Fusarium Turf Fungus (Microdochium Nivale)
What is Fusarium?
This is a common turf disease, which attacks the turf when local conditions are conducive for the organism to become active. This commonly attacks the poa annua ( annual meadowgrass ) as this is a very high dominate species of most grass swards.
Mycelium will start appearing on the infected area. This is white in colour and most easily described as ( foamy looking ) As the disease gathers momentum the colours start to change. After the Mycelium has gone the leaf will start to brown off . If the disease continues the patches will increase in size and look more aggressive with a dark black ring appearing around the outside. And eventually leaving bald patches on the turf.
Cultural practices will help i.e aeration sand etc . Applying Iron will also help to keep leaf dry and reduce risks . Also remove dew off the grass plant to help keep leaf as dry as possible. Ideally you will be treating this before all these stages start, as the further through the cycle the disease is, the harder it becomes treat.