Community involvement in large-scale releases of the Crofton weed rust fungus in 2015-16
Crofton weed plants infected by the rust fungus were used for the large-scale community-based release program because simply transferring rust-infected leaves to a new site was found to be highly unlikely to lead to establishment of the fungus. The fungus shuts down very quickly once infected material is removed from a plant and thus does not produce the necessary spores for new infections to occur.
Rust-infected plants grown in pasteurised soil or in rock wool were distributed to community members at field events or via the post, respectively.
Release of the rust fungus
Three to four rust-infected plants in a plastic-lined box or in individual milkshake containers, obtained at a field event or via the post, were placed within a dense stand of Crofton weed in the shade, where there was no chance of livestock grazing on them. Water was added to the containers to ensure plants remained alive for 2-3 weeks. The release area was identified by attaching a piece of flagging tape on a nearby bush or tree, or using another form of marker to ensure the area could be relocated for monitoring. Plants were not transplanted in the ground as this was deemed too stressful for them. Community members were asked to revisit release sites at at 4-5 weeks and 3 months after release to inspect for rust symptoms on field-growing Crofton weed plants, record observations and provide feedback to the research team.