Classification of the onion rust complex and development of rapid diagnostic assays (VN13001)

What was it all about?

With onion rust identified as a biosecurity risk to the industry, this project sought to determine which rusts infect the onion family in Australia and overseas. The team then looked at reliable diagnostic markers, to aid future biosecurity efforts for the Australian industry.

Looking at samples of onion rust from Australia and abroad, the research team provided an overview of the diversity of onion rusts in Australia, confirming that Puccinia porri – a rust commonly found in Europe and the Middle East – has not been found in Australia. A rapid, molecular diagnostic test to aid identification has now been devised and tested for this species.

Another rust, restricted only to chive, was found only once in Australia, some decades ago. The researchers suggested that this rust, Puccinia mixta, may have failed to establish in the country.

Of three Puccinia alli-like species identified in the project, two were found in Australia. The third, a garlic-infecting type found in California, was not found.

Importantly, the project was unable to find any specimens of rust disease on bulb onion, either from Australia, overseas or in a literature search, with no recent records of disease on bulb onions.

The project concludes that although rust is presently not a serious threat to the bulb onion industry, vigilance needs to be maintained. The rust classification system developed in the project will help with correct identification.