Investigating the current state of knowledge worldwide regarding Neonectria galligena (AP05029)

This is a final research report from Hort Innovation’s historical archives. Please note that as these reports may date back as far as the 1990s, the content and recommendations within them may be superseded by more recent research.

What was it all about?

This project conducted a comprehensive literature review into the pathogen Neonectria galligena, which caused European canker in apples, and undertook a predictive modelling study using the software packages, CLIMATE and CLIMEX, to identify regions in Australia with environmental conditions favourable for establishment and spread of the pathogen.

European canker was one of the most important diseases of pome fruit and many species of hardwood forest trees worldwide. Cankers develop on the woody tissues, girdling and killing branches and, occasionally, the whole tree. The disease was found on apple in Tasmania in 1958 and an extensive eradication program was carried out, resulting in area freedom declared in 1991. At the time, no estimate was made of the cost of this incursion to Australia. However, a realistic comparison could be made with the costs of eradication and surveillance associated with the fireblight outbreak in Victoria in 1997, which was estimated to be A$20 million.

The main findings of this project were:

• N. galligena had been recorded on more than 60 plant species from 20 genera and from climates ranging from sub-arctic (Iceland, Sweden, Canada), temperate (Europe, USA, Chile), arid (Syria, Saudia Arabia, Afghanistan) to tropical (Java, Florida).
• It had the potential to establish in many parts of Australia, particularly the southern and eastern coastal regions. Industries such as apple, pear, walnut, loquat ornamentals and the nurseries that supplied these industries could have all been adversely affected.
• There was no data on the susceptibility or otherwise of Australian native flora. The pathogen had been recorded on three species of New Zealand native flora and it was unknown what the source of the infection was.
• There was no data to support or refute whether latent infection in fruit of New Zealand apple varieties was a potential pathway of N. galligena into Australia. Latent periods in fruit of these varieties had not been studied. There was no information on the role of latent infection in fruit as a source of inoculum, although mummified fruit were a known inoculum source.

A visit in September 2006 to the Applied Plant Science Division, Department of Agriculture and Rural Development, Belfast, Northern Ireland, established dialogue between the research group led by Dr Alistair McCracken and the team at DPI Victoria. Negotiations were underway to conduct a simulated storage experiment in Northern Ireland to investigate incidence of latent infection of N. galligena in the dessert variety, Royal Gala.