Phytophthora cinnamomi (Cinnamon Fungus) and Bush Dieback

Biology and ecology

Topic index

What phytophthora is and how it impacts on the bush
Susceptible species and ecosystems
How phytophthora spreads
How damaging is it?

1. What phytophthora is and how it impacts on the bush

Phytophthora (otherwise known as bush dieback) is an introduced, soil borne fungus that infects and kills plants. Both native and introduce species are susceptible. It is thought to be a native of South-East Asia, but is now impacting on ecosystems and agriculture World-wide.

It is one of the most important threats to the integrity and character of native ecosystems, flora and fauna in Australia. The disease kills a wide range of undergrowth species, thereby dramatically reducing floristic diversity, changing vegetation structure, degrading habitats required by native fauna, and by consequence reducing or eliminating populations of fauna species such as many birds and small mammals including pygmy possums, native rats and mice, bandicoots, dunarts, antechinus etc. In addition, as undergrowth diversity and density is reduced, bushland becomes more susceptible to invasion by weeds and by feral animals.

For detailed information on phytophthora, visit the Dieback Working Group website.

A list of other informative websites is presented on the links page.

2. Susceptible species and ecosystems

Species in many flora families are affected, including the Proteaceae, Myrtaceae, Epacridaceae (heaths), Xanthoreaceae (grass trees) and Fabaceae (peas).

Genera in Myrtaceae family with susceptable species include Baeckea, Beaufortia, Darwinia, Leptospermum, Melaleuca, Thryptomene and Verticordia.

Susceptable Eucalyptus species in the Otways include Eucalyptus regnans (Mountain Ash), E. radiata (Narrow-leaved Peppermint), E. oblique (Messmate), and E. baxteri (Brown Stringybark).

Genera in the Proteaceae family with susceptable species include the Banksia, Waratah, Grevillea, Hakea, Isopogon and Lambertia.

Genera in Epacridaceae family with susceptable species include the Andersonia, Astroloma, Brachyloma, Epacris, Conostephium, Leucopogon, Monotoca, Stypheli and Spengellia.

Species of the Proteaceae and Epacridaceae are particularly prevalent in heathlands and heathy woodlands, which are commonly found on sandy, waterlogged or otherwise infertile soils in temperate Australian regions, such as the Otways. In the Otways, such vegetation is most common on the sandy flanks of the ranges, such as around Angelsea, Forrest and Gellibrand. In the northern Otways between Deans Marsh, Forrest and Gellibrand this geological formation is known as the Yaugher Sands.

Phytophora cinnamomi also impacts on non-native species, including many that are horticulturally and economically important. Impacted species include oaks, myrtles, many stone-fruits, lupins, nuts, vegetables, lilies, camelias, hibiscuses, rhododendrons and some species of conifer.

Non-native forestry species are also impacted, most notably Pinus radiata.

3. How phytophthora spreads

Phytophora is spreading in the Otway ranges and other natural areas in Victoria and Australia. Once a site is infected the fungus creeps through the soil. The rate of progress on flat terrains may be just a few tens of centimetres per year, but it can spread down slopes by many metres per year. Along drainage lines, dispersal can be very rapid.

Spread from site to site is aided by vectors such as vehicles, machinery, walkers, mountain bikes and horses. It has been reported that in Western Australia it has been spread into bush remnants by land-carers via infected tube-stock during revegetation projects.

4. How damageing is it?

Devastating! In affected areas the vegetation structure and species composition is changed dramatically, and many fauna species are no longer able to survive. In Western Australia large areas of national park have been severely degraded. In Victoria the Brisbane Ranges national park has been heavily hit.

Heathlands and heathy woodlands are converted to depauporate grasslands and grassy woodlands. (Natural grasslands and grassy woodlands include a diverse assemblages of species that are lost in depauporate phytophora induced communities).

Some species are able to germinate and re-establish, but for the most part they are lost and the entire ecosystem is irrevocably degraded.

For more details, see the websites listed at the bottom of this page.