RMD 23-04: Biosecurity control programs: Options for mitigating the risk of Synchytrium endobioticum (potato wart) spread

This page was part of the public consultation Support the development of a new national potato wart response plan, which closed on January 31st 2024.

Preface

As described by the International Plant Protection Convention (IPPC), Pest Risk Analysis (PRA) includes 3 stages: initiation, pest risk assessment and pest risk management. Initiating the PRA process involves identifying pests and pathways of concern and defining the PRA area. Pest risk assessment provides the scientific basis for the overall management of risk. Pest risk management is the process of identifying and evaluating potential mitigation measures that may be applied to reduce the identified pest risk to acceptable levels and selecting appropriate measures.

This Risk Management Document (RMD) records the pest risk management process for the identified issue. It is consistent with the principles, terminology and guidelines provided in the IPPC standards for PRA.

On this page

Executive summary

Synchytrium endobioticum is a fungal pathogen and causal agent of potato wart (PW) or potato canker disease. Potato (Solanum tuberosum) is the only known cultivated host. This quarantine pest originated in South America and has been reported in Newfoundland and Labrador (NL) and Prince Edward Island (PEI) in Canada and most of Europe, as well as many other countries around the world.

In Canada, it is a quarantine pest and known to be present and cause damage to potatoes in NL since it was first reported there in 1909, and PEI, where it was first reported in 2000. In NL, PW is regulated under Schedule II of the Plant Protection Regulations and is considered widespread geographically, but at low levels of incidence. The Potato Wart Order (PWO) was implemented in November 2021 which regulated the province of PEI for PW. The PWO also defines a restricted area within the province and restricts the movement of potatoes and other regulated things (such as farm equipment, soil, sod, etc.). As of October 2023, PW was detected in 37 fields in PEI.

Since 2000, PW in PEI has been managed through regulatory programs. In 2005, the Potato Wart Domestic Long Term Management Plan (PWDLTMP) was implemented (updated in 2009) to provide the minimum sampling, testing and surveillance activities required for regulated parcels of land and the criteria for regulating new detections. The PWDLTMP follows a risk based field system and categorizes fields into Categories A (index), B (adjacent), C (primary contact) and D (other contact) and imposes varying levels of restrictions based on risk. The PWDLTMP was put in place to help contain, control and prevent the spread of PW within and out of PEI. The field categories, as defined in the PWDLTMP, form the restricted area as referenced in the PWO, which in part restricts the movement of regulated things from restricted areas in PEI.

Following the detections of PW in export soil samples collected in PEI in 2020, the Canadian Food Inspection Agency (CFIA) undertook a full program review, including an update of its PRA, pathway risk assessment, investigation procedures and the implementation of the National Potato Wart Survey to modernize Canada's approach to managing PW based on current science, international standards and new technologies.

This RMD outlines options for the implementation of biosecurity control measures as a means to effectively help contain, control and prevent further spread of PW.

The current program was analyzed and 2 proposed alternatives were reviewed:

  1. farm-based management system
  2. containment zone (contiguous area)

The CFIA's current proposed approach to address the identified risks is the Implementation of a Preventive Control Plan (PCP) farm-based biosecurity system.

Purpose

The purpose of this RMD is to assess and review options for creating a biosecurity control program where phytosanitary measures could be applied in and surrounding restricted fields to prevent the spread of PW. The final outcome of this RMD is to support the development of a new national-level potato wart response plan to replace the existing PWDLTMP.

Scope

This RMD pertains to the CFIA's management program for PW in Canada. It outlines PW risk mitigation options to help contain, control and prevent the spread of PW under a new national-level potato wart response plan.

Definitions

Definitions of terms used in this document can be found in the Plant Health Glossary of Terms, Potato Wart Domestic Long-Term Management Plan and Potato Wart Order.

Additionally, for the purpose of this risk management document, the following terms are defined as follows:

Area
An officially defined country, part of a country or all or parts of several countries.
Containment zone
A restricted area which a National Plant Protection Organization (NPPO) has determined to be the minimum size necessary to prevent spread of PW from a quarantined area.
Field exchange
The sharing, trading, leasing or rental of agricultural fields between the field owner and field users, for the purposes of crop production. This includes the use of a field that is used in a farming operation that is not owned by the operation.
Field
A distinct plot of land distinguished from neighbouring plots of land by physical boundaries. Physical boundaries include a tree line, fence line, permanent waterway, ditch, road or permanent lane, berm, permanent irrigation track, transition to a non-agricultural area (such as fallow, lawn, wetland), and a real property boundary.
Preventive Control Plan (PCP)
A combination of control measures that, when taken as a whole, provide a science-based approach to managing risks posed by hazards (such as plant diseases) and contribute to achieving compliance with regulatory requirements.
Quarantined area
An area within which a quarantine pest is present and is being officially controlled.
Resistant varieties
Potato varieties accepted by the NPPO as being considered resistant to infection by specified pathotypes of S. endobioticum, using criteria defined by the NPPO. Note: There are different levels of resistance and many different pathotypes of PW.
Susceptible varieties
Potato varieties that have been reviewed by the NPPO and are considered to be susceptible to infection by specified pathotypes of S. endobioticum, using criteria defined by the NPPO. Note: There are different levels of susceptibility.

Background

Synchytrium endobioticum resting spores are persistent in soil and able to survive extreme environmental conditions in a dormant state for more than 40 years. S. endobioticum requires cool, moist conditions during the growing season, in particular in the spring, and generally does not survive in areas with low annual precipitation. Climate suitability modeling indicates that most of Canada's potato-producing regions are a good climatic match for this pathogen and as a result, the probability of establishment of new introductions in other regions of Canada, is rated high. There are no effective chemical treatments available to control PW and there are currently only a limited number of known PW resistant varieties (Goldrush and Prospect) of commercial importance in the North American context.

Similar to experiences in Europe, PW was introduced into NL at the turn of the 20th century in homestead gardens through the planting of infected potatoes at a time when many families relied on vegetable gardens for survival and North American seed potato certification programs were in their infancy (Hampson 1993Footnote 1, Shepard and Claflin 1975Footnote 2). The spread of the disease throughout NL occurred quickly via human-mediated activities such as the exchange of tubers amongst gardeners, movement of contaminated manure and movement of infested soil (Hampson 1993i). The Potato Wart Disease Quarantine for Newfoundland was put in place in 1912 to prohibit the movement of potatoes, soil, root crops and other materials that may be infested with S. endobioticum resting spores out of the province (Hampson 1993i). NL was the only province that was entirely regulated for this pathogen until the Potato Wart Order (issued on November 21, 2021) was implemented in PEI, to help contain, control and prevent the spread of the pest in PEI and to other areas of Canada.

The origin and time of introduction of PW in PEI is not known, but is likely related to trade in potatoes with NL as the 2 provinces share common pathotypes (pathotypes 6 and 8) and isolates from both provinces appear to be genetically related (Gagnon et al. 2016Footnote 3). Since its detection in PEI in 2000, PW has been managed through phytosanitary measures implemented in restricted fields. While positive detections of PW have occurred in each of PEI's 3 counties, the majority of restricted fields are located in the geographic center of the island where potato production is concentrated. Although the exact pathway of pest introduction into PEI remains unknown, a review of the 2000 and 2002 investigations suggests that PW would have been present in PEI at a localized level for a considerable time prior to its official detection.

In November 2021, the CFIA completed a PRA which included information on the probability of establishment and spread of PW, including a list of potential risk factors that likely have played a role in the fungus' spread within PEI (Table 2). The PRA concluded that the probability of spread of PW by natural means is low, while the highest risk pathways for spreading PW within Canada are all human-mediated, for example, through:

  • the movement of field-grown seed potatoes and soil associated with these tubers;
  • the movement of PW resting spores between fields in tare soil or with the soil adhering to agricultural equipment; and,
  • the application of organic waste materials from potato packing and processing operations or manure (originating from livestock fed infected potato tubers) onto agricultural land.

The PRA also provided a basis to examine the effectiveness of the PWDLTMP and response to PW in PEI.

In 2022, the CFIA established an international advisory panel (IAP) of independent experts with experience and expertise in the biology or regulation of S. endobioticum, with a request to assess and review the situation in PEI and to provide a report of expert opinions and recommendations. The report was completed in December 2022 and provided recommendations to support a different approach to the management of PW in PEI, along with considerations for determining a pest free area(s).

Risk management considerations

The Potato Wart Domestic Long-Term Management Plan (PWDLTMP) - March 5, 2009

The current PWDLTMP is a risk-based regulatory management strategy that identifies 4 basic field categories. Fields identified as Category A (index), Category B (adjacent), Category C (primary contact) and Category D (other contact) present a varying degree of plant health risk based on several risk factors (Figure 1). The degree or extent of restrictions placed on an individual field is related to the level of risk based on its relationship and proximity to the associated Category A field.

Categories A, B and C fields are considered high risk fields in the PWDLTMP and are currently placed under regulatory notice subjecting them to specific quarantine and movement restrictions. The PWDLTMP does not require specific controls on Category D fields; however, the field is soil tested during the initial investigation of the associated Category A field followed by a series of visual post-harvest surveillance activities that are necessary to provide confidence that PW is not present in the field.

Key risk factors are the movement of potato tubers, soil and soil adhering to agricultural equipment used in the Category A and waste management and disposal practices. Other potential risk factors are identified in Table 2.

Figure 1. Description follows
Figure 1: Restricted field categorizations including Index fields (Category A), Adjacent fields (Category B), Primary contact fields (Category C), and Other contact fields (Category D).
Description for photo - Figure 1: Restricted field categorizations

An index field is represented in a box in red. The index field includes a picture of a plant in the top left corner. An arrow starts at this plant in the top left corner and follows a path to a tractor next to an orange box below the index field. The orange box represents primary contact fields where seed potatoes, tare soil, potato waste or equipment moved directly from the index field during the last 10 years.

To the right of the orange box, is a tractor and an arrow that points to a yellow box. The yellow box represents other contact fields where equipment moved after first moving to the primary contact field in orange. On the left side of the index field, there a white box that represents a field that is not regulated as it is more than 15 metres from the index field.

Above the index field are two boxes in blue that represent two adjacent fields that are less than 15 metres from the index field in red.

Source: Report - Recommendations of the International Advisory Panel, December 2022.

According to the risk model in Figure 1, the only risk factor that creates an "other contact field" (Category D) is related to the movement of soil associated with farming equipment. On a number of occasions, PW has been detected in Category D fields but the associated primary contact field (Category C) has not been found positive. This suggests that other risk factors, beyond soil moving on farm equipment, may not be accounted for by the model in Figure 1.

When PW is detected in a field (resting spores or tubers with galls), restrictions are implemented and an investigation is immediately initiated, including trace-back (past 10 years of field use) and trace-forward activities to determine the source of infection, to identify associated fields (Categories B, C and D) and potential movement of PW from the Category A field. During this process, fields are assessed for risk and categorized accordingly. Each field is soil sampled using a grid soil sampling protocol and samples are submitted for laboratory analysis for S. endobioticum resting spores. Visual surveillance is also conducted (post-harvest field inspections and tuber inspections) following the initial soil sampling and analysis when restricted fields are first identified. The primary PW detection method for Category B, C and D fields is through visual surveillance following the harvest of a PW susceptible variety.

Over time, each field must undergo the assessment steps for its field categorization as identified in the PWDLTMP to determine if PW is present in the field. As a field moves through the identified steps in the plan, restrictions are eased and when all steps are complete the field will be free from restrictions under the PWDLTMP. The requirements for each field category are outlined in the PWDLTMP. Key requirements, biosecurity and risk factors in relation to this RMD are summarized below:

Category A (index)
  • Biosecurity controls and freedom from soil requirements remain in place on Category A fields until fully assessed and released from restrictions under the PWDLTMP.
  • The requirements for mandatory use of potato varieties resistant to PW is limited to the Category A field.
Category B (adjacent) and Category C (primary contact
  • Biosecurity controls and freedom from soil requirements are required for Category B and C fields but may be removed through the field assessment criteria identified in the PWDLTMP.
  • Category C fields may have their soil freedom restrictions lifted under the PWDLTMP after a single soil test and visual surveillance following a crop of a susceptible potato variety indicating that PW was not detected. Potato production will be limited to processing and/or table stock with a phytosanitary inspection on table stock. This process carries the potential risk of exposing other fields to PW through farming practices before the field has undergone a comprehensive field assessment for full release.
Category D (other contact)
  • Biosecurity controls such as freedom from soil requirements or waste management are not obligatory for Category D fields because they are presently considered low-risk due to their distant connection with Category A fields.
  • There are no specific regulatory requirements following soil sampling and analysis with not detected results.
  • The current risk model employed in the PWDLTMP fails to consider several critical risk factors including waste management practices, historical land use, management of tare soil and soil associated with equipment. These unaccounted risk factors may have contributed to the localized spread of PW.

CFIA experience in managing soil-borne potato pests in Canada

Potato wart in PEI

Since the initial PEI PW detection in 2000, a number of restricted fields were released from restrictions under the PWDLTMP. However, a portion of these fields, mainly situated in the Kensington area, have returned to their previous restricted status following new PW investigations. The majority of PW detections occurred in potato fields used to produce potatoes for processing located in Queens and Prince counties. The detections in 2012, 2014 and 2020 were associated with fields that produced seed potatoes including the detection in Kings County.

Historically, PW investigations were triggered by the discovery of PW symptomatic tubers during harvest, which is followed by intensive soil sampling and testing on the associated fields which may then result in the detection of additional PW positive fields through soil analysis. The regulatory response required to delimit and contain the investigations initiated between 2020 to 2023 (8 new detections from fall 2020 to spring 2023) significantly increased the overall number and area of the restricted fields across PEI and further support the in-depth program review.

As of May 2023, there are 1,362 restricted fields or 17,306 hectares (42,764 acres) due to PW (Table 1; Figure 2).

Table 1: Number and total size of the potato wart restricted area by field category.

Potato wart restricted area (October 2023)
Field type Number of fields Hectares
Category A (Index) 37 791
Category B (adjacent fields) 51 728
Category C (primary contact fields) 333 3,613
Category D (other contact fields). 941 12,174
Total 1,362 17,306

Source: CFIA investigations 2000 to 2023.

Figure 2. Description follows.
Figure 2: Distribution of PW restricted fields categories on PEI.
Description for photo - Prince Edward Island Potato Wart Index Fields – July 2023

CFIA map of Prince Edward Island (PEI) index fields.

This map of the province of PEI depicts 37 fields in red, known as index fields, where potato wart has been detected.

The index fields are located in various areas on the western side and middle of the island. One field is located on the eastern side of the island.

This map was produced by the Mapping and GIS Service of the Canadian Food Inspection Agency.

The 6 index fields detected between 2021 to 2023 have associations with PW fields dating back to the original 2000 investigation. 3 of these detections occurred in fields considered as low risk – Category D - under the field classification system outlined in the PWDLTMP. This suggests that other risk factors may have influenced the dissemination of resting spores and facilitated fungus spread into these fields. Possible risk factors that may have exposed some fields to PW include historical field use and ownership, disposal of agricultural and processing waste material, the return of tare soil back onto agricultural fields, connections to multiple investigations along with gaps in farm-level best management practices (for example, on-farm biosecurity measures). In addition, the use of field exchange for potato production creates concerns relating to biosecurity, traceability and the ongoing use of farm equipment from different potato growers on the same parcel of land. In total, 11 potato farms have been involved in PW trace-out activities, but they own only 26% of the 1,362 restricted fields. Furthermore, the planting of PW susceptible varieties (for example, Russet Burbank, Shepody, Superior and Atlantic) and increased use of irrigation, both of which increase the conducive conditions necessary for PW spore development, in fields at risk for PW over the last 2 decades may also have been a contributing factor in the recent detections.

In review of the most recent detections in PEI, along with the assessment conducted by the IAP, a number of changes are recommended for consideration during the development of the new national-level potato wart response plan to enhance the regulatory approach to specifically address additional risk factors that may have contributed to the spread of PW in PEI.

Potato cyst nematodes in Canada

Potato Cyst Nematode (PCN) is a soil-borne regulated pest of potato production and the approach taken to prevent its spread in Canada is similar to the measures available to control PW. The CFIA manages 3 PCN regulated areas in Canada, namely, Newfoundland and Labrador (1962), Central Saanich, British Columbia (1965) and Saint-Amable, Quebec (2006).

The phytosanitary risk associated with potato wart is described in CFIA's Plant Health Risk AssessmentFootnote 4 (Request 2021-051):

  • The movement of potatoes, soil and other regulated things with associated soil, such as farm machinery, presents a risk for the spread of PW and this risk means that limiting the movement of these items from restricted areas to other areas is a high priority.
  • Seed potato tubers pose the highest risk of pathogen spread, since the resting spores (either within the tuber or in associated soil) have immediate access to host tissue for invasion. The unintentional planting of an infested seed potato would directly transfer PW to a new location.

Recommendations of the International Advisory Panel on Potato Wart Disease Management on Prince Edwards Island (2022)

The IAP members provided the CFIA with a technical report based on their expert opinion of the PW situation in PEI. The report was completed in December 2022 and provided recommendations to support a different approach to the management of PW in PEI, along with considerations for re-establishment of a pest free area(s).

The report included a significant number of recommendations relevant to this RMD, including:

  • Establishment of 2 biosecurity control areas in PEI to address concerns of potential pathogen spread to other areas.
  • The requirement of freedom from soil (equipment cleaning) for Category C and D fields while they are under additional restrictions.
  • Increased soil testing and analysis for removing restrictions. For example, incorporating the use of resistant varieties and soil sampling to remove restrictions, implementing tare soil testing as a methodology and determining the intensity of soil sampling based on risk (that is, field category, crop end use, or crop destination).

Potato Wart Domestic Long-Term Management Plan Working Group (PWDLTMP WG) Final report (April 2023)

To support the review of the PWDLTMP, the CFIA established a technical working group of provincial and potato industry representatives, including the Governments of PEI and Ontario, Canadian Potato Council and PEI Potato Board. The PWDLTMP WG provided a final report of their recommendations in April 2023.

The report included various recommendations relevant to this RMD, including:

  • The need for enhanced record keeping.
  • To maintain a field based biosecurity system with improvements regarding field categorization based on risk assessment, use of resistant varieties for releasing from specific restrictions, and review of biosecurity for handling regulated potatoes and things.
  • The group was not able to reach a full consensus on freedom from soil (equipment cleaning) requirements. Some working group members did express the need for freedom from soil requirements for all restricted fields, including Category D fields.

Risk factors (activities or occurrences) that contribute to pest entry into a field or spread within a field and farm

The introduction of potato pests and diseases onto a farm occurs through a wide range of pathways. Knowing the pests of concern for a farm and identifying the pathways for introduction, establishment and spread are key considerations of a farm-based biosecurity system. The adoption of a PCP farm-based biosecurity system would significantly enhance biosecurity activities for all fields used by the owner and/ or grower. The common pathways of PW spread are as follows:

Table 2: Risk factors and common spread pathways of potato wart.

Risk factor Level of spread
Human-mediated spread
Movement of infested seed potatoes between fields Spread potential locally and over long distances
Movement of plants for planting with contaminated soil
Movement of contaminated soil on equipment between fields
Movement of contaminated soil on shared/custom equipment between fields
Movement of contaminated tare soil between fields
Movement of contaminated soil with livestock (on hooves)
Movement of contaminated manure (from livestock fed infested culls, peels, potato pulp)
Movement of processing waste – wastewater effluent
Movement of processing waste – tare soil and sludge
Movement of processing waste – organic materials (culls, peels, biogas digestate, potato pulp)
Natural spread
Earthworm activity Spread potential local
Wind-blown contaminated soil particles
Soil erosion from water run-off
Movement of contaminated soil with wild animals (on hooves)
Historic events
Old storage facility site location Known/dependent on the relationship between historical event and potato production
Old vegetable garden site location
Historical land ownerships
Land rental/trading relationships (past and present)
Physical proximity to an infested field

The potential movement of PW resting spores through the movement of tare soil and farm equipment with soil to other fields within a farm is an important consideration for localized spread.

In a PCN study, another soil-borne quarantine pest of potatoes, the authors found the main cause of PCN spread was machinery and tare soil and the most important spread is within the field itself and fields used by the same farmer (M. Goeminne, et al. 2011Footnote 5). The study indicated that the actual number of infestations is higher than the known number of infested potato fields identified through standard screening methods and this could be explained by the fact that small infestations are difficult or practically impossible to detect (M. Goeminne, et al. 2011v).

On a number of occasions in PEI, symptomatic tubers were observed by growers, despite the field being subjected to soil testing and multiple post-harvest tuber inspections prior to PW detection. Multiple susceptible potato crops appear to be required to increase the PW population to a detectable level.

The IAP panel recommended that all machinery should be cleaned to a high standard before leaving restricted fields or control areas and that the CFIA should verify freedom from soil for equipment after the cleaning process (IAP 2022). They also indicated that infestations with very low numbers of resting spores may take many crop cycles with susceptible potato varieties to build up inoculum in the field to a level that might be detected in soil tests or via visual tuber inspections. The IAP considers it likely that other infested fields exist and will be detected in the future (IAP 2022).

Management options

The objective of this RMD is to evaluate and analyze various PW management options by examining the pros and cons of each option. Following the engagement period, the CFIA will review the feedback received and determine the best management option or combination thereof.

Analysis of Current Program: A field-based management system based on the existing PWDLTMP

The PWDLTMP was designed to contain and control PW spread from restricted fields through the immediate implementation of strict phytosanitary measures and targeting key pathways of risk (tare soil, equipment movement, tubers and waste from restricted fields [A, B and C]). It facilitates trade, as the regulatory program is based on international standards, proven risk mitigation activities and is understood by trading partners and referenced in the current U.S. Federal Order. However, PW has been detected in 4 Category B, 14 Category C and 16 Category D fields since 2000. Many of these detections occurred in subsequent years after the initial investigation was complete and following the additional planting of susceptible potato varieties. This suggests that other critical risk factors were not accounted for within the current management plan. In addition, the detections in Category C and D fields suggest a potential risk of exposing PW to other fields through farming practices as these fields can be assessed and released from freedom of soil requirements before the field is fully released from all specific restrictions. The unaccounted risk factors may have contributed to the localized spread of PW which is challenging to detect at low levels due to PW's persistent dormant stage in soil. Repeated detections in restricted fields (B, C and D) and in unrestricted fields where the infection source cannot be identified, have increased uncertainty in the CFIA's ability to help control and contain PW.

With each new detection, the size of the restricted area has increased significantly, negatively impacting industry and increasing the resources required to manage PW. Between 2009 to 2023, the size of the restricted area in PEI more than tripled, from 5,145 hectares (12,713 acres) to 17,306 hectares (42,764 acres). Approximately 75% of the restricted area is not owned by a potato grower and undergoes field exchange. The PWDLTMP was developed to help support the long-term management of individual fields regardless of ownership or management of that field changing over time. However, a lack of awareness of the location and status of restricted fields during field exchange has created biosecurity and logistical challenges for land owners, potato growers, brokers and potato purchasers. These communication challenges and biosecurity gaps related to field exchange may have resulted in PW spread between farms.

Alternative option 1: Farm-based management system

Context

A farm-based system would require growers who use restricted fields (Category A, B, C and D) as part of their annual farm production unit to develop and submit a formal PCP farm-based biosecurity system to the CFIA. The PCP would be designed to limit the potential spread of PW within a farm unit and protect fields from potential PW spread through human-mediated activities. The PCP would also target enhanced product traceability, record keeping, waste stream management and reducing soil movement through human-mediated activities from all restricted fields to unrestricted fields.

The PCP should be based on the National Farm-Level Biosecurity Standard for Potato Growers (CFIA 2012). This standard identifies principles regarding farm property management, farm operational management and plant health management aimed to help prevent and manage the introduction, establishment and spread of pests through the use of best management practices.

Pros

  • The implementation of a mandatory PCP could address concerns related to the movement of soil and waste as a pathway for PW spread from all restricted fields, particularly in cases where the PW is present but remains undetected.
  • A PCP would enhance record keeping by requiring records related to field use for all crops produced, training, waste application and the movement of equipment used during crop production. This would standardize record keeping and traceability and reduce the risk of spread within the farm unit and to unrelated farms.
  • Enhanced record keeping would aid investigations by increasing efficiency and confidence in the process.
  • Supports the creation of pest free places of production (PFPP), pest free area and commodity export certification due to enhanced traceability and reduced risk of spread.
  • A well-designed PCP should help reduce potential exposure from restricted to unrestricted fields within the farm unit.
  • In parts of Canada, many potato farms are dependent on field exchange. A number of PW investigations have been related to fields shared between farms in the 10 year trace back, therefore, the exchange of agricultural fields may be a contributing factor to the spread of PW between farms. A PCP would require the grower to be aware of the field status of all fields in their operation prior to the production of a potato crop and ensure appropriate biosecurity measures are in place when using fields not owned by the grower.
  • Once implemented, a PCP should require fewer CFIA resources than the current program.

Cons

  • Increasing biosecurity through the implementation of a PCP would be a significant undertaking for implicated farms (for example, increased regulatory requirements such as record keeping).
  • The PCP requirement would be applied to restricted fields that are exchanged (rented, leased or shared) for potato production. The new requirements may create a disincentive for growers to use restricted fields or to share/exchange fields with farms with restricted fields. This may create field-use challenges in PEI.
  • Adopting these practices does not guarantee protection from potential PW spread.

Alternative option 2: Containment zone (contiguous area)

Context

In certain scenarios, the implementation of a containment zone to create a contiguous restricted area to more effectively and efficiently manage the risk of PW could be beneficial. Zones would be clearly delineated geographical areas, not based on municipal boundaries, with the objective to help contain PW to an area defined by physical borders such as roadways, waterways or forests.

A containment zone is an alternative option where the traditional approach in managing PW, either by a field-by-field system or farm-based system is no longer efficient or sustainable to contain PW.

This option is particularly relevant in scenarios where PW detections are concentrated in a geographic area with multiple or unknown risk factors contributing to PW spread. In addition, containment in and around the infested restricted area would allow for the application of strict phytosanitary measures to help contain, control and prevent further spread of PW. In doing so, the containment zone helps protects fields outside the zone from exposure to PW and thereby limits the spread of PW.

The ability and time required to achieve eradication would be uncertain if the number of restricted fields within the containment zone is high, and PW has been present for a considerable length of time without effective biosecurity measures in place.

Within the containment zone there may be the potential to establish PFPP in accordance with International Standard for Phytosanitary Measures No. 10 (ISPM 10) when a grower has a sufficient number of fields that are not exposed to PW and the grower intends to maintain the PFPP through implementation of additional phytosanitary measures that meet ISPM 10 requirements. The containment zone would be excluded from any future consideration in the establishment of a pest free area.

Pros

  • The implementation of a containment zone would address concerns in scenarios where PW populations continue to be detected, where multiple risk factors have occurred over time contributing to potential spread and where PW will remain present in a specific geographic area for the foreseeable future (that is, in the central production area in PEI near Kensington).
  • A containment zone would be consistent with the containment approach taken to address PCN in Saint-Amable, Quebec and in Central Saanich, British Columbia.
  • A containment zone could support the future establishment and maintenance of pest free areas, as per ISPM No. 4 "Requirements for the establishment of pest free areas" and ISPM No. 8 "Determination of pest status in an area". The establishment of a pest free area, would support ongoing trade in areas outside the containment zone if new detections of PW occur in the zone.
  • Once implemented, a containment zone may require fewer resources than the current program but similar resources to the Proposed Alternative Option 1. If PW is detected within the zone, an investigation would continue to be required to ensure it is delimited and contained within the geographic boundary of the containment zone.

Cons

  • A containment zone would affect growers inside the zone who may not be connected with any of the PW investigations or have any restricted fields.
  • All growers located within the containment zone would need to develop PFPP or Pest free Production Sites to support movement of regulated things from the contiguous containment zone (for example, anything moving with soil).
  • All equipment would need to be free from soil before leaving the containment zone creating challenges for producers with fields both inside and outside the zone unless they have established a PFPP inside the zone.
  • Any restricted fields outside of the specific containment zone would need to continue to be restricted by either the current program or Proposed Alternative Option 1 and could impact any desire to develop future pest free areas.
  • The exact boundary of a containment zone would require extensive delimitation and surveillance, based on visual surveillance and soil sampling, to define the perimeter of the zone and would be subject to change if detections occur within the buffer zone.

Risk management proposal

The CFIA's review of past investigations, other risk factors, such as management of waste, historical landowners and field exchange and observations of local spread have concluded that changes to the current program are required and a more rigorous biosecurity approach is warranted.

The CFIA's current proposed approach to address the identified risks is Proposed Alternative Option 1: Farm-based management system. This option balances the risk factors of human-mediated spread through the movement of potato tubers, soil (for example, tare soil and soil adhering to agricultural farm equipment), agricultural inputs (for example, manure) and waste streams from a farm using fields restricted due to the risk presented by PW. The approach also safeguards field exchanged between growers using restricted fields and potential exposure to PW. In the future, if detections continue to occur, Proposed Alternative Option 2: Containment Zone (Contiguous Area) may be the most appropriate approach to prevent the spread of PW in situations where detections are high and concentrated in a geographic area and where multiple or unknown risk factors are contributing to spread. In these situations, the persistent presence of PW and unknown duration of the population would warrant more stringent mitigation actions.

Following receipt of comments and feedback from stakeholders, the specific details of the final decision will be defined in the future Potato Wart National Response Plan, replacing the current PWDLTMP.

It should also be noted that the Potato Wart National Response Plan, which will be supported by this RMD, will apply to PW detections in any province, except Newfoundland and Labrador. PEI specific recommendations may stem from the Potato Wart National Response Plan.

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