Researchers on the case

Pasture dieback researchers working to find cause of mystery killer


Multimedia
Aa

From insects to fungi, no stone is being left unturned in the search for the cause of pasture dieback.

Aa
PASTURE MYSTERY: Anthony Young, Shane Campbell, Hank Xu and Melody Thomson inspecting a pasture dieback site on the UQ Gatton campus.

PASTURE MYSTERY: Anthony Young, Shane Campbell, Hank Xu and Melody Thomson inspecting a pasture dieback site on the UQ Gatton campus.

Researchers looking for clues into the mysterious pasture dieback threatening Queensland producers' livelihoods are trying to confirm if a biological agent is behind the issue.

The spread of dieback, which causes large areas of pasture to unexpectedly die, has seen the Department of Agriculture and Fisheries, Meat and Livestock Australia and the University of Queensland all get involved to try to find first a cause, and then a cure.

Pasture dieback had been affecting producers across Queensland since the early 1990s with central Queensland, the Lockyer Valley and the Burnett region all struck by the mysterious killer. While the condition was initially noticed in buffel grass, it has since affected species including creeping blue grass, Rhodes grass and Mitchell grass.

The federal government has recently poured an extra $3 million into pasture dieback research, with MLA matching the amount.

University of Queensland researchers based out of Gatton noticed pasture dieback on their own campus in early 2018.

"The farm manager had mentioned he had seen a couple of patches of grass that just didn't look right and started to be losing vigour and condition and eventually dying," UQ pasture agronomist Shane Campbell said.

SEARCH FOR ANSWERS: Honours student Melody Thomson is part of the UQ team.

SEARCH FOR ANSWERS: Honours student Melody Thomson is part of the UQ team.

"Then we got really good rain in March last year, not dissimilar to what we've had recently.

"It started to happen really quickly then, over about a month period we noticed these patches expanding and really starting to show symptoms of dieback and had some of those distinctive characteristics that were in other locations that were being observed a bit north from here." 

UQ School of Agriculture and Food Sciences lecturer Anthony Young said they were trying to systematically exclude anything that might be contributing to pasture dieback. 

Early stages of pasture dieback at the UQ Gatton campus.

Early stages of pasture dieback at the UQ Gatton campus.

Part of the work involves figuring out whether the dieback could be transmitted to other grasses, to determine whether the root cause is one or several biological agents.

"There's a lot of confusion in the industry and farmers obviously want answers," Dr Young said.

"We'd like to just go back to the basics, get the science done from the grassroots as it were and hopefully come up with an identity of things that could be causing pasture dieback.

"But once we have that, that's only 10 per cent of the problem because we then have to work out how to manage it into the future.

"We're seeing pasture dieback on such a different range of soils from sandy soils to heavy clays...  so many different soil types and so many different grass species that you wouldn't think it's got anything to do with the actual properties of the soil, but we haven't ruled that out either." 

The pasture dieback also clears the way for broadleaf weed species to take over the space, with Mexican poppies, wild cottons, and thistles all coming into affected areas.

Honours student Melody Thomson has been researching whether the presence of certain insects, such as mealybug, was associated with dieback, while masters student Hank Xu is looking at fungi present at pasture dieback sites.

"Everything is on the table at the moment," Ms Thomson said.

"I'm considering [mealybug] but I'm also looking at two or three other big insect pests that could be contributing to this."

EXAMINING EVIDENCE: Hank Xu and Anthony Young examining fungi collected from a pasture dieback site.

EXAMINING EVIDENCE: Hank Xu and Anthony Young examining fungi collected from a pasture dieback site.

MLA researchers have previously identified that mealybugs, a sap-sucking insect, are associated with pasture dieback but it's not known whether they are the actual cause.

Dr Young said it was possible that the weakened state of the plants simply meant they were less able to defend themselves against insect infestation.

"We're not saying mealybugs aren't the cause of the dieback but we're just making sure we're not confounding the cause with the symptoms," he said.

Fungi collected by researchers from pasture dieback sites.

Fungi collected by researchers from pasture dieback sites.

Meanwhile Dr Ammar Abdul Aziz is using satellite imagery to try to figure out an early detection system for pasture dieback.

While he has initially focused on the UQ Gatton sites, he's now looking to home in on other areas to collect enough data to conduct detailed analysis. 

Using historic satellite imaging, he aims to identify the different stages of dieback in affected pastures.

The team wants to hear from more producers who believe their properties have been affected to find further sites to collect samples. Producers are also urged to contact DAF and MLA.

Aa

From the front page

Sponsored by