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Ongoing project

Avocado sunblotch viroid survey (AV18007)

Key research provider: The University of Queensland

What’s it all about?

This investment is surveying for avocado sunblotch viroid in growing regions across Australia, to provide evidence to support declarations of regional or national freedom from the pathogen.

A declaration of ‘pest freedom’ – whether at a farm, region or national level – will facilitate export to countries that have their own domestic industry and may be concerned about the introduction of avocado sunblotch viroid, such as New Zealand. Understanding any current distribution of the viroid will also allow a better assessment of the risk of importing avocados to Australia from countries where the pathogen is common.

Importantly, the work and protocols this investment is establishing – such as its use of databases, its surveillance approaches and its analytical techniques – will have broad applicability across a number of biosecurity threats relevant to the Australian avocado industry, now and into the future.

Substantial progress has been made in the first year of the project, with the completion of sample tests from major nurseries along the eastern seaboard of Australia for avocado sunblotch viroid (ASBVd).

The major intervention point to control ASBVd is at the nursery stage, as the viroid is transmitted at very high rates through seed and can be multiplied if infected budwood is used for propagation or grafting tools become contaminated with sap from an infected tree.

A new avocado plant health scheme operated under the Nursery Industry Accreditation Scheme Australia has commenced, requiring that plants be tested for ASBVd.

The team have completed diagnostic testing on 2,496 plants representing 10 different cultivars from six major nurseries, with all plants demonstrated to be healthy. This result provides great confidence that the avocado industry is well on the journey to achieving freedom from ASBVd.

Good progress has also been made to develop a statistical approach for the retrospective certification of avocado orchards as being free of ASBVd. Specialised modelling work has created a simple-to-use computer program that estimates the levels of confidence that ASBVd will be detected, given nominated incidences of infection and rates of sampling.

The project team continue to engage with industry to share findings as they become available.

Related levy funds

This project is a strategic levy investment in the Hort Innovation Avocado Fund