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How biosecure are we? Case studies with unwanted forestry pathogens and pests.

A further look at New Zealand’s import health standards.
I. A. Hood, December 2018.

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Executive summary

The problem

In 2016 Scion reviewed national import health standards from the perspective of the forest industry onbehalf of the Forest Owners’ Association (FOA). Import health standards are documents that set out the requirements for importing commodities into New Zealand in order to prevent incursions by unwanted pests and disease agents. They are periodically updated by the Ministry for Primary Industries (MPI). All standards were reviewed in order to include pathways that, although not directly related to forestry, might allow unwanted forest organisms to enter the country circuitously. Standards identified as worthy of further consideration comprised those applying to imports of live plants, seed, and wood products such as poles, sleepers, wood chips, sawn wood and wood used as packaging material.

Client initiatives

The FOA wished to pursue this further and requested Scion to undertake a supplementary review by examining the effectiveness of existing import health standards in preventing the entry of a selection of specific pests and pathogens known to cause injury and damage to New Zealand plantation species beyond these shores.

This project

The pathogens selected were Fusarium circinatum (cause of pine pitch canker), Dothistroma septosporum and D. pini (dothistroma needle blight), and Phytophthora pinifolia (daño foliar del pino). The insect pests chosen were Rhyacionia buoliana (European pine shoot moth), Marchalina hellenica (giant pine scale) and Paropsisterna bimaculata (Tasmanian eucalyptus leaf beetle). Each organism was examined in two stages. Firstly, a summary is provided describing the pest or pathogen and the disease or damage it causes under the subheadings distribution, hosts, biology, signs and symptoms, impact and identification. Then the most likely incursion pathways are considered leading to an inspection of the relevant import health standards and the identification of any gaps or limitations that might allow the organism to invade and establish in New Zealand forest plantations.

Key results and their implications for the client

The import health standard specifications were found to be generally adequate, but there were some openings that might allow an undesirable organism to pass through without interception. Specifically:

  1. a laboratory study has shown that the heat treatment prescribed in the wood packaging standard is only partially effective against F. circinatum, unlike the stronger treatment found in more recent standards for other wood products;
  2. wood products of Pinus species from countries known to harbour Fusarium circinatum require certain treatments that do not appear to apply specifically to those of Douglas fir, also a moderately susceptible host of this pathogen.

Two additional factors emerged during this review. Quality assurance of import health standards is greater when based on quantitative data gathered during field surveys and from interception records. Secondly, an import health standard may be well formulated but challenging to implement, even when procedures are stringently maintained. The sampling protocols prescribed in some standards by practical necessity leave open a path on remaining un-sampled material, but at least the odds of a possible incursion are reduced.

Further work

It is recommended that MPI be requested to review of the import health standard Wood Packaging Material from all Countries, particularly in relation to strengthening the heat treatment prescription. MPI might also consider specifying Douglas fir along with Pinus species in the standards Sawn Wood from all Countries and Poles, Piles, Rounds and Sleepers from all Countries, regarding treatments for imports from countries with Fusarium circinatum. Subject to funding, there may be merit in conducting offshore testing of the potential for certain herbaceous plants, currently allowed into New Zealand, to act as carriers of pathogens such as F. circinatum and P. pinifolia, where these plant species are liable to encounter them in their present distribution ranges.


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