Download Approach to blue stain fungi on ISPM 15-certified wood

2012 IFQRG-10-11
Approach to blue stain fungi on ISPM 15-certified wood packaging in
Australia
Christopher Howard
Grains and Forestry Branch, Department of Agriculture, Fisheries and
Forestry, Canberra, Australia.
Leisa Porter
Plant Quarantine Operations, Department of Agriculture, Fisheries and
Forestry, Canberra, Australia.
Vanessa Brake, Jennifer Morrison, Bernd Sunderhauf
Quarantine and Export Operations, Department of Agriculture, Fisheries
and Forestry, Brisbane, Australia.
Abstract
Actioning of ISPM 15-certified wood packaging that presented with active blue stain fungi
was ceased by the Department of Agriculture, Fisheries and Forestry in June 2012. This was
because only a small proportion of wood packaging was being inspected, blue stain fungi
may be present in wood packaging without blue stain symptoms and the quarantine pest
status of blue stain fungi entering Australia is not known. Based on discussions with experts
on blue stain fungi at IFQRG9 in Canberra, Australia, there is little evidence to support a
pathway for exotic blue stain fungi species to move or be transferred off ISPM 15-treated
wood packaging and establish in the environment.
Background
Blue staining of wood is commonly caused by fungal infection of the sapwood of trees
following wounding by bark beetle vectors (Jacobs & Wingfield 2001; Schmidt 2006). While
staining does not affect the integrity of the timber, the commercial value of the timber is
reduced due to the discolouration. Blue stain fungi have been commonly described in the
genera Ceratocystis, Ophiostoma and Leptographium. Most blue stain fungi do not cause
disease in their hosts but some species within these genera are important plant pathogens and
have caused widespread damage in forests and natural ecosystems and amenity settings. For
example, since the introduction of the causal agent of Dutch elm disease, O. ulmi, to the USA
in 1930, approximately 56% of the forest and amenity trees were killed or destroyed in a 46
year period (Huntley 1982; Hubbes 1999). In addition, following a second outbreak of Dutch
elm disease in the UK in the 1960s caused by O. novo-ulmi, approximately two thirds of the
UK elm population was lost within a decade (Brasier 1996).
Several species within these genera have been associated with blue staining in Australian
hardwood species and some exotic softwood species that are used in the Australian forestry
industry (Aghayeva et al. 2004; Heath et al. 2009; Roux & Wingfield 2009; Romon et al.
2007; Zhou et al. 2004). However, the knowledge of the species of blue stain fungi currently
present in Australia is limited. Some targeted studies in Australia using artificial wounding to
simulate thinning operations and surveys of wounds created by birds, wood-boring insects or
harvesting operations have obtained new records of blue stain fungi-related organisms from
hardwood plantations and natural forests (Kile et al. 1996; van Wyk et al. 2007; Kamgan
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2012 IFQRG-10-11
Nkuekam et al. 2011a; Kamgan Nkuekam et al. 2011b). Currently, rapid identification of
blue stain fungi species is difficult due to the time required to isolate and culture the fungi
and the high-level of morphological taxonomic skills required to make the identification.
Molecular-based approaches to species identification of active blue stain fungi exist
(Khadempour et al. 2010; Roe et al. 2010), but these promising methods still rely on a time
consuming isolation and culture phase.
Biosecurity concerns in Australia
In Australia, the main biosecurity concern with blue stain fungi has been with wood
packaging (Zahid et al. 2008). The United Nations Food and Agriculture Organization
develops the International Standards for Phytosanitary Measures (ISPM) to facilitate
international trade and address quarantine risk. The standard for ‘Regulation of Wood
Packaging Material in International Trade’, ISPM 15, specifies methyl bromide fumigation or
heat treatment to address the risk of insect pests and pine wilt nematode in wood packaging at
the time of manufacture. The ISPM 15 treatments were not developed to address fungal risks.
Some fungi, including those related to species that cause blue staining, can survive the ISPM
15 heat treatment (Ramsfield et al. 2010). In fact, the currently accepted ISPM 15 heat
treatment (minimum core temperature of 56o for 30 min) produces conditions in the timber
conducive to the growth and survival of blue stain fungi (Lambertz & Welling 2010). These
studies suggest that blue stain fungi are often present in wood and develop under suitable
conditions of temperature and moisture while the wood packaging is in service.
Up to June 2012, Australia actioned ISPM 15-certified wood packaging found during
inspection with active blue stain fungi, due to quarantine concerns over exotic blue stain
fungi. However, only about 5% of wood packaging was being inspected, with the remainder
being cleared on documents.
Review of quarantine status of blue stain fungi in Australia
The quarantine risk of blue stain fungi on ISPM treated wood packaging was discussed at the
IFQRG Meeting in Canberra in 2011. It was noted that blue stain fungal taxa tended to be
saprotrophic and widespread internationally. There was also agreement that blue stain fungi
could only be transferred to other timber if beetles were present, as sticky spores prevent
aerial dispersal and their dispersal via water is limited.
It is not known whether the active blue stain fungi that were being actioned on ISPM 15certified wood packaging are already present in Australia. In order to determine the
quarantine risk, baseline data is required on the blue stain fungi present on ISPM 15-certified
wood packaging entering Australia. In addition, comprehensive information on the blue stain
fungi present in both native and plantation timber ecosystems in Australia is needed to
understand what species are exotic and present a quarantine risk.
As discussed at IFQRG9 in 2011, it is uncertain if there is a pathway for exotic species of
blue stain fungi to move or be transferred off the ISPM 15 wood packaging and establish in
the environment. As ISPM 15 treatments are designed to kill insects, it is unlikely that the
exotic bark beetles vectors of blue stain fungi would be present on wood packaging after an
ISPM 15 treatment. However, Australia does have native species of bark beetle (Neumann
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2012 IFQRG-10-11
1979) that are associated with blue stain fungi-related organisms in Australia (van Wyk et al.
2007; Kamgan Nkuekam et al. 2011a). As some insect vectors are attracted to the volatiles
produced by relatives of blue stain fungi (Kile 1993), it is not known whether Australian
native or established exotic bark beetles could be attracted to the volatiles produced by active
blue stain fungi on wood packaging.
Recently, work commenced on identifying the species of blue stain fungi present on ISPM
15-certified wood packaging entering Australia. A diagnostic workshop on the
Ophiostomatoid fungi was held for Department of Agriculture, Fisheries and Forestry
Biosecurity officers in Brisbane, Australia, in October 2011. Twenty three isolates of blue
stain fungi from imported wood, including 20 from wood packing, were identified using two
sets of PCR sequencing primers. All isolates were identified as Ophiostoma species and
included tentative identifications of Ophiostoma piceae, O. floccosum, O. quercus and O.
piliferum. This workshop was a good beginning, but a concerted national approach is
required before the risks, or otherwise, to Australia from exotic blue stain fungi can be
determined.
New policy for active blue stain fungi on ISPM 15-certified wood packaging
Actioning of ISPM 15-certified wood packaging that presented with active blue stain fungi
was ceased by the Department of Agriculture, Fisheries and Forestry in June 2012. This was
because only a small proportion of wood packaging was being inspected, blue stain fungi
may be present in wood packaging without blue stain symptoms, the quarantine pest status of
blue stain fungi entering Australia is not known and uncertainty surrounds whether there is a
pathway for exotic blue stain fungi species to move or be transferred off ISPM 15-treated
wood packaging and establish in the environment. As a World Trade Organisation member,
Australia is obliged to produce a technical justification for any measure for wood packaging
in addition to those in ISPM 15. Until then, the actioning of ISPM 15-certified wood
packaging based on the presence of active blue stain fungi has ceased.
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