2017-2020

This project was supported by the Australian Government as part of the Improving Your Local Parks and Environment Program (2017 to 2020) administered by the Department of Industry, Innovation and Science on behalf of the Department of the Environment and Energy (now Department of Agriculture, Water and the Environment).

This project focused on releasing and monitoring progress of the fungus Kordyana brasiliensis on wandering trad in the Dandenong Ranges (2019-20) and throughout Victoria more broadly (2020), in partnership with local community stakeholders (in particular the Community Weed Alliance of the Dandenongs [CWAD], coordinated by Bill Incoll).

Developing release methods

In March 2019, after permission was granted to release the fungus from quarantine, an efficient system was developed to produce wandering trad plants infected with the fungus to have a continuous supply of material for delivery to community members. Following initial trials, two methods were selected for large-scale releases: the ‘bin-inversion’ and ‘planted-stem’ methods.

For the ‘bin-inversion’ method, between 10 and 15 wandering trad leaves infected with the fungus are carefully stuck using Vaseline to the inside-bottom of a large plastic tub (e.g. garbage bin), with the underside of each leaf facing upwards towards the opening. The bin is then inverted over a dense patch of wandering trad growing in cool, moist, shaded habitats for at least 24 hours to allow spores to be discharged from the infected leaves, land on the healthy wandering trad leaves below and infect them.

For the ‘planted-stem’ method, a single stem of wandering trad with several leaves infected with the fungus is planted into moist soil in the centre of a patch of wandering trad, thereby allowing spores to be passively discharged over several weeks and transferred to nearby healthy leaves.

Establishing long-term monitoring plots to measure impacts of the fungus on wandering trad and associated vegetation

In May 2019, the fungus was released using the ‘bin-inversion method’ at each of 15 long-term monitoring plots (6m x 10m in size) established in moist forests of Victoria. Baseline data on the abundance of wandering trad and diversity of native vegetation were collected prior to release of the fungus are each site. Monitoring undertaken between October and December 2019 –approximately five months after the fungus was first released – recorded infection of wandering trad at 60% of the monitoring plots. The fungus was re-released at 10 monitoring plots using a combination of the ‘bin-inversion’ and ‘planted stem’ methods in October 2019 to boost infection levels.

Unfortunately, due to covid-19 travel restrictions, it was not possible for CSIRO field ecologists to revisit the monitoring plots to evaluate establishment and spread of the fungus in 2020. However, visits by Bill Incoll from CWAD indicated that the fungus is beginning to spread widely at several sites.

Releases of the fungus throughout Victoria in partnership with local community organisations

CSIRO held three information sessions in 2018 to showcase the project to local community stakeholders: one hosted by the CWAD (at Birdsland, 31^st January 2018), one hosted by Yarra Ranges Council (Lilydale, 5^th June 2018) and another by Yarra Ranges Landcare Network (Monbulk, 5^th June 2018). Attendance was open to any interested local community stakeholder, weed control contractor or government officer. During these meetings, CSIRO provided attendees with information about the wandering trad fungus, a background to research underpinning its development, progress regarding the risk assessment and application to release the fungus from quarantine, its anticipated post-release impacts on wandering trad and benefits to native vegetation, and how community members would be able to participate in the release program once permission to release the fungus from quarantine was granted.

In 2019, five face-to-face workshops on the biocontrol project were delivered to local community stakeholders across the Dandenong Ranges region of Victoria. During these workshops, attendees were trained in release and monitoring techniques for the fungus. At least one bag containing approximately 10 wandering trad stems infected by the fungus were given to each of workshop participants to make releases at their trad-infested sites. Two attendees were provided with bags of at least 100 infected stems each, allowing for several releases to be made. Overall, we estimate that approximately 830 infected stems were provided to 63 unique attendees at these face-to-face workshops.

Between September 2019 and October 2020, CSIRO posted approximately 940 additional wandering trad stems infected by the fungus to 22 community participants, many of whom were unable to attend the face-to-face workshops in 2019. During 2020, CWAD set up 13 nursery sites with 990 infected stems sent by CSIRO, to provide sources of infected material in the future to make additional releases of the fungus in the region. The fungus has successfully established at these nursery sites (Bill Incoll, pers. comm.).