Disease and drought threat to iconic WA trees

October 17, 2011

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Researchers at Murdoch University are warning that thousands of beautiful Marri trees throughout the South West, including the wineries region, are dying or are already dead from a devastating form of tree cancer, known as Marri canker.

Professor Giles Hardy and Dr George Matusick from the Centre of Excellence for Climate Change Woodland and Forest Health have also identified that large areas of the Northern Jarrah forest from the Perth Hills to Collie have suddenly collapsed and died from drought. Wandoo, Tuart and WA Peppermint have also shown severe recent declines, with some of the dead trees estimated to be at least 150 to 200 years old.

They will reveal more about the extent of the tree crises, the causes and proposals to reduce and manage the declines at the Managing for Healthy Forests Symposium on Friday, October 21, in Henley Brook.

The Marri canker epidemic is severely impacting more than 80 per cent of all Marri trees along Caves Road, the Bussell Highway and the adjoining roads in an area heavily reliant on tourism.

“Marri is an iconic tree species in Western Australia but this cancer is destroying them and therefore the character and beauty of our famous Margaret River wine region is suffering,” said Professor Hardy, director of the Murdoch University-based centre.

“Currently the Marri canker is not completely understood and there are no known solutions. We are running out of time to find them.

“The deaths are impacting on flora and fauna biodiversity in the region. For example, the Carnaby’s Black Cockatoo rely on the Marri’s large fruit, known as honky nuts, for food.

“Collapsing trees with falling branches pose a significant hazard for pedestrians and drivers. It is very costly to remove these dead trees and repair the damage they do to fences and powerlines. But the cost to the tourism industry in the region could be even more devastating.”

Professor Hardy and Dr Matusick hope to obtain funds from the Australian Research Council (ARC) to research the cancer and other threatened trees.

Throughout this year, they have also been surveying large areas of the Northern Jarrah forest from the ground and the air to find that 17,000 hectares of eco-system have suddenly collapsed. As we move into summer, other endangered areas could also succumb, they warn.

“The collapse follows one of the hottest and driest summers on record and years of climate change,” said Dr Matusick. “All the climate change models point to an even drier and hotter climate for south west WA so it’s vitally important that we do something now to protect what is an iconic and vitally important habitat for native species of flora and fauna.

“These trees are the lungs of the south west. They provide us with our clean, fresh air, they provide habitat for our flora and fauna and Western Australians have a huge emotional tie to their native forests.

“We have modified these forests significantly since European settlement and they are no longer like they were prior to our arrival. In order to ensure these forests continue to provide these functions and services, we must look at new ways of managing them in a drying and warming climate.”

A number of scientists from Murdoch University, University of Western Australia, the Department of Environment and Conservation, the Water Corporation, University of Tasmania and the University of British Columbia will be at the symposium on Friday presenting on topics including recreationists’ perceptions of forest health and community involvement in trying to rehabilitate the Tuart Forest.

Event organiser Cielito Marbus said anyone with an interest in forest health and management should attend the symposium, which will be held at the Valley View Restaurant and Reception Centre in Henley Brook.

“It is clear that the action we take now will affect the health of our precious forests for many generations. So it is important that the scientific community, policy-makers and wider society exchange knowledge in an open forum,” she said.

“To plan for the future we have to understand better what is happening to our forests and that will take time, money and collaboration. Hopefully the symposium will be the catalyst for the start of many important partnerships.”

Delegates can register for the symposium on the dedicated website. Registration costs $100 per person with discounts for students and community groups.

Comments (7 responses)

Sandy Thomas(hort) Voyager Estate October 23, 2012

W.A. peppermints declining severely along creekline over last few years. comments? Dieback in appearance.

Giles Hardy October 23, 2012

Yes, WA peppermint is now showing signs of decline in many areas in the south-west of WA. This is especially so around the Busselton area. There is strong evidence that the trees are being predisposed to stress (e.g. from drying climate) and opportunistic pathogens getting into the canopy and killing branches from the top down. The pathogen is Neofusicoccum australe. However, we are frequently finding Phytophthora multivora in association with peppermint showing dieback symptoms. This pathogen is a fine feeder root pathogen and good well be assisting in the decline process. But more work is required on peppermint to fully understand the disease process. We are keen to chase more dollars to actually work on this dieback syndrome in detail.

It is an important tree species for many reasons, one of which is the ringtail possum relies on it as a food source.

Phil Beckett January 2, 2013

Hello,as a concerned property owner in the Frankland River district, I have observed the decline of a number of Marri trees on my property at 15 Ward place.
I have noticed the decline of one tree in particular. Unfortunately I recently noticed the health of a Marri tree, nearby, has begun to decline.
Has anyone investigated the possibility of disease transmission by cockatoos?
Especially, when there are large numbers of birds roosting in trees.
My theory comes from observing an increase of white cockatoo numbers in Frankland and the increase in the decline of the Marri trees.
Frankland is experiencing a large flock around the townsite. Could this concentration and high numbers, be of significance,in the transfer of the canker disease?
Might the disease be transferred via the claws of the birds and their tendency to chew branches, etc.?

I would be interested in receiving your reply.

Regards, Phil Beckett

sandy thelander June 7, 2013

We live on a large residential block in Gooseberry Hill.
We have mature marri, jarrah & wandoo trees. At the present time, we are most concerned about the marris; one very large marri tree in particular.
Is there any way that we can boost the tree to help it fight the diseases?
We would be grateful for any advice.
Many birds; insects as well as other wildlife come to visit our garden because of the trees.
Thank you,
Sandy Thelander.

Renee September 4, 2013

To add to these comments we are in the foothills (Helena Valley) and have seen 2 large (mature) Marri's and one Wandoo die on our block in the past 3 years. I've wondered if anyone was taking statistics on the rate of tree death in the Perth Hills, I drive these roads daily and in my lifetime I am noticing a big loss of mature trees here.

David Tripp December 25, 2014

Hi again Giles. This just to ask whether it's the same pathogen that's causing the canker in e.rudis in the SW. It's affecting young trees as much as old, and it's not the psyllid or leaf miner, but in addition to those.

It seems to travel branch by branch so the trees show the whole progression of the problem from a few brown spots through to general discolouration and then total leaf death all at the one time. I've noticed that previously affected very young trees' twigs were covered in canker when they'd died.

Giles Hardy February 3, 2015

David,
Sorry for the late reply. No it is not the same pathogen that is causing canker on E. rudis. I am yet to see cankers in rudis. Note the canker on marri is very specific to the Corymbia and we have never seen it on Eucalyptus species.

I have not seen your branches, but frequently young twigs swell and deform due to insects (I think mainly wasp species) are causing galls. If you take a sharp knife and cut into these you will find (as the right time) the larvae present.

So much is happening to rudis currently, but most of the reports and what I see are due to the lerps.

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