Phytophthora

Phyton = ‘plant’, phthora = ‘destruction’. ‘The plant destroyer’

 

Phytophthora is a water-borne plant pathogen that is causing untold destruction to Australian ecosystems. The fungus-like pathogen can remain dormant in the soil for long periods during dry conditions and once present, is virtually impossible to eradicate.

 

Grass Trees are particularly vulnerable to Phytophthora and often used as indicators (Credit: RBG Sydney)

Phytophthora grows in the soil in a hyphae-like fashion, just like a fungus and it rots the roots of susceptible plants which in turn are unable to take up water and nutrients from under the ground and so they die. The result is often called phytophthora dieback. This can happen in a forest or woodland, market garden or even a home garden. Woody heathland with a predominance of Proteaceae species is particularly vulnerable.

 

Worldwide there are probably several hundred species of Phytophthora. By all accounts, the Great Irish Famine of 1845-49 caused by the potato blight was a Phytophthora event. About 1 million people died of starvation and disease and many more emigrated to Europe and America or sought refuge in England.

 

The Friends of Mt Cannibal (LINK), recently conducted a phytophthora workshop at Mt Cannibal, led by Dr Mary Cole from Agricultural Pathology and Biological Farming Service (LINK).

 

Dr Cole gave a background to Phytophthora including how it spreads, how to take soil samples for testing and how to mitigate the spread – ‘arrive clean and leave clean’.

 

Basically, any activity that involves the movement of water, soil or plant material can spread the pathogen. Even ‘elementary’ activities such as bushwalking and home gardening can result in Phytophthora being spread throughout a specific location and even from region to region.

 

Activities that involve large scale movement of soil or plant material – mining, forestry, road building, housing developments, etc – are of particular concern.

 

Dr Cole demonstrated how to clean footwear and tools before taking soil samples and how to dispose of potentially contaminated materials. It is vital that these procedures are conducted diligently when moving between sites on the reserve.

 

The Friends of Mt Cannibal now have a basic Phytophthora background and will soon commence a sampling program based on likely geographic zones in the reserve that might be at risk of infection. The friends-group will also attempt to devise an education and mitigation strategy to help protect the incredible biodiversity of the reserve.

 

Most of the plant species within the Mt Cannibal Flora and Fauna Reserve have adapted over millennia to cope with bushfire as evident at present by the restorative undergrowth and epicormic sprouting on trunks and branches. The question is, could they withstand an insidious invasion of Phytophthora, the ‘plant destroyer’?

 

Further reading:

Dept of Agriculture Water and Environment Threat Abatement Plan for Phytophthora LINK

Dept of Sustainability and Energy (DELWP), Phytophthora Management Strategy LINK

Parks Victoria Weeds and Diseases LINK

Royal Botanic Gardens Sydney, Facts About Phytophthora brochure LINK