Wollemia nobilis (Wollemi Pine) - Biosecurity New Zealand

It is possible that a serious infection of a Botryosphaeria species could kill the host and
effectively prevent the host and the associated disease from establishing in New Zealand.
This would only be the case for the most pathogenic species of Botryosphaeria found on
Wollemia nobilis nursery stock. It is unlikely that a Botryosphaeria infection would become
necrotic in the host and therefore not be able to spread from the host into the New Zealand
environment, as species of Botryosphaeria can act as an endophyte. The only remaining
option for avoiding exposure is if the host plants are not moved into the New Zealand
environment. As the intention of any importer would be to plant the imported Wollemia
nobilis nursery stock into the New Zealand environment, this final limitation to exposure is
removed.
11.2.4 Establishment Assessment
As indicated in the exposure assessment, the intention of any importer would be to plant the
imported Wollemia nobilis nursery stock into the New Zealand environment, therefore
allowing any Botryosphaeria infection to establish a viable population.
11.2.5 Conclusion of Exposure and Establishment Assessment
Given that the imported and contaminated Wollemia nobilis plants themselves can act as the
agent for exposure and establishment, and the intention of any importer would be to plant the
imported Wollemia nobilis nursery stock into the New Zealand environment, the likelihood of
exposure and establishment is very high and therefore non-negligible.
11.2.6 Consequence Assessment
In the context of the pathway for importing nursery stock contaminated with Botryosphaeria
sp., any potential consequences to people, the New Zealand environment, and the
New Zealand economy will only become apparent after establishment and some degree of
spread.
Potential for spread
Botryosphaeria species can produce abundant conidia on the surface of infected stems or
fruits. The majority of the ascospores and conidia are dispersed by air and rainwater,
respectively. Usually, spore discharge occurs just after periods of surface wetness.
Waterborne ascospores and conidia may be present in rainwater run-off from diseased and
pruned limbs. The transmission of Botryosphaeria within and among adjacent plants may
occur through stem run-off, raindrop splashing and pruning equipment. Similarly, the longdistance
transmission of this fungus may occur through air, pruning equipment, insects and
birds. Species of Botryosphaeria are considered in many cases to have a wide potential host
range, making potential hosts widely available. A species of Botryosphaeria introduced into
the New Zealand environment from Wollemia nobilis nursery stock would be expected to
spread relatively rapidly over its maximum potential range.
Import Risk Analysis: Wollemia nobilis (Wollemi Pine) Araucariaceae Nursery Stock from Australia 14 March 2008 Page 107 of 193