Assessment of eucalyptus rust as a pathogen of Eucalyptus species and other Myrtaceae, and development of sensitive methods for its detection in germplasm

FST/1996/206: Assessment of eucalyptus rust as a pathogen of Eucalyptus species and other Myrtaceae, and development of sensitive methods for its detection in germplasm

South Africa

CSIRO Forestry and Forest Products, Australia

Dr Ken Old
Phone: (02) 6236-3284
Fax:
Email: kmold@webone.com.au

• Federal University of Vicosa, Brazil
• University of Pretoria, South Africa
• CSIRO Plant Industry, Australia

$598,373

01/07/2000 - 30/06/2003

Dr John Fryer

Puccinia psidii is an important shoot and leaf rust pathogen of members of the Myrtaceae family, which consists of approximately 155 genera, including eucalypts. The pathogen is regarded as the most serious threat to eucalypt plantations worldwide. It could also cause serious damage to natural ecosystems that include Myrtaceae.

Puccinia psidii is currently restricted in its distribution to South and Central America, the Caribbean and Florida. It has been very damaging to industries based on susceptible crops in the Caribbean and Brazil and most recently in eucalypt plantations in Argentina.

The pathogen has shown a capacity for international dispersal and is considered a major threat to the safe movement of germplasm of eucalypts. The Myrtaceae family is distributed in Australia, Southeast Asia, New Caledonia and other Pacific Islands, South and Central America, and southern Africa. If P. psidiiwere to enter Australia, for example, the effects on hardwood plantations and native vegetation would be severe.

More information is required to assess the susceptibility of a range of Australian Myrtaceae to P. psidii, particularly economically important genera including Eucalyptus, Melaleuca (tea tree), Eugenia, Syzygium and Callistemon. A better understanding of the variations in rust is also required to help prepare pest risk analyses relating to Australia and South Africa. There is also a need for diagnostic methods to enable the rapid detection of rust in germplasm.

The project has five main aims:
(i) To evaluate the susceptibility of eucalypts and other members of the Myrtaceae family to the shoot and leaf rust pathogen Puccinia psidii.
(ii) To assess the pathogenic and life cycle variation in the rust from various hosts through cross inoculation.
(iii) To prepare maps indicating eucalypt areas of high, medium and low risk from P. psidii using climate interpolation and disease hazard mapping methods.
(iv) To prepare pest risk analyses (PRAs) for eucalypts and other species of Myrtaceae relating to Australia and South Africa.
(v) To develop molecular diagnostic techniques for detection of P.psidii in seed, tissue cultured plants or pollen.

Seedlings of a broad range of commercially important eucalypts and other Myrtaceae species originating from Australia, South Africa, Indonesia and PNG will be tested in Brazil for susceptibility to P.psidii.

The areas of the world where plantations and native vegetation are at risk from P.psidii will be assessed using climate/disease hazard mapping methods recently developed through another ACIAR project. This will be done initially for Central and South America and subsequently South Africa, Australia and other parts of the world.

DNA will be extracted from a range of infected plant material and fungal tissue and transported to Australia for the further development of diagnostic methods to rapidly detect the presence of the rust in germplasm.

Outcomes for this project are currently being prepared