Cinnamon fungus (Phytophthora cinnamomi) (Dieback)

An easily spread soil/water borne disease that causes dieback in plants, can easily be spread from one infected area to another through muddy vehicles and boots, digging implements etc.
http://en.wikipedia.org/wiki/Phytophthora_cinnamomi

Grass trees are particularly susceptible, but so too are
most understorey in drier forests. The spores survive in soil and spread through water, so mud is a perfect way for them to travel.


Photo showing dying grass trees alongside track in Brisbane Ranges.

Originally spread mostly through management vehicles, forestry and plant equipment, but now Parks Vic and DSE have better controls for their vehicles, and usually have mobile cleaning stations when doing works at infected areas.
The general public, especially those that love and care for the bush should know, as 4x4's, trailbikes, mountainbikes and bushwalkers all can easily spread the disease.


Photo showing dieback in centre. Stirling Range, Western Australia.