Our LocationsMine Lease, Planning and ApprovalsThe Mining and Rehabilitation ProcessEnvironmental ManagementCommunityOur PeopleHistoryNews and Events
What is Dieback Disease?
 
Dieback is the common name used for the plant disease caused by the organism Phytophthora cinnamomi (Pc). It was often referred to as jarrah dieback because jarrah is the most obvious species affected by the disease, however scientists now estimate over 2000 native plant species in Western Australia could be susceptible to Pc. Sites at risk include banksia woodlands, coastal heaths and the Stirling Ranges, so today the disease is more properly referred to as Phytophthora dieback.
 
Pc is believed to have been brought into Western Australia soon after European settlement. The symptoms of the disease were first seen in the 1920s, but the cause was not discovered until the mid 1960s.
 
Pc spores are spread through the soil and water, but not in the air.  The warm and moist conditions in spring and autumn provide ideal conditions for Pc to grow, multiply and spread.  Pc feeds on living plant roots and stems to get the nutrients it needs.  The vertical roots of a plant are invaded by Pc and they can no longer transport water to the leaves and the tree dies.
 
The disease is widespread and many species of plants in the jarrah forest are killed when their root systems are infected by Pc.  However, in the southwest of WA there are still large areas that are disease free. The major risk of transferring Pc is through movement of soils between disease free and infested areas. This may occur during various human activities which include four-wheel driving, wood collecting, logging, road construction, mining and bush walking. Even small amounts of soil on the underside of vehicles can be enough to start a new outbreak of the disease.
 
Natural spread is about one metre per year uphill but downhill spread can be far greater as the spores can move in water running through the soil, or in water moving along the caprock just under the topsoil. But the main spread is still from human activity.  Currently, there is no known large scale or practical method to eradicate Pc once it is established in the forest.
 


Life cycle of Phytophthora cinnamomi.

Click image to enlarge.


Life cycle of Phytophthora cinnamomi.