Ganoderma australe, also known as the southern bracket, is a common wood-rotting fungus that is found in many regions of the world.
This species is particularly problematic in Tasmania, where it can cause significant damage to native trees, especially Acacia dealbata (silver wattle).
This fungus is a perennial bracket fungus, which means that it can live for several years. It causes white rot, which is a type of wood decay that breaks down all components of wood, including lignin and cellulose. This causes the wood to lose its structural strength, which can lead to the eventual collapse of the tree.
Ganoderma australe is believed to be parasitic during its early colonization, meaning that it forms a symbiotic relationship with the tree, taking its energy from a living host. This is similar to mycorrhizal fungi, but without any benefit to the host. Instead, the fungus can eventually cause the death of the host tree.
As the host tree dies, Ganoderma australe becomes saprobic, which means that it decomposes and breaks down dead organic matter to use as an energy source. The fruit bodies of this fungus usually appear on the lower stems of trees or at points of damage, such as limb failure or pruning wounds. While it is most commonly found on hardwood trees, it has also been found on pines.
One of the most significant impacts of Ganoderma australe is its effects on Acacia dealbata, commonly known as silver wattle (see figure 1). This tree is native to southeastern Australia, including Tasmania. It is an important component of many ecosystems and is valued for its timber and ornamental qualities. However, when infected with Ganoderma australe, the tree can become severely weakened, leading to eventual collapse and death.
In this article we will answer:
- How do I identify the Ganoderma australe?
- What is the current research surrounding Ganoderma australe?
- How can we help?
Figure 1. Ganoderma on a large acacia dealbata (Silver Wattle) located near Margate, Tasmania.
Figure 2. The underside of a fruiting body of Ganoderma australe.
How do I identify the Ganoderma australe?
Identification of Ganoderma australe is relatively straightforward. The fungus produces large, tough bracket fruit bodies that can grow up to 25cm across and 5cm to 25cm thick. The margin and lower surface of the fruit bodies are pale or white, while the upper surface is dark brown. The spores of the fungus are brown and are released in late summer and autumn, forming a dusty covering on the lower surface of the fruit body.
What is the current research surrounding Ganoderma australe?
Research on Ganoderma australe is ongoing, as scientists seek to understand the biology and ecology of this species, as well as its effects on trees and forests. Some studies have focused on the genetics of the fungus, as well as its interactions with other fungi and bacteria in the soil. Other research has looked at the impacts of the fungus on forest ecosystems, including changes in carbon cycling and nutrient cycling.
The brown spores of the fruiting body of Ganoderma australe
One study published in the journal Forest Pathology in 2019 looked at the distribution and host range of Ganoderma australe in Tasmania. The researchers found that the fungus was most commonly associated with silver wattle, but also occurred on other tree species, including eucalypts and blackwoods. The study also found that the distribution of the fungus was closely linked to the availability of suitable habitat, including areas with high rainfall and low soil pH.
Another study published in the journal Phytopathology in 2013 looked at the molecular biology of Ganoderma australe. The researchers sequenced the genome of the fungus and identified several genes that are involved in the degradation of lignin, a major component of wood. They also identified several genes that are involved in the formation of fruit bodies and the release of spores. This research provides important insights into the biology of the fungus and could lead to new strategies for managing its impacts on trees and forests.
How can we help?
Tasmanian Tree Care and it’s highly trained arborists can identify potentially harmful fungi in your garden or property. If you’re unsure about the health of your natural assets, please contact us to organise an assessment.
Figure 3 courtesy of Paul George (iNaturalist Australia), https://www.inaturalist.org/photos/60418205
Content collected by Jack Colbeck
Jack Colbeck is an understated high achiever with skills, humility and humour in equal measure. Jack is responsible for quality control and delivering professional tree services to our valued clients. Jack is passionate about growing and planting trees to offset the negative impact of removing trees.
Ganoderma australe FACT SHEET
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