Models for border inspection for pelleted seeds: How much assurance?

Project ID: 180601
Project Name: Models for border inspection for pelleted seeds: How much assurance?
CEBRA Project Leader: Professor Andrew Robinson
DA Project Sponsor: Peter Thomson, Plant & Pathways Directorate, Regulation & Assurance Branch
DA Division: Biosecurity Plant
DA Project Leaders:

  • Rose Souza Richards, Senior Advisor, Plant Germphlasm Imports (team), Plant Imports group, Plant & Pathways Directorate, Regulation & Assurance Branch


  • Tony Arthur (ABARES)
  • David Dall (DAWR)

Consultation (internal/external):

  • Professor Mark Ducey (University of New Hampshire)

New Zealand has a highly valued and internationally respected seed growing and seed export industry due to its disease-free status and the ability to provide additional growing seasons for Northern Hemisphere producers. The success of the industry is dependent on the ability to import seed of a wide variety of species and from different production areas.

To meet current phytosanitary requirements, MPI has established processes and procedures for the documentation, sampling and testing of imported pelleted seeds for sowing to ensure that foreign seeds as contaminants are not incidentally present in consignments. The current sampling requirement to detect foreign seeds as contaminants requires a sample of 31,540 seeds per lot in order to achieve 95% confidence of detecting foreign seeds in lots that are contaminated at 0.01%. Samples are then analysed for identification of all seeds present in the sample by a seed analyst. Prior to being analysed, the seeds are required to have their pellet removed by soaking under hot water. These measures were implemented after the incursion of velvet leaf in pelleted seeds in 2016, therefore records of contaminants from pelleted seed lots are available.

The same intensity of inspection is carried out for each consignment within the pathway (a pathway is considered as a sequence of consignments of a specified product arriving from a specified supplier) regardless of the source, the processing history, the inspection history of the pathway, country of origin and so on. This inspection regime treats all consignments as equally risky, ignoring potentially valuable information, such as inspection history and pathway assurance measures through audits at the production site.

An alternative testing protocol is required to maximise the sustainability and growth of the New Zealand seed export industry, while minimising the biosecurity risks to New Zealand. Earlier CEBRA work that was designed to answer a similar question for importing small lots of seed (CEBRA 1606A) was hampered by a lack of information about the failure rates of laboratory-based seed tests. This project will involve the analysis of data from a pathway that is subjected to stringent on-shore testing by MPI, namely pelleted seeds.

The purpose of this project is to assess whether (i) using the available data differently, or (ii) using other kinds of data, in combination with some level of on-arrival inspection, will provide assurance comparable to that provided by the inspections that are prescribed by ISPM 31.

This project will assess protocols that deviate from the current specifications (e.g. 95% confidence to detect contaminated seed lots with prevalence 0.01% or greater) on a lot-by-lot basis, yet may provide sufficient assurance that risks are minimised within a pathway. The protocol need to be flexible enough to help facilitate the frequent import of different volumes of seeds, different species of seeds and seeds from different country of origin. Such protocols will be applicable to seed lots and may also be applicable to other commodities that require intervention. The new protocols will allow for the inclusion of other types of assurance, such as auditing in production sites.

Final Report 180601

Research program

Strengthening Surveillance

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