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Finally, A Friendly Rust on Aotea

Tradescantia Yellow Spot Fungus is known to be an effective Biocontrol agent against the very aggressive pest plant Tradescantia fluminensis better known as ‘Wandering Willie‘ or ‘Trad’. 

Below is a photo of the recent discovery made by Senior Conservation Advisor Niklas and Motairehe Ltd team members while doing Pest Plant mahi on the island. Two locations have been recorded in the north of Aotea, with hopefully more to come!  

The fungal pathogen, native to Brazil, is host-specific meaning it only impacts tradescantia and is no risk to other species. Tradescantia is identified as a pest plant in the Auckland Regional Pest Management Plan 2020-2030, and eradication is tackled under a whole-of-region sustained control programme, which aims to reduce the spread and impact of the pest plant.

Yellow spot fungus, in conjunction with the tradescantia leaf beetle which is not currently recorded on the Island, make the dream team Biocontrol duo in the fight against Tradescantia. The tradescantia leaf beetle is native to south-eastern Brazil and north-eastern Argentina. The adults chew the edges of the leaves and can consume entire leaves. However, the main damage is caused by larvae which graze the epidermal tissue off the leaves, mostly on the undersides, and can skeletonise them. Again, the leaf beetle is highly host-specific and it is very unlikely that anything other than tradescantia (Tradescantia fluminensis) and closely-related T. albiflora will be attacked. 

Landcare research image: Adult tradescantia leaf beetle resting on upper leaves.

If you see any observations of Yellow Spot Fungus on Tradescantia make sure you record it on the I-naturalist ‘Aotea Biocontrol Project’.

A Timelapse view of Biocontrol

For more information on Yellow Spot Fungus and the Tradescantia leaf beetle visit: 

Tradescantia yellow leaf spot fungus

Tradescantia leaf beetle

Article and images supplied by Niklas Erikson, Senior Conservation Advisor at Auckland Council


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