children away from them since they may be harmful if eaten in quantity, as is the case with many things found in gardens.
Can they be treated?
There are no fungicides recommended in the UK for use against these toadstools. However, since they are not damaging the turf, and are part of a natural and temporary process, there is no need to treat them.
If you are worried about children eating them in the garden, the best approach is to remove the toadstools from the lawn by mowing the affected area on a daily basis until no more are produced. Provided the lawn is not mown at less than 25mm height of cut this will not damage the turf. Alternatively, breaking their stems by brushing the toadstools will allow them to dry out and disappear- they are composed mainly of water.
Annual Meadow Grass (Poa Annua)
Annual meadow grass (also commonly known by its Latin name of Poa annua) is sometimes found in rolls of cultivated turf.
Annual meadow grass is one of the most widespread grasses in the world. It will grow in the cracks between paving stones and in roof gutters and is the dominant grass in most UK golf greens.
Most established lawns contain some annual meadow grass, but it usually blends in well with other grasses. It is s common weed of arable land and thus is often found in cultivated turf. Although it is called annual meadow grass, some forms of it are short-lived perennials and will therefore persist from year to year.
Annual meadow grass has no perennial underground stems or roots so if the shoots are completely removed it cannot re-grow.
Turfgrowers around the world do their best to control annual meadow grass in their production fields, and the TGA members take quality control very seriously. It is very difficult to selectively kill one grass species growing in a mixture with other types of grass. Until quite recently, it was possible for turfgrowers to use chemical control to eliminate annual meadow grass from turf. Unfortunately, however, the main herbicide that was used to do this is no longer available and cultural methods which are less reliable have to be used.
Before harvesting the turf the grower will assess the amount of annual meadow grass present, if it is deemed to be within acceptable limits the turf will be passed as fit for sale.
How to minimise it in the lawn
Annual meadow grass in a lawn can be made less noticeable by good management, it often has a pale green colour and applying a fertiliser will help improve its colour so that it blends in with the rest of the lawn.
Because the grass spreads by seed, it is best to remove grass clippings when mowing. As well as this brushing the turf to raise the seed heads prior to mowing will help to remove them. It should not be necessary to use a powered scarifier on a recently laid lawn but hand raking and brushing can help.
Mowing of the new lawn should commence as soon as the turf is well-anchored to the soil underneath. Lift a corner of the roll to see how well it has rooted and then begin mowing-aiming to get the mowing height of the turf back to what it was when it was delivered as soon as possible after laying. The turf should not be allowed to get very long, ideally, it should have no more than about a third of its length removed at each mowing.
Infrequent mowing can also have the effect of making the isolated annual meadow grass plants in a new lawn appear more widespread than they actually are, because the individual stems of the grass are able to radiate out sideways from their base.
To remove clumps of annual meadow grass in a relatively small area it is possible to weed it out by hand by cutting through the base of the plant just below the surface of the soil using a sharp knife. Any bare ground revealed should then be lightly scratched and a good quality seed mix to match the turf should be sown to repair the patch.
Alternatively, carefully treat each annual meadow grass plant in the lawn using Roundup Gel (from a garden centre), following which it will gradually turn yellow and die. Bear in mind that this is a total weed killer and will kill every plant it touches, so do it carefully.