Fusarium Patch Disease [Microdochium nivale]

Lawn Care - Fusarium Patch
Fusarium patch disease is caused by the fungus Microdochium nivale (formerly Fusarium nivale). Fusarium is the most common and one of the most damaging diseases found on UK lawns and turf areas. It is becoming more of a problem as the winters become wetter and milder which favour this disease. We are also having fewer hard frosts in the UK, which kill of any pathogens that cause fusarium.
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Identification of Fusarium Patch

Fusarium patch usually appears in orange/brown circular spots up to 50mm or 2" in diameter. These spots will quickly increase in size under favourable conditions for the disease. They are quite noticeable during periods of early morning dew. During prolonged periods of moist weather a pink ring of mycelium can seen around the infected area of lawn or turf.

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Conditions that favour Fusarium Patch

There are many factors that favour an attack of fusarium patch disease. These factors are.

  • Mild and wet conditions.

  • A high percentage of annual meadow grass, which is very susceptible to fusarium patch disease.

  • High levels of fertility. Do not apply a high rate of nitrogen during late summer or early autumn as this favours fusarium patch.

  • A deep thatch layer.

  • A sheltered location devoid of sunlight.

  • Poor surface drainage.

  • A high surface pH.
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Prevention and control of Fusarium Patch

In the case of Fusarium patch prevention is better than cure. Once you have an outbreak it is very difficult to control without the use of fungicides, which are not available to the amateur gardener. However there are different cultural operations that will help with the prevention of this disease. These include:

  • Maintaining the correct nutrient levels - Don't apply heavy doses of nitrogen too late in the season as this encourages fusarium patch disease. Applying an application of potash in the early autumn will help harden the plant against the disease.

  • Remove dews in the morning, this can be done with a wide drag brush or a switch. A switch is a long cane or fibre glass pole that is swept across the lawn from side to side to remove the dew.

  • Change the grass type - annual meadow grass is very susceptible to fusarium patch. With the correct maintenance practices you will encourage disease resistant grasses.

  • Reduce the thatch layer if it is too deep by aeration and scarification.

  • Apply sulphate of iron - This will help acidify the surface of the lawn which will help discourage the disease. Avoid the use of lime unless absolutely necessary.

  • Improve the surface drainage with aeration and a sand based top dressing.

  • Improve any sheltered areas if possible by cutting back or pruning any vegetation which is causing a problem.