Pasture Dieback

MLA is working with industry bodies, state departments and researchers across affected regions to ensure a coordinated approach to investment in research, development, extension and adoption is being taken to support producers in combatting dieback.

The Queensland Department of Agriculture and Fisheries and NSW Department of Primary Industries have key roles within their state jurisdictions to undertake measures to control the outbreak of pasture dieback. Through its industry-focused response, MLA is supporting these organisations to do so.

In mid-2019, the Department of Agriculture, Water and the Environment awarded a $2.7 million grant to MLA to undertake research and development activities to further understand pasture dieback, with a focus on determining the role of mealybugs in the presence of dieback-affected pastures. MLA has committed to matching this grant with producer levy investment to ensure solutions-focused research, development and adoption activities are undertaken to support the industry.

MLA’s plan on a page summarises the federal grant work plan and MLA’s direction in its response to pasture dieback.

A central component of investment so far has centred around understanding mealybugs as the leading causal agent of dieback. However, MLA’s understanding is that there are other secondary factors which contribute to the episodic outbreaks of dieback that occur. Some of the new projects are focused on understanding these factors to better tailor solutions while investigations into the mealybug continue.

Research partners:

• Queensland Department of Agriculture and Fisheries (QDAF)
• New South Wales Department of Primary Industries (NSW DPI)
• Applied Horticulture Research
• University of Queensland (UQ)
• Queensland University of Technology (QUT).

MLA's pasture dieback governance

Past work conducted on pasture dieback:

• Field trials to test interventions – Cultivating and re-sowing pasture with insecticide treated seed and fertiliser gave the best response with no sign of dieback recurring.
• Survey of soils and plants from dieback-affected areas to determine role of soil-based organisms – fungal pathogens are not the primary cause of pasture dieback.
• Studies examining establishment and spread of pasture dieback – how recent weather, soil conditions and other factors may be related to spread.
• Genomic DNA investigation of affected soils.
• Satellite mapping to detect dieback – potential to build a “trend pattern”. These patterns point towards rain as having a direct effect on dieback.
• Hyperspectral imaging – to analyse dieback-affected grasses for early detection. Variability is apparent, with additional lab and field work required.
• Mealybug studies – mealybugs have been widely detected on dieback pastures. The biology of the mealybug and management is being investigated.
• Evaluation of pasture species and resistance to mealybugs – legumes are not affected; spring and summer-sown forage crops are a short-term solution.
• Producer interviews – to collect information about how dieback was occurring on each property, and any observations by producers on potential causes and control practices which have been trialled. 

Current projects:*

• QUT – Understanding the mealybug life cycle and history. This project will look at the biology of the mealybug – growth, reproduction, seasonal interaction with grasses, to help understand possible natural enemies, particularly possible parasitoids and pathogens.
• QUT – Bioassays and controls. This project will provide definitive tests to determine the progress of dieback in a range of grasses from initial infestation to death of the grass, and any association with pathogens that may lead to dieback. This information will assist with the screening of potential controls for mealybugs.
• QUT – Evaluation of potential for use of endophytes as a control measure. This project aims to identify grass varieties tolerant of pasture dieback, with or without endophytes, to regenerate pastures and enable long-term recovery.
• QDAF – Grazier engagement to increase knowledge, skills and ability to combat pasture dieback. The project will facilitate the formation of a red meat producer group in central Queensland to build knowledge and skills to implement changes on-farm to better manage pasture dieback impacts.
• QDAF – Comprehensive diagnostic analysis of pasture affected dieback. This project will explore and better understand other possible factors causing pasture dieback outbreaks.
• Applied Horticulture Research – Management options and species evaluation to increase productivity in dieback affected pastures. This project will reassess MLA-funded field trials after two years to quantify any longer-term benefits and evaluate pasture species and/or varieties with reported tolerance to pasture dieback which producers could use to replant dieback-affected pastures.
• UQ – Determining the role of ground pearls. The project will determine if the presence of ground pearls is consistent across dieback sites and understand what role they may have in causing dieback.
• QUT – Spatio-temporal prediction of pasture dieback using UAVs and remote sensing. This proof of concept project will integrate remotely sensed imagery from unmanned aerial vehicles (UAVs) and satellite-based platforms to identify spectral signatures of dieback for cost effective identification, mapping and monitoring over time and at scale using satellite-based systems.
• QUT – Rapid diagnosis of pasture dieback using SIFT-MS. This project will test the proof of concept of the rapid analysis of Volatile Organic Compounds (VOC) and chemical markers detected by Mass Spectrometry (MS) for the rapid identification of pasture dieback in both laboratory-induced dieback (using mealybugs) and on field samples using a portable device for gas collection.

* Project partners work together across affected sites and collaboration occurs when work overlaps and interlinks. MLA’s role is to facilitate this collaboration. Protocols will be matched across projects for consistent results.

Read this article for new insights to tackle pasture dieback