Phosphite treatments are currently being applied to control dieback in a large important patch of Banksia Woodland in Keysbrook, with promising signs of successful control.

Our Banksia Woodland and Black Cockatoo Project, along with Landcare Serpentine Jarrahdale, recently supported phosphite treatments along 4.4km of dieback front within a 100ha patch of Banksia Woodland. Treatments have been on-going at the site since 2006, with the latest treatment and several previous treatments undertaken by Glevan Consulting.

Although Phytophthora cannot be eliminated from a site once infested, mitigating the impacts on vegetation is possible through phosphite applications. Phosphite is a non-hazardous and biodegradable fungicide that suppresses the pathogen and boosts the plant’s natural defence system. It can be applied through spraying or stem injections of infected plants and is proving effective at controlling the spread of the disease in Banksia Woodland.

Symptoms indicate that old established infestations have been contained, as the dieback front has not moved in the past three treatment events over 10 years. In some patches that were bare ground two decades ago due to Phytophthora dieback, juvenile Banksia ilicifolia are now recruiting naturally and flourishing. This suggests that repeat Phosphite treatments are working, successfully controlling the spread and impact of the disease. Newly established infestations are more difficult to control and move rapidly through infected areas. Considerable on-going investment is required to control dieback in infected Woodlands, however, there is hope that treatments are becoming more effective with time.

We thank the landholders’ commitment to protecting threatened Banksia Woodlands, Landcare SJ and several other local NRM groups for persistent efforts in securing funding for dieback treatments.

This project was supported by the World for Woodlands and Protecting WA’s Black Cockatoos Projects through funding from the Australian Government, with additional funding from Landcare SJ.

We acknowledge the Noongar people as Traditional Custodians of this land and pay our respects to all Elders past and present