Sudden oak death

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​​​​​ Leaf blight and shoot dieback on rhododendron caused by sudden oak death.


Sudden oak death

Exotic to Australia

Leaf blight and shoot dieback on rhododendron caused
by sudden oak death. Credit: Sabine Werres BBA, Braunschweig,
Germany, PaDIL

Features: A disease caused by airborne species of the
fungus-like organism Phytophthora that spreads easily and kills
even mature trees

Where it’s from: North America, Vietnam, South America,
New Zealand, Japan and Europe

How it spreads: Importation of spores on infected plants and
plant material, compost, clothes, equipment and animals

At risk: Forest species, avocado, ornamentals, chestnut, hazelnut,
macadamia, blueberry, and production nurseries;
native species and forestry

Report it


Keep it out

Sudden oak death, caused by a fungus-like organism Phytophthora ramorum, causes serious and widespread damage in nurseries and natural woodland throughout Europe and North America. It affects over 130 tree and shrub species and overseas it is killing trees in the millions, even mature trees. Derived from Greek, the word phytophthora means ‘plant destroyer’.

Sudden oak death causes symptoms on stems, trunks and leaves. It produces airborne spores which means it can spread quickly in new environments.

Another airborne phytophthora species, P. kernoviae also causes significant damage to a wide number of plant types.

Sudden oak death threatens Australia’s tree crops including avocado and nuts, as well as nurseries. It also poses a significant risk to Australia’s natural environment since eucalypts and other key native species can be infected.

Importing goods

To keep sudden oak death out of Australia, never ignore Australia’s strict biosecurity rules.

Import shipments may need to be treated and certified, so before you import, check our Biosecurity Import Conditions system (BICON).

What to look for

Sudden oak death causes two distinct sets of symptoms, depending on the host species.

On trees:

  • trunk cankers—brown or black discoloured outer bark
  • ‘bleeding’ sap.

On crops and shrubs:

  • leaf blight— dark brown spots or blotches spreading across the leaf, which may drop
  • shoots become blackened with or without foliage attached.

The age of the plant, the host species and time of the year can all affect the severity of the symptoms. Wet, cooler periods of the year support the growth of the disease.

Leaf damage caused by sudden oak death. Sabine Werres BBA, Braunschweig, Germany, PaDIL.
Trees appear to bleed as resin oozes from cankers on stems and trunks. Joseph O’Brien, USDA, PaDIL.











Where to look


Sudden oak death would most likely arrive in Australia on infected plants or plant material. It could also invade as spores in soil or on dirty shoes, clothes and personal items.

Nursery owners, growers and home gardeners

Look for leaf damage, die back and stem cankers on shrubs and trees including:  

  • avocado
  • plantation forest
  • macadamia
  • tea tree
  • chestnut
  • hazelnut
  • blueberry
  • ornamentals including camellia and rhododendron
  • production nurseries
  • Australian native plants.

What to do

If you think you’ve found sudden oak death:

  • don’t move samples
  • take a photo
  • do not disturb the pest (this may be a simple as closing the doors on a shipping container or preventing access to an orchard)
  • wash your clothes and boots.

Read the detail

Last reviewed: 21 May 2021
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