A naturally occurring fungus is being harnessed to tackle Noogoora burr, an invasive weed which causes major impacts on agriculture and the environment in eastern Australia.
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NSW Department of Primary Industries (DPI) research agronomist, Graham Charles, said the project has identified a fungal pathogen, Alternaria zinniae, as a potential bio-herbicide.
“Glasshouse trials have found the fungus will infect Noogoora burr, but it requires an extended period of dew or surface moisture for maximum impact,” Mr Charles said.
“In collaboration with Melbourne University, we are developing complex emulsion formulations of fungal spores, which retain moisture to enhance infection of the weeds over time.
“Noogoora burr poses a unique conundrum due to its many species and complex DNA – we need to ensure the fungus is effective across all species.
“DNA sequencing is helping clarify differences between four species within what is called the Noogoora burr complex, Noogoora burr Xanthium occidentale, Hunter burr X. italicum, Californian burr X. orientale, South American burr X. cavanillesii and interspecific hybrids.”
To date about 100 samples have been collected from NSW and Queensland.
In preliminary DNA barcoding and population genetics work NSW DPI and the University of Queensland found Hunter burr and Noogoora burr are genetically different but hybrids of both exist.
This information will be useful in understanding any future species-specific responses to the new bio-herbicide.
Noogoora burr also hosts pest insect species and fungal pathogens which affect cotton, including environmental pests and Verticillium dahliae which causes Verticillium wilt – a major concern for the cotton industry, which is extending into southern NSW.
NSW DPI cotton pathologists are using molecular techniques to determine what strain of V. dahliae is hosted by each of the species in the Noogoora burr complex.
