2025 situational analysis of pasture dieback in eastern Australia

Abstract

Pasture dieback affects millions of hectares of highly productive grazing land in eastern Australia, specifically north, central and south-eastern Queensland, and north-eastern New South Wales. The impact to grazing industries, including beef, dairy and sheep, is significant. Improved (or sown) tropical and sub-tropical grass species are predominately affected; very few native grasses are impacted. Affected plants initially exhibit leaf discolouration, which culminates in a mosaic of patches of dead grass across a pasture. Temperate grasses and broadleaf plants including annual and perennial legumes are not affected.

Dieback has occurred previously in tropical pastures across Queensland. A large dieback event happened in central Queensland during the 1990s and a much smaller and shorter event occurred in the mid-1920s in south-eastern Queensland. The leading cause of the current situation is the pasture mealybug bug (Heliococcus summervillei), whereas the cause of the 1990s event remains unknown despite research at that time. This indicates potential for a disease complex. Dieback has also been recently reported in tropical pastures across multiple south American countries where varied causes have been purported.

The Department of Primary Industries (DPI) initiated research activities into this condition in 2015 which included: characterising symptom progression, factors affecting disease occurrence, diagnostic pathology, and management options for affected areas. This research has been complimented by similar activities undertaken by other organisations. Research activities were accompanied by an industry engagement program including peer-to-peer learning activities such as group workshops and field days; and published resources including online and print factsheets, articles, videos, podcasts and social media posts. All are available in an online hub (www.futurebeef.com.au/resources/pasture-dieback/).