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Research into pasture dieback continues

21 May 2020

A new round of pasture dieback research and extension projects will shortly kick-off in Queensland and New South Wales, as part of MLA’s coordinated response to tackling the destructive condition.

Pasture dieback is a condition causing death of grass pastures across a range of sown and native species. The exact cause or causes have not yet been established.

MLA, Queensland Department of Agriculture and Fisheries (DAF) and NSW Department of Primary Industries (NSW DPI) are working alongside the red meat industry and stakeholders to ensure ongoing investment in pasture dieback research is effective, well-coordinated and clearly communicated.

DAF, NSW DPI and MLA continue to investigate and invest in possible causes and management options that red meat producers can implement to restore pasture productivity.

Complementing the research already underway around investigating Mealybugs as a likely primary causative agent, the new projects planned for Queensland will complement the existing and planned research program being conducted by DAF, NSW DPI and others into this important issue.

DAF Senior Agronomist – Sown Pastures, Stuart Buck, and NSW DPI Senior Research Scientist, Dr Suzanne Boschma, discuss what is happening in each state.

Q: Where has pasture dieback been identified and what species is it affecting?

Stuart: Pasture dieback is prevalent across northern, central and south-east Queensland and every known sown pasture species has been affected, including buffel grass, Rhodes grass, panics, paspalums, signal grasses, urochloas, and bluegrass. There have also been significant but relatively small areas of dieback in native pastures.

Suzanne: We had our first report of suspected pasture dieback in autumn 2019, but drought conditions made positive identification impossible. We were able to confirm it on the north coast of NSW in March this year. It has mostly been found in broad-leaved paspalum with a number of reports in other grasses including kikuyu, Rhodes grass and setaria. At the moment, it seems to be more prevalent on the native/naturalised pasture country.

Q: What pasture dieback research, development and extension has been undertaken in each state to date?

Stuart: In Queensland, we have had an extensive program running for more than two years now with four key theme areas – engagement and extension; diagnostic; characterisation; and management options.

Our diagnostics program is examining all potential causes including insects, fungi, viruses, and bacteria. Regarding insects, we have a particular focus on investigating the role pasture mealybug is playing in dieback, and we are collaborating with the University of Queensland (UQ) team at Gatton to determine the incidence of ground pearl.

One of our key messages is that until a plant actually progresses through the full spectrum of symptoms including yellowing and reddening, poor growth, then death, it is very difficult to ascertain if it is dieback, or not, that is killing it. There are a range of environmental and biotic factors which can cause similar symptoms. As a result, a focus with our characterisation work is to define the characteristics that are particular to dieback.

We have visited close to 80 sites across Queensland affected by dieback, surveying and recording the situation to investigate what might be pre-disposing pastures to dieback. We also have a pot trial in Rockhampton, to more clearly define what dieback is and is not.

Looking at management options, we have a field trial at Brian Pastures Research Facility near Gayndah in the North Burnett region, investigating the impact of a range of options to restore productivity including forages, cultivation with and without re-seeding pasture, pesticides, fertiliser, burning or slashing.

We are also conducting grass tolerance trials, where we have a replicated trial including 17 different grass species, three of which were sown with either coated and uncoated seed, with five legumes as comparators. So far there are differences across grass species, but all legumes are generally going very well. We also have 26 grass species recently planted at another site near Boonah in southern Queensland.

The diagnostic team has been undertaking a lot of field work in the last two months, collecting plant and soil samples. They are processing those samples and the results have not come in yet.

Suzanne: We have been raising awareness of pasture dieback for about 12 months, suggesting producers check their pastures for any changes. We have developed a number of resources for producers and advisors which are available on the pasture dieback page of NSW DPI’s website. We have also added links to other dieback resources including DAF and MLA.

NSW DPI are working closely with North Coast Local Land Services, who have been visiting sites and collecting samples from affected and non-affected sites. The samples are being analysed by NSW DPI.

We are currently developing resources about alternative forage options and mealybugs, which have been found at a number of the sites. To maintain productivity in dieback affected areas, alternative forages are the best option because all of our commonly sown summer-growing perennial grasses are susceptible. Producers will be able to review the information then discuss with their local advisor the best species and cultivars for their situation.

Q: What are the new project areas being proposed with support from MLA?

Stuart: MLA funding will help us build on our diagnostic program to analyse samples we already have collected and do a lot more collections from other sites to get a broader picture across the State. We are also very keen to link in with the work Suzanne and NSW DPI is doing where appropriate.

We want to do more metagenomic work collaborating with The University of Queensland (UQ), and collaborate closely with UQ Gatton on ground pearl research.

The funding will help us continue our mealybug research. We have conducted a number of glasshouse studies and now want to move that out into the field to verify the glasshouse results.

With all producers impacted by pasture dieback asking what they can do to restore productivity, the MLA funding will enable us to establish a producer group that we can upskill and utilise as a conduit to help get research information back out to producers.

We also aim to use the funding to establish another field site and satellite sites to replicate what we are doing at Brian Pastures, looking at different management options to restore pasture productivity.

Suzanne: MLA funding will enable NSW DPI and Local Land Services (LLS) to work on three things. Firstly, we will undertake diagnostics to support and value add to the work others are doing and approach, what appears to be an interaction of factors, with fresh eyes.

The second component is working with producers and advisors to understand pasture dieback, increase surveillance, and develop and test some strategies and alternative forages to provide feed for livestock.

Producers are concerned about the loss of productivity. North Coast LLS will work through and identify options with producer groups and trial some on-farm. Northern NSW and Southern Queensland have the advantage of receiving both summer and winter rainfall, so we are able to grow both summer and winter species.

The third component of our project with MLA is to prepare sites to conduct more comprehensive testing of a range of summer and winter growing pasture, forage and crop species. To date, all evaluation has been of summer-growing perennial grasses with limited or no information on the susceptibility of annual grasses and winter-growing species.

Q: If producers are concerned they have pasture dieback on their property, what should they do?

Stuart: In Queensland, contact the DAF customer call centre on 13 25 23.

Suzanne: In NSW, contact the Exotic Plant Pest hotline on 1800 084 881 or email: biosecurity@dpi.nsw.gov.au with a clear photo and your contact details.