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Mystery of tree dieback near Bordertown solved
A 30-year mystery surrounding the deaths of hundreds of thousands of native trees across Australia has been solved following ground-breaking scientific research into a fatal plant dieback disease.
In 1975 beekeeper Geoff Cotton was the first to notice a steady decline in the health of river red gums near Mundulla, a small rural community 10 kilometres southwest of Bordertown in South Australia.
'Mundulla Yellows,' as the syndrome became known, first appears as a yellowing of the leaves on a variety of native tree types including eucalypt, banksia and acacia.
Funding
A few years ago the Victorian Department of Primary Industries decided to test the theory that a virus was to blame for Mundulla Yellows. With funding from the Australian Government and support from the Glenelg Hopkins Catchment Management Authority (CMA) researchers set about discovering the true cause of the devastating condition.
Activities
After systematic research with support from other sources such as the South Australian Department of Environment and Heritage, scientists discovered that a soil problem was the likely trigger.
Project Leader Dr Jo Luck is a molecular plant pathologist whose team's pioneering research helped lift the lid on the earthly secret.
"Not only have we discovered the cause of this terrible decline, we're also investigating a range of treatments for sick trees that are looking very promising," Jo said.
The research team - Dr Rosa Crnov, Barbara Czerniakowski and Ian Smith - collected soil samples from 10 sites at Mundulla and Lara, near Geelong in Victoria. Half the sites contained trees that were affected with typical symptoms, while the remainder contained trees with no symptoms.
Healthy seeds collected from river red gums in the Barmah State Forest were then planted into the collected soil. The results were astonishing. Seedlings that emerged from the soil collected from under the sick trees were yellow, stunted and distorted while those that grew from the soil collected beneath healthy trees were green, strong and well.
After searching for reasons why the health of the soil and trees was changing, Barbara believes that the increased levels of carbon dioxide in the air - which dramatically rose at about the same time as the tree decline phenomenon began - may be involved.
Achievements
Already the project team has found a way to reverse Mundulla Yellows symptoms by injecting sick trees with an iron supplement.
"This is encouraging but we hope to develop a variety of management options that deal with the causes, not just the symptoms." Jo said.
More information
- Dr Jo Luck, Department of Primary Industries Statewide Leader Bacteriology and Virology: (03) 9210 9248 or jo.luck@dpi.vic.gov.au
- Department of Primary Industries
- Glenelg Hopkins CMA
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