Fusarium Patch Disease (Microdochium nivale)

This is arguably one of the most common and damaging of the cool season diseases. Although it can occur at any time of the year it is more common during the cooler autumn and winter months in the UK.

Fusarium patch is more troublesome on closely mown turf such as golf & bowling greens. Although most types of grass species are susceptible, annual meadow grass (Poa annua) dominated swards are very prone to attack.

Identifying Fusarium Patch

The first signs of infection are small 10 - 20mm water soaked orange - brown patches. In the right conditions these patches will rapidly increase in size up to 300mm in diameter. 

As the severity increases the patches can join together causing extensive damage. Sometimes (early morning when there is a heavy dew) white cobweb like structures can be seen on the infected area. These white structures are known as mycelium.

If the disease is not controlled then the whole plant may die, leaving unsightly scars in the turf that will not properly recover until spring time with the onset of growth.

Favourable conditions for Fusarium Patch

• Cool and damp soil conditions typically associated with the autumn and winter periods.
• Excess levels of nitrogen caused by applying high nitrogen feed during the late summer early autumn period will increase the risk of a disease outbreak.
• An sheltered or shaded areas that lack air movement and sunlight will be more prone to attack.
• Areas of turf that contain a high percentage of Annual meadow grass (Poa Annua) will be very susceptible to Fusarium Patch.
• Surface alkalinity (high pH) caused by applying materials such as lime will increase the risk of Fusarium.
• A wet rootzone caused by poor drainage or an excessive thatch layer will only encourage dampness in the base of the sward, thus increasing an outbreak.

Preventing and controlling Fusarium Patch

• Avoid applying applications of fertilizer with high nitrogen inputs late in the growing season. Apply a fertilizer with high levels of phosphate and potash. These nutrients (especially potash) are essential for good winter turf hardness and will help against disease.
• Routine mechanical operations such as scarifying and aeration will help control the thatch layer, relieve soil compaction and encourage a dry surface.
• Removing early morning dews to help promote a dry surface will help reduce the risk of a disease outbreak. Removing or pruning back any tree branches or vegetation will encourage airflow and increase available sunlight to help keep the turf drier.
• If possible reduce the percentage of annual meadow grass in the sward by encouraging grass species such as bent and fescue with good turf management techniques.
• Fungicides are available to turf professionals such as golf greenkeepers for the control of Fusarium patch.