Botanic Gardens Trust, Sydney, Australia

Plant Pathology and Mycology 2012-2013

Zoe-Joy Newby - PhD Candidate; Dr Matthew Laurence -  Diagnostics and Facilities Coordinator; Dr Edward Liew - Manager Plant Pathology

The Plant Pathology and Mycology team continued research activities in documenting and describing foliar diseases of Proteaceae and Myrtaceae; describing new Fusarium species; resolving the phylogenetic relationships of Puccinia psidii (eucalyptus rust, myrtle rust or guava rust) within the Pucciniales; modelling disease risks of Phytophthora Dieback in the Greater Blue Mountains World Heritage Area (GBMWHA), including management of the disease at the Wollemi pine site, and investigating management strategies for a range of horticultural diseases.

Interesting results were obtained from extensive disease survey work conducted over the last two years (see research highlight), involving bulk processing of samples in the laboratory, which benefited greatly from our volunteer programs.

Three new species of Fusarium were described, F. werrikimbe, F. lyarnte and F. burgessii, from natural ecosystems of Australia, the former two associated with indigenous grasses while the latter isolated from natural soils. F. burgessii represents a new lineage within the genus, comprising not less than three distinct species.

A new project was commenced investigating disease management of watermelon wilt by understanding the pathogen biotype, diversity and origin. Disease surveys and pathogen sampling were conducted in Queensland, NSW and the Northern Territory.

Research Highlight

As part of PhD student Zoe-Joy Newby’s work on modelling risk of Phytophthora in the Greater Blue Mountains World Heritage Area (GBMWHA) reported in 2010-2011, intensive sampling work was conducted across the GBMWHA. Phytophthora cinnamomi was found to be most prevalent in the upper parts of the Blue Mountains National Park, typically around the high visitation areas, such as those at Echo Point, Leura and Katoomba. Interestingly, P. cinnamomi was also found in some of the more remote locations within the Blue Mountains and the Wollemi NPs, which indicates that the pathogen has possibly been present in the region for a number of decades. Given that the area has an extensive history of mining, agriculture, tourism, recreation and military activities, the wide distribution of the pathogen is understandable due to the opportunity for spread. Not surprisingly, areas that are least accessed today generally have the lowest P. cinnamomi incidence, most notably the Natti NP.

The sampling results were used to construct a risk assessment for Phytophthora Dieback in the GBMWHA. The potential distribution of P. cinnamomi was modelled using a variety of climatic and environmental parameters. The results indicated that P. cinnamomi was most likely to occur at higher elevations of the GBMWHA in a north-south direction across the top of the Great Dividing Range, where soil, rainfall and temperature are most appropriate for the pathogen. A distribution map of approximately 130 susceptible species in the GBMWHA were also modelled and combined with the predicted distribution of P. cinnamomi. The final map of Phytophthora Dieback highlights the area above the Grose Valley and Jamison Valley, as well as along the Kings Tablelands, to most likely experience Phytophthora Dieback based on the presence of the pathogen and hosts. These areas are incidentally all central to Blue Mountains tourism.

This work has been conducted in close collaboration with the Parks and Wildlife Group in the Office of Environment and Heritage to facilitate prioritisation in disease management.






Figure 1. Zoe-Joy sampling in Burragorang Valley, Natti NP

Figure 2. Dieback in dry sclerophyll vegetation in the Blue Mountains NP.

Figure 3. Model of predicted Phytophthora dieback distribution in the GBMWHA. The model includes a 100 km buffer beyond the WHA boundary.