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Thursday, 22 January  2009  Plant Disease

Find out about a disease that is attacking plants in Western Australia.

DIANNE BAIN: It's known as WA's wildflower wonderland - Bluff Knoll - the highest peak in the south west and now home to what's been described as the AIDS of the plant world - Phytophthora dieback.

DR COATES: Basically it infects the roots and then it ultimately destroys the root system and the plants die from lack of water and nutrients.

DIANNE BAIN: Dr David Coates has studied dieback for more than 20 years.

DR COATES: It's amazing when you think that such a simple little organism can do so much damage.

DIANNE BAIN: He's seen WA's rare and endangered plants consumed by the fungus, but perhaps his most alarming discovery was on Bluff Knoll.

The disease has since been discovered in other areas of the State. It's even in the Kalamunda hills and metropolitan backyards.

Whilst preventative measures have limited its spread, it hasn't stopped it, and over the years dieback has continued to quietly march on. It's a worrying trend that now has scientists comparing the disease to salinity.

Dieback was first identified in WA during the 1960s, and a decade later it had caused so much destruction the Government took the dramatic steps of quarantining large chunks of state forest to try and stop it spreading.

DR COATES: Basically, the objective is to prevent movement of soil which is carrying the disease into uninfected areas.

DIANNE BAIN: A few years on, and scientists had a breakthrough - Phosphite. The chemical is injected or sprayed on the tree, but it's no miracle cure and it will only extend the life of a tree or plant by about three to five years.

And it's not just the bush that's affected. Dieback has now made its way into back gardens and many people don't even know it's there.

The garden plants most susceptible to dieback are banksias. Once infected, it only takes about three weeks for the plant to die. There's grevilleas, macadamias and avocados. One of the most critically endangered species on the dieback hit list is the lambertia. CALM now houses the world's largest collection of lambertias in a glasshouse in Bentley.

It's hoping to one day replant these seedlings when dieback is completely eradicated. The question is: will that day ever arrive?

DR COATES: It's very hard to make predictions about how far this disease is going to go.

DIANNE BAIN: What's clear is that preventative measures alone are not good enough.

DR COATES: We're already seeing devastating effects of it and I guess the longer we go, the worse it's going to get.

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English Bites - Plant Disease
story notes

To infect means to invade and produce disease in.

Nutrients are any substances living things need to live and grow.

 rare and endangered
Rare means uncommon. Endangered means in danger of extinction.

Alarming means causing fear.

 preventative measures
Preventative measures are plans to stop something before it happens.

The objective is the aim - the goal you plan to achieve.

Uninfected means not infected - soil that doesn’t have any of the fungus in it.

Take a look at the parts of a plant.

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