Mealybugs and viruses at pasture dieback trial

More than 30 people attended the unique pasture dieback trial located on a commercial property near Boonah in June.

Department of Agriculture and Fisheries (DAF) Principal Pasture Agronomist, Gavin Peck, said “While there are other dieback field trials in Queensland, none have applied pasture mealy bug directly to plots or have as many grass species and varieties.”

Attendees saw the impact of pasture dieback on 29 grass varieties with 7 displaying severe damage and death after mealy bugs were applied.

The pasture dieback trial held on a commercial property at Boonah is unique due to the number of pasture species being assessed for susceptibility and mealybugs being directly applied to each variety.

A highlight of the day was hearing from DAF Principal Entomologist, Melina Miles. “Pasture mealybugs cause pasture dieback symptoms through their feeding damage” Ms Miles said. “Mealybugs feed on leaves and roots of grasses. The pasture dieback symptoms are the plant’s response to the feeding damage, resulting in plant stress symptoms of reddening and, or yellowing. It can also result in plant death” she said.

Mealy bug
Despite their small size, mealybugs can induce remarkable damage to tropical pastures.

Attendees also had the privilege of hearing from Senior Plant Pathologist, Dr Kathy Crew. “Viruses may also play a role in pasture dieback,” Dr Crew told field day attendees. She continued, “A known virus that causes disease symptoms similar to pasture dieback in cereal crops in southern states was detected at this site, as well as previously undescribed viruses that are likely transmitted by mealybugs.”

Dr Crew also noted, “While the viruses were found on the site, the wider distribution of these viruses and their role in pasture dieback requires further study.”

Pasture dieback impacted grasses
Unthrifty growth, followed by the yellowing and reddening of leaves are typical symptoms of pasture dieback.

Research will continue at this trial site to provide more information on the tolerance of grass varieties to pasture mealybug and pasture dieback.

This trial has been funded by the Queensland Government since 2019. The trial is continuing as part of a new pasture research and extension program co-funded by the Queensland Government and Meat & Livestock Australia through the MLA Donor Company.

More information about pasture dieback

Signs and symptoms →

Management options →