Handbook Part 2 - International Mycological Association

S40IS2 - 0796
Biosecurity: latest developments in systems and tools for fungal identification and disease diagnostics
M.E. Palm
USDA/APHIS, Beltsville, MD, United States
Early detection, accurate identification and rapid response are key components of an effective plant disease
management system for agricultural biosecurity. The detection and accurate identification of a fungal pathogen
rely on a strong base of systematic knowledge and the resulting identification tools. Tools include access to published
and interactive web-based keys, distance diagnostics capabilities, and an array of molecular and biochemical tests.
An effective system also relies on a network of people that include early detectors, trained diagnosticians, and
specialized mycologists. The U.S. utilizes a network of personnel for detection and identification of exotic pathogens
at its borders. More recently a biosecurity network has been established to identify pathogens within the US. This
network utilizes state departments of agriculture and diagnosticians from land-grant universities, which form the
National Plant Diagnostic Network (NPDN), in conjunction with scientists in federal laboratories. In both networks
distance diagnostics can be useful to make a preliminary and sometimes a final identification, if the fungus is
particularly distinctive. In most cases morphological tools are used for a final identification. Increasingly molecular
and biochemical tests are being developed and utilized for targeted pathogens and many of these are being
adapted for rapid determinations in the field. For some groups of fungal pathogens, such as some ascomycetes and
ascomycetous anamorphs, the knowledge base on which to make an accurate identification is lacking. For some
groups of fungi an adequate knowledge base exists but rapid access to that information is lacking. Many fungal
species have yet to be discovered and thus it is not surprising that a number of recently emerging pathogens must be
studied and described as new species. Because these species were not known previously it is impossible to predict
their origin and potential damaging effects. Support for systematics is essential to provide the basis for developing
tools and tests for accurate identification of fungi.
S40IS3 - 0961
A major exotic disease outbreak, emergency response and eradication: banana black Sigatoka, Tully,
Australia, 2001.
PJL Whittle
Department of Primary Industries and Fisheries, Brisbane, Queensland, Australia
Australia’s geographical isolation has assisted its plant industries to remain free of many serious pests and diseases.
Strong quarantine measures have been used to support this status. In the past decade, this approach has evolved
substantially towards a cohesive national biosecurity system that supports international phytosanitary standards,
structured around the shared responsibilities of governments and industries. A good example of the functioning of this
system is provided by the response to an incursion of black Sigatoka (Mycosphaerella fijiensis Morelet) in Tully in April
2001. The ‘hothouse’ of this response provided many lessons for the continued development of Australia’s plant
biosecurity system.
Freedom from black Sigatoka is a benefit the Australian banana industry values greatly. Fungicide and labour inputs
are far lower than would be required if this disease was present. The industry, producing 300 000T per year worth over
$300 million, is based primarily in tropical far north Queensland. Black Sigatoka is endemic nearby in the Torres Strait
and Papua New Guinea. Since 1981, as part of a specific black Sigatoka biosecurity program, nine outbreaks were
detected and eradicated on Cape York Peninsula in remote areas and in one case in an isolated commercial
plantation. Detection of black Sigatoka in Tully, the heart of the 9 000 ha industry, came as a great shock. Industry’s
concern about the expected yield losses and control costs was exacerbated by strict market access restrictions that
were placed immediately on fruit from a 50 km radius around infected areas. An emergency response was mounted,
based on an incursion management plan and the national system for managing exotic pest incursions. Initially,
infected fields were destroyed, with voluntary compensation paid by the industry. As this became unaffordable, the
approach changed to a zero-disease standard to be achieved by removal of diseased leaf tissue, a compulsory areawide
fungicide program and intensive surveillance. Over 13 000 feral and unmanaged residential plants were killed.
Industry and community participation was exceptional, although regulatory enforcement was available when
required. A PCR-based molecular diagnostic assay was developed and was of great assistance. Disease was found
in 25 sites in over 8 900 diagnostic samples. Efforts were assisted by the occurrence of two dry years. Eradication was
completed in May 2002. Area freedom surveillance was conducted, with over 6 300 samples examined leading to a
declaration of pest freedom in March 2005. Full market access was restored and early warning surveillance resumed.
This paper will use the response to black Sigatoka in Tully and other examples to illustrate the functioning of the
emergency plant pest response system in Australia.
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