Meat & Livestock Australia are investigating mealybugs as a secondary infestation to pasture dieback as their research into the broad scale problem continues.
Early indications from lab results and field observations indicate a fungus is the primary cause of the wind-borne pasture dieback which has reportedly spread as far west as Roma.
Ahead of an MLA meeting with researchers tomorrow, the Queensland Country Life can reveal information from recent findings provided to AgForce members.
In it, MLA indicated they were monitoring mealybugs after increased sightings in the Callide/Dawson, Gogango, Biggenden, Gin Gin and Gympie areas recently.
The MLA statement said they were confident insect products from the likes of Hortus Technical Services in Bundaberg would efficiently attack mealybug.
“At this stage we do not think mealybug are the root cause of dieback and are more likely to be a secondary infestation but we are still investigating and keeping an open mind,” it read.
MLA are still receiving a “handful” of pasture dieback reports from landholders each week or fortnight.
MLA R&D program manager Doug McNicholl said the mealybugs were effectively swooping in when the plant’s immune system was deficient.
“Whether it is dieback or not a plant that has diminishing health is going to be susceptible to secondary parasites or fungus,” he said.
“Whether it is dieback that is lowering the plant immune insect or not, it appears mealybugs are moving in as a result.”
In the meantime, a number of pasture dieback treatments are being tested with fire proving to be “sometimes” effective while replanting an alternative crop (wheat or rye grain) hasn’t resulted in the alternative crop being impacted.
Intervention trials on a number of properties in the Dawson and Burnett regions are believed to be looking “promising” with more time needed to assess if they are worth undertaking.
Results from a synthetic and natural fungicide treatment are expected in May or June while those of a cycling land use trial of alternating feedbase to crop are expected in December.
A team of external researchers with backgrounds in agronomy, plant pathology and microbiology, have been working with MLA to identify the cause of the problem which has impacted up to 90 per cent of some producer’s pastures.
The team have been taking field samples, replicating their growing environment in a lab and testing a number of pathogens to identify the one responsible.
Over the past two and a half years, areas from Cairns down to Beaudesert have been affected with both introduced and native grasses at risk.