Fusarium patch disease is the most common disease of turf in the UK.
The Latin name of the fungus that causes the disease symptoms is Microdochium nivale but in the past its Latin name was Fusarium nivale, hence its common name.
What does Fusarium look like?
Irregularly shaped orange-brown areas of turf 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, the 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 mold, and more extensive damage can occur.
In most cases, the diseased area will completely recover once the grass is actively growing again.
Why has it affected my turf?
As with all plant diseases, the spores of this disease are abundant everywhere, but only produce symptoms if environmental conditions are right for their growth.
When is Fusarium likely to appear?
Whenever the weather is very still and humid and the grass stays wet for most of the day, Fusarium patches are likely to develop.
Fusarium is rarely a problem in the summer but is very common at other times of year under these weather conditions. The fungus grows in the water film on the grass leaf and that is why heavy dews and still air favour its spread.
How can I avoid it developing in my lawn?
Avoid over-feeding. Avoid damp, 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 chemically?
There are currently no fungicides recommended for use by amateur gardeners in the UK to control this disease.
Should I contact the turf grower about the disease on my turf?
Only if the symptoms were present on delivery or develop within a couple of days afterwards.
Lay turf in sites where air can flow over the surface of the lawn to dry it out. Do not feed any more than necessary - many lawns do not need feeding if laid on fertile soil.