Draft National Potato Wart Response Plan (second consultation)

On this page

• Overview
• Introduction
• Scope
• Definitions
• Classification of restricted fields or land
• Human-mediated pathways for potato wart introduction and spread
• Regulated pests
• Farm biosecurity, phytosanitary measures and restricted field use
  • Phytosanitary measures and restricted field use: Fields with host crop production included in the rotation
    • Index field
    • Adjacent field
    • Primary contact field
    • Secondary contact field
    • Field of concern
  • Phytosanitary measures and restricted field use: Fields with no host crop production included in the rotation
    • Quarantine disposal site
    • Restricted non-agricultural land
    • Restricted agricultural fields no longer in host crop, root crop or plants and plant parts for propagation production
  • Farm-level preventive control plan requirement

Overview

Synchytrium endobioticum is a fungal pathogen and causal agent of potato wart or potato canker disease. It can survive in soil for more than 40 years and no chemical treatments are available to control the fungus. Potato (Solanum tuberosum) is the primary cultivated host. In Canada, it is a regulated and reportable disease and known to be present in Newfoundland and Labrador and Prince Edward Island.

Potato wart is recognized as a regulated pest by the majority of Canada's trading partners, including the United States (where it has been declared eradicated), and by many European countries (where it is present and under official control). Worldwide, spread has largely been controlled through strict quarantine measures, including the prohibition of susceptible host plant production in infected fields and the development and wide-spread use of resistant potato cultivars.

In 2020, the Canadian Food Inspection Agency (CFIA) initiated a full review of its approach to help contain, control and prevent the spread of potato wart based on current science, international standards and new technologies. The review included the development of a pest risk assessment and a pathway risk assessment document, and a review of the investigation procedures and the Potato Wart Domestic Long-Term Management Plan (PWDLTMP). In 2021, the CFIA also implemented a national survey for potato wart based on soil sampling and analysis.

This draft National Potato Wart Response Plan outlines proposed phytosanitary measures to improve the processes used to help contain, control, and prevent the spread of potato wart in Canada (excluding Newfoundland and Labrador). The measures, including the use of resistant varieties, increased soil analysis and the addition of equipment cleanliness requirements, as described in this plan would be applied to fields following the detection and confirmation of potato wart (via symptomatic tubers or detection of S. endobioticum spores) and an investigation procedure to delimit the potential spread. All feedback received will be considered in the finalization of this plan. Once finalized, this response plan will replace the PWDLTMP and an accompanying transition plan will be developed. The transition plan will consider all the steps completed under the current PWDLTMP when confirming the path for lifting phytosanitary measures for fields in Prince Edward Island (PEI) that are currently restricted for potato wart.

Introduction

Synchytrium endobioticum, the causal agent of potato wart disease, is a fungal pathogen that has been reported in Canada, most European countries and many other countries around the world. The pathogen has been declared eradicated in the United States. Dormant potato wart spores can survive extreme environmental conditions in the soil for more than 40 years. To grow, S. endobioticum requires cool, moist conditions during the growing season, particularly in the spring, and generally does not survive in areas with low annual precipitation. Climate suitability modeling suggests that most of Canada's potato-producing regions are a good climatic match for this pathogen and as a result the risk of new introductions establishing in other regions of Canada is high.

In Canada, potato wart is a reportable disease and is present in Newfoundland and Labrador (NL), where it was first reported in 1909, and Prince Edward Island (PEI), where it was first reported in 2000. Potato wart has not been detected in other provinces in Canada as supported by official surveys. In NL, potato wart is regulated under Schedule II of the Plant Protection Regulations and is considered widespread geographically, but at low levels of incidence. In November 2021, the Potato Wart Order (PWO) was issued and established restricted and unrestricted areas within the province of PEI. It also included restrictions on the movement of soil, seed, table and processing potatoes and other regulated things (farm machinery, sod, etc.). Potato wart is present in PEI and with mitigation measures in place, including the Potato Wart Order, is considered to be under official control.

In PEI, potato wart has been managed under plant protection programs since 2000. In 2005, the PWDLTMP was implemented in PEI, and last updated in 2009, to outline the minimum testing and surveillance and risk mitigation activities (phytosanitary measures) required for any parcel of land linked to a potato wart detection. This includes the steps required to undergo a change in a field's potato wart classification and the investigation criteria for fields associated with new detections of potato wart.

The PWDLTMP is a field-based risk management strategy, based on analysis of scientific evidence related to the plant health risk of individual fields. It includes five basic land categories namely, index fields (where the pest has been detected), fields adjacent to the index field (within 15 metres), primary contact fields (related to an index field through movement of soil or seed potatoes), other contact fields (secondary contact) and new or new portions of fields entering potato production for the first time. The latter 2 categories are considered lower risk for exposure to potato wart. Each field category is required to undergo specific steps to verify its freedom from potato wart.

Existing phytosanitary import and domestic requirements to prevent the introduction and spread of the pathogen are outlined in CFIA's automated import reference system (AIRS) and CFIA plant health directives. Canada applies strict import control measures on soil and only allows the import of field grown potato tubers for seed and consumption from the United States to mitigate the risk of entry of S. endobioticum and other regulated pests into Canada.

The primary human-mediated pathways for S. endobioticum are movement of seed potato tubers, movement of soil and soil associated with plant products (including potato tubers for consumption and plants and plant parts for propagation), movement of soil adhering to machinery, implements, and conveyances or movement of contaminated organic solid or liquid waste materials originating from potato processing and packing facilities. Contaminated animal manure is also a risk pathway as the pest can survive the digestive tracts of livestock fed on infested potato culls or other infested organic waste. The pest has a limited ability to spread naturally through the movement of wind-blown soil or waterways. The movement of infected seed potato tubers is the most likely pathway for long distance introduction and establishment of the pest.

In Summer 2022, in support of its program review, the CFIA established an independent panel of international experts and requested they review and assess the situation in PEI and provide a report of expert opinions and recommendations. The report was completed in December 2022 and provided recommendations to the CFIA to improve the management of potato wart disease in PEI, and considerations for the establishment of pest free areas.

Also in 2022, the CFIA established an Industry-Government Technical Working Group focussing on revisions to the PWDLTMP (2009). The objective of this working group was to provide a technical forum to exchange information from key industry stakeholders, to collaborate and to coordinate efforts to obtain input and feedback to improve the current PWDLTMP. The working group provided its recommendations to the CFIA in April 2023.

The international panel report, the recommendations from the Industry-Government Technical Working Group, and the feedback received during public consultations have informed the development of this response plan. Improvements to risk mitigation, including restrictions on seed potato production in restricted fields, increased soil analysis and the additional of equipment cleanliness requirements, are a result of this feedback.

Scope

This National Potato Wart Response Plan (response plan) provides detailed information to the CFIA, potato industry stakeholders, provincial and territorial government stakeholders and other national plant protection organizations on phytosanitary measures to improve processes used to help contain, control, and prevent the spread of potato wart from any regulated areas in Canada, except for NL, while supporting the long-term sustainability of the potato sector in Canada.

When finalized, the response plan will supersede the PWDLTMP, March 9, 2009. An accompanying transition plan will be developed to consider all the steps completed under the current PWDLTMP when confirming the path for lifting phytosanitary measures for fields in PEI currently restricted.

For PEI, the prohibitions and requirements specified in the Potato Wart Order remain in place and are in addition to the risk mitigation measures outlined in this response plan.

Definitions

Definitions of terms used in this document can be found in the International Standard for Phytosanitary Measures 5: Glossary of phytosanitary terms (PDF), and the definitions in the Potato Wart Order, except for the following terms.

Detection

An official CFIA detection of spores of S. endobioticum as determined by morphological identification followed by a molecular method to confirm presence.

Equipment cleanliness

The user must remove all loose adhering soil from all machinery, implements, and conveyances before exiting the field / farm unit as per the requirements of the farm unit's preventive control plan.

Field

A distinct plot of land distinguished from neighbouring plots of land by physical boundaries including a:

• tree line
• fence line
• permanent waterway
• ditch
• road or permanent lane
• berm
• permanent irrigation track
• transition to non-agricultural area (fallow, lawn, wetland)

Freedom from soil

All machinery, implements, and conveyances must be free from soil to the standard of PI-016: Procedure for inspection regulated articles for freedom from soil, plants, plant parts and related matter.

Laboratory bioassay

A method used for the purposes of detecting a pest (such as potato wart) in field-collected soil, using susceptible potato varieties grown under conducive growing conditions with appropriate positive and negative controls to confirm proper environmental conditions for development of the disease.

Pathotypes

S. endobioticum has over 40 pathotypes, defined as groups of isolates with a similar response to a set of differential potato varieties. Pathotypes 2, 6, and 8 have been reported from Canada.

Potato culls

Potatoes that are deemed surplus or otherwise unsuitable for the intended use and are considered waste, including whole or parts of tubers, or tubers with defects related to size, disease, physiology or any other defect.

Preventative Control Plan (PCP)

A written document that demonstrates how risks to plant health are identified and controlled. It includes a combination of control measures that, when taken as a whole, provide for a science-based approach to managing risks posed by hazards, such as plant diseases, and contributes to achieving compliance with phytosanitary measures and regulatory requirements. A PCP can be built off existing farm plans including on-farm biosecurity plans and may also be referred to as a 'systems approach' to mitigate pest risk(s).

"Regulated things"

Means any of the following:

1. S. endobioticum, in all its life stages
2. potato plants (Solanum tuberosum), including tubers or parts thereof
3. soil
4. plants or parts thereof including root crops, nursery stock, greenhouse plants, bedding plants, vegetable transplants and sod
5. machinery, implements and conveyances
6. manure

Restricted field

Field in which S. endobioticum has been found as well as land that by reason of its agricultural history, or its location, is associated with land in which S. endobioticum has been found. Restricted fields are classified as index, adjacent, primary contact, secondary contact or field of concern.

Resistant varieties

Potato varieties which have been accepted by the National Plant Protection Organizations (NPPO) as being considered resistant to infection by specified pathotypes of S. endobioticum, using criteria defined by the NPPO.

Susceptible varieties

Potato varieties which have been accepted by the National Plant Protection Organizations (NPPO) and are considered to be susceptible to infection by specified pathotypes of S. endobioticum, using criteria defined by the NPPO.

Tare soil

Soil that falls from tubers as they move into storage or during the storage and subsequent handling processes. It can accumulate beneath handling equipment at potato storages, processing facilities or other locations where the potatoes are being stored or handled.

Classification of restricted fields or land

Following the detection and confirmation of S. endobioticum (via symptomatic tuber or detection of S. endobioticum spores), the CFIA will immediately place phytosanitary measures on the field and initiate an investigation to identify the possible source(s) of the pathogen. The Agency will also assess the risk relationships between associated fields based on location (adjacent) and past and present human-mediated activities. These relationships are important and determine the risk exposure of associated fields to potential introduction of the pathogen based on the field classification system described below. Details on the investigation and tracing of associated fields are included in Annex A (under development)

During an investigation, the CFIA will delimit the extent of the infestation through soil sampling and analysis of all associated fields. As well, the Agency will implement phytosanitary measures to mitigate risk and facilitate long-term control of the index field or field of concern and all identified associated fields during the investigation. Where possible, the CFIA will expedite the determination of the pest pathotype present.

Human-mediated pathways for potato wart introduction and spread

S. endobioticum spores can spread from one field to another through human-mediated pathways, including:

• movement of infested planting material, such as infected seed potato tubers or soil adhering to non-host plants and plant parts for propagation (nursery stock or sod)
• movement of potato wart contaminated tare soil or soil adhering to machinery, implements and conveyances
• improper disposal of potato packing or processing waste products including wastewater effluent, soil sediment or sludge and organic waste (culls, peels, etc.)
• application of contaminated manure (from livestock fed infected tubers) to fields

Regulated pests

Synchytrium endobioticum, in all its life stages.

Farm biosecurity, phytosanitary measures and restricted field use

The purpose of establishing phytosanitary measures on the index field and all associated fields is to help contain and control the pest and prevent further spread to other fields. These controls and movement restrictions will remain in place until a field has been released from phytosanitary measures, following the land release protocols described in this response plan.

In cases where a field is classified as a field of concern, phytosanitary controls equivalent to those for a primary contact field including freedom from soil requirements and restrictions on potato crop usage will be applied immediately. Intensified soil sampling and analysis (specific methodology based on method of collection of original sample, tare or grid) will be completed and if one or more additional spores is detected the field will be reclassified as "index – viability not confirmed".

To obtain authorization from CFIA inspectors to move their product, and further mitigate against the spread of S. endobioticum spores from a restricted field (including fields of concern), producers must develop and implement a preventive control plan (PCP) for their farm operation. The preventative control plan must incorporate biosecurity measures that include movement of product, machinery, implements, and conveyances, and waste disposal elements and be tailored to meet the needs of each farm.

Phytosanitary measures and restricted field use: Fields with host crop production included in the rotation

Index field

All users of index fields require a preventative control plan as described in the section Farm-level preventive control plan requirement, which incorporates biosecurity, product and equipment movement, and waste disposal elements for their farm operation.

A written authorization is required to move all regulated things from the index field.

Adjacent field

All users of adjacent fields require a preventative control plan as described in the section Farm-level preventive control plan requirement, which incorporates biosecurity, product and equipment movement, and waste disposal elements.

Following the assessment procedures, if S. endobioticum spores have not been detected all phytosanitary measures outlined in the response plan will be removed from the field, except for the prohibition on seed potato production which will remain on the field indefinitely.

The final host crop produced while the field is restricted as an adjacent field must meet the same phytosanitary requirements as the previous 2 crops (processing or tablestock use only, must be sent to a facility with a CA or dry-brushed on farm and sent directly to facility within the province of origin).

Primary contact field

All users of primary contact fields require a PCP as described in the section Farm-level preventive control plan requirement, which incorporates biosecurity, product and equipment movement, and waste disposal elements.

Secondary contact field

All users of secondary contact fields require a preventative control plan as described in the section Farm-level preventive control plan requirement, which incorporates biosecurity, product and equipment movement, and waste disposal elements.

Field of concern

• A field where only one spore is detected and confirmed, via morphology and molecular analysis, will be designated a "field of concern". If a field of concern is not already classified as a primary contact field, equivalent risk mitigation measures will be applied, including the requirement for freedom from soil and restrictions on potato crop usage.
• Intensified soil sampling of the field of concern will be prioritized. The method of soil sampling (tare or grid) will be based on the method of collection of the original sample.
  • If one or more additional spores is detected, the field will be classified as an index field.
  • If the detection threshold (symptomatic tubers and/or 2 spores confirmed via 2 methods) is not met following laboratory analysis of the soil from the intensified sampling the field:
    • will remain under restrictions equivalent to a primary contact field
    • will follow the process from release for phytosanitary measures for primary contact fields described above.

Phytosanitary measures and restricted field use: Fields with no host crop production included in the rotation

Quarantine disposal site

A quarantine disposal site is designated for disposal of soil and liquid and solid waste originating from restricted fields and crops. All machinery, implements and conveyances must be cleaned free from soil and plant debris, and authorized to move by the CFIA prior to exiting these sites. See PI-016: Procedure for inspection regulated articles for freedom from soil, plants, plant parts and related matter for more information.

Quarantine disposal sites will not be considered for release from phytosanitary measures outlined in the response plan until a minimum of 20 years after the last exposure to potato wart waste. Sites will be assessed on a case-by-case basis to determine whether release from phytosanitary measures is possible.

Restricted non-agricultural land

Restricted non-agricultural land is land that is regulated for potato wart but has subsequently been altered, or based on its inherent characteristics, been permanently removed from agricultural use (for example) paved roads, recreational areas or commercial and residential development).

Releasing non-agricultural related land from the response plan's phytosanitary measures

The landowner or land user must apply to the CFIA to have the restricted non-agricultural land considered for release from phytosanitary measures outlined in the response plan. Soil cannot be removed from the site without written permission and freedom from soil requirements may be applied to equipment leaving the site.

This land will be assessed on a case-by-case basis to determine whether release from phytosanitary measures is possible and to ensure the process of converting the land to other uses is completed in a way that does not pose a risk of pest spread.

The CFIA must have confirmation that the field has been permanently removed from agricultural production.

Restricted agricultural fields no longer in host crop, root crop or plants and plant parts for propagation production

Index fields no longer in host crop, root crop or plants and plant parts for propagation production (except botanical seed) may be assessed for partial release from phytosanitary measures outlined in the response plan at the written request of the landowner or land user following a minimum of 50 years of documented non-host crop production.

Adjacent and primary contact fields removed from use for host crop, root crop or plants and plant parts for propagation (except botanical seed) production can be considered for partial release from phytosanitary measures outlined in the response plan at the written request of the landowner or land user. The assessment for full release from phytosanitary measures will not be considered until 50 years after the date of classification.

Secondary contact fields no longer in host crop, root crop or plants and plant parts for propagation (except botanical seed) production may be assessed for case-by-case release from phytosanitary measures outlined in the plan at the written request of the landowner or land user.

Partial release of adjacent and primary contact fields no longer in host crop production

Adjacent and primary contact fields no longer in host crop, root crop or plants and plant parts for propagation (except botanical seed) production may be assessed for partial release from phytosanitary measures at the written request of the landowner or land user.

Fields will be assessed on a case-by-case basis to determine whether release from phytosanitary measures outlined in the response plan is possible (including the risk of natural spread of potato wart into adjacent fields).

These fields may be assessed using soil sampling followed by:

• laboratory analysis for S. endobioticum spores
• laboratory bioassay

If potato wart is not detected, then phytosanitary measures on the field may be amended to:

• remove the requirement for freedom from soil
  • All machinery, implements, and conveyances must meet the equipment cleanliness definition for soil prior to exiting the field as per the procedures described in the grower's preventative control plan.
• host crop, root crop and plants and plant parts for propagation (except botanical seed) production is not permitted until the field has been out of host crop production for a minimum of 50 years
• A PCP is still required until the field is released from all restrictions.

Release of secondary contact fields no longer in host crop production

Secondary contact fields no longer in host crop, root crop or plants and plant parts for propagation (except botanical seed) production may be assessed for release from phytosanitary measures at the written request of the landowner or land user.

Fields that have not produced host crops for a minimum of 25 years may be assessed on a case-by-case basis to determine whether release from phytosanitary measures outlined in the response plan is possible.

These fields may be assessed using the following procedure:

• Soil sampling followed by laboratory analysis for S. endobioticum spores.

Following the assessment procedures, if S. endobioticum has not been detected all phytosanitary measures outlined in the response plan will be removed from the field.

Farm-level preventive control plan requirement

The standard for farm-level preventive control plans (PCP) will be based on the principles included in the National Farm-Level Biosecurity Standard for Potato Growers. The standard will be subject to potato sector review before it is finalized and preventative control plans will be tailored to address the needs of each farm unit. (Note: additional guidance is under development).

• The PCP must detail farm-level risk reduction (biosecurity) practices implemented to help contain, control and prevent the risk of spread of potato wart from restricted fields that are part of their farm operation and the records maintained to document these practices.
• PCPs must include procedures for informing CFIA of critical information including changes in ownership or land users and yearly cropping information.
• Traceability is another important component of a PCP including records related to host crop production (source of seed potatoes, shipment details) and equipment movement.
• An implemented plan will facilitate the issuance of a written authorization to permit the movement of regulated things, including machinery, implements, conveyances and potatoes.