What is dieback?

Dieback refers to the gradual deterioration of health in trees, sometimes leading to tree death. Dieback is usually caused by a combination of factors, such as disease and pathogens, insect attack and/or stressful climate conditions. Dieback in Australia is not a new issue; hardy native trees have historically been able to withstand stressors throughout their life (for example, droughts, water stress, disease and insect attack).

More recent reports of dieback, both globally and in the ACT, now consider that additional stress from climate change contributes to tree mortality.

While dieback affects many species in the ACT and NSW regions (including Eucalyptus viminalis, E.bridgesiana and E. melliodora), recent observations supported by satellite imagery have recognised a significant increase in the incidence of dieback in Blakely’s Red Gum (E. blakelyi). Dieback of Blakely’s Red Gum appears to affect any age class and is occurring across rural landscapes, urban environments and reserves within the ACT. High rates of mortality among younger trees have resulted in a lack of successful maturation across the ACT landscape. If younger trees are unable to replace the older, dying trees, the population will slowly thin out.

A great deal of uncertainty surrounds the cause of Blakely’s Red Gum dieback in the ACT, and is thought to be the result of a number of stress-inducing factors, impacts associated with climate change and reduced resilience within the landscape.

A multi-disciplinary approach to further research regarding this issue is being discussed within the ACT Government, with the aim of determining the root causes and identifying potential future actions to improve the health of Blakely’s Red Gum.