Across large areas of the Monaro region of NSW, the trees are dying. Over the last decade, the Manna Gums or Eucalyptus viminalis have been gradually declining in health and now stand like skeletons in huge tree graveyards. But what is causing this mass dieback? Catherine Ross, an honours student, was given the task of investigating this intriguing mystery.

The Manna Gum population plays an incredibly important roll in the Monaro region. Much of the region is considered to be naturally treeless or has been cleared since European settlement, so the remaining patches of Manna Gum Woodland are important refuges for wildlife. They also act as shelter for stock and prevent erosion. The dieback: canopy thinning, defoliation, dead branches and eventual tree death, is a major problem.

Catherine’s blog, Scribbly Gum, explains the processes that she went through to understand the cause of the dieback. She investigated three main ‘suspects’ (causes of the dieback); agricultural practices, fire exclusion and the climate. Catherine also discusses the possible management strategies including stem-injected pesticides and assisted migration.

Study site comparison

Two sites that Catherine studied – although the one on the left is agricultural pasture, and the other isn’t, they had the same severity of dieback

To find out about Catherine’s ‘Murder Investigation’ into the dieback of the Monaro Manna Gum, and her conclusions,  you can read her blog here.

Article adapted from Scribbly Gum Blog. Photos from Scribbly Gum Blog.

Banner Image: Flickr. (2019). Scribbly Gum scribbles. [online] Available at: