Fusarium patch disease is a fungal disease caused by the fungus Microdochium nivale. Fusarium can occur at any time of year, but it is more common during the autumn period, and if left untreated, throughout the winter months as well.

Fusarium disease is usually a result of damp and unfavourable conditions in your lawn which can be caused by all manner of issues, including excess shade caused by bracken or thatch build up, poor drainage caused by lawn compaction, or heavy rainfall.