Silent threat in the soil
Beneath the healthy appearance of the Australian bush lies a serious and often invisible threat: Phytophthora cinnamomi. Commonly referred to as Cinnamon fungus (though not scientifically accurate), it is also known as dieback, root rot, or jarrah dieback.
Phytophthora cinnamomi is not a true fungus but a soil-borne water mould. Despite its microscopic size, it is responsible for the decline and death of more than 900 native plant species across Australia. Its effects are slow and often unnoticed at first, gradually attacking plant root systems and preventing them from absorbing water and nutrients. By the time symptoms appear above ground, the damage is usually irreversible.
Plants from the heath, pea flower, banksia, and grass tree families are particularly vulnerable. As these plants decline, entire ecosystems are affected. Animals such as honeyeaters and honey possums lose critical food sources, and once-diverse landscapes can be reduced to sparse, degraded environments.
Why Phytophthora cinnamomi is such a serious threat
Phytophthora cinnamomi thrives in warm, moist conditions, which makes many parts of southern Australia especially vulnerable. The most concerning aspect of dieback is that it can remain hidden in the soil for years. During that time, it continues to spread, often unnoticed, until large areas of vegetation begin to fail.
Unlike storm damage or fire scars, dieback does not recover naturally. Once established, it permanently alters the composition of plant communities. In some cases, entire species disappear from affected areas.
Because the pathogen is invisible to the eye and symptoms can take years to appear, people may unknowingly walk through infected areas and carry contaminated soil into healthy environments.
How Phytophthora cinnamomi spreads
The primary way Phytophthora cinnamomi spreads is through the movement of soil and water. Human activity plays a major role in this process.
It can be transported by:
- Mud on boots, shoes, and gaiters
- Hiking poles and camping equipment
- Vehicle tyres and undercarriages
- Machinery and trail maintenance equipment
- Infected plant material
Wet and muddy conditions dramatically increase the risk of spread. When soil sticks to footwear or gear, the pathogen can be carried far beyond the original affected area.
What hikers can do to help stop the spread
Preventing the spread of Phytophthora cinnamomi is largely about awareness and simple hygiene practices. Small actions taken by individuals can make a significant difference.
- Clean your boots thoroughly: Before leaving areas known or suspected to contain dieback, remove all soil from your footwear. Pay close attention to tread, seams, and laces. Soil that looks harmless can carry the pathogen into healthy bushland.
- Stay on formed tracks: Stick to designated trails, especially during wet weather. Walking off-track increases the risk of moving contaminated soil and can damage fragile environments already under stress.
- Clean all gear that contacts soil: Boots are not the only concern. Hiking poles, tent pegs, camping equipment, and even backpacks should be cleaned if they come into contact with soil. Where cleaning stations are provided, use them.
- Know where dieback occurs: Familiarise yourself with dieback-affected areas and any local regulations before you visit. Park websites, signage, and rangers provide up-to-date information and guidance.
Why closed tracks and cleaning stations matter
Track closures, quarantined areas, and boot-cleaning stations are not arbitrary restrictions. They are essential tools used by land managers to protect vulnerable ecosystems and prevent further spread of dieback.
Ignoring closures or bypassing barriers can undo years of rehabilitation work and place entire ecosystems at risk. Even experienced hikers can unknowingly contribute to the problem by assuming closures “don’t apply” to them.
If a track is closed, it is closed for a reason. Respecting these measures protects not only the environment but also the long-term access to these places for everyone.
Additional ways to reduce risk
- Follow Leave No Trace principles and avoid moving soil or plant material between locations
- Avoid walking through muddy areas where possible
- If conditions are very wet, consider postponing your walk
- Ask local rangers about current conditions and alternative routes
- Avoid driving or riding off-road in areas known to contain dieback
It’s also important to remember that footwear is not the only vector. Vehicles, machinery, and contaminated plant material can all spread Phytophthora cinnamomi if hygiene practices are not followed.
A simple takeaway
Phytophthora cinnamomi spreads quietly, without warning, and its impacts are permanent. Once established, it cannot be removed.
The good news is that its spread is largely preventable. By cleaning boots and gear, respecting track closures, and staying informed, hikers can play a vital role in protecting Australia’s native landscapes.
Every step matters. The future health of the bush depends on the choices we make today.
