The Canadian Food Inspection Agency (CFIA) has developed procedures for investigating and tracing associated fields following a confirmed potato wart (Synchytrium endobioticum) detection. Information will be gathered from various sources, including the CFIA's databases, grower records, grower interviews and site inspections.
On this page
- Preliminary investigation
- Notification and landowner (and/or land users) interview
- Regulatory control actions
- More information
Preliminary investigation
Upon CFIA confirmation of a potato wart detection, a traceback investigation covering the past 10 years will be initiated. The ten-year time frame may be expanded if specific risks of spread are identified, such as through seed potato movement. The following information will be gathered from available sources to determine potential sources of inoculum and natural spread pathways:
- location based information: Such as topography, relative position to other fields, irrigation sources, proximity to waterways, and land use history whenever records are available
- type of farm operation: Seed potato, tablestock, processing, or non-host crops
- connections to previous potato wart detections or investigations: Relationship to any potato wart restricted fields including those under CFIA regulatory notices or identified in ongoing potato wart related investigations.
Notification and landowner (and/or land users) interview
The landowner and land user will be notified as soon as possible following the confirmation of a new potato wart detection. Notification may be verbal or written and will include information on regulatory notices, land use restrictions, compensation, the National Potato Wart Response Plan (response plan) and the Potato Wart Order.
Following notification, the CFIA will gather more information from the landowner and land users (as applicable), including:
- land use history: Including waste disposal, homestead locations, gardens, and cull disposal
- seed potato sources: Origin of seed potatoes used in the field for the past 10 years
- location of harvested potatoes: Storage location of current potato crop and details of any movement
- historical movement of potatoes and soil: Records for any export or domestic potato shipments from the field in the last 10 years and records on movement and disposition of soil
- crop rotation history: Details of crops grown in the field over the past 10 years
- history of resource sharing: Verify information on shared equipment or storage and location of storage sheds
- planting and harvesting order: For the field for the past 10 years
- farm unit field information: Details of all fields used by the grower(s) in the past 10 years.
Regulatory control actions
Land categorization
Fields associated with the new index field will be categorized as adjacent, primary contact and secondary contact fields based on connections to the new index field and the criteria specified in the response plan. Parent fields that supplied the seed potatoes used in the index field will also be identified.
Index field
A field where two or more spores of S. endobioticum or symptomatic tuber(s) have been detected and confirmed by the CFIA.
Adjacent field
A field directly bordering an index field and not separated from the index field by a physical barrier of more than 15 meters in width, such as a tree line, fence line, permanent waterway, ditch, road or permanent lane, berm or permanent irrigation track and where, during investigation soil sample analysis, no S. endobioticum spores were detected.
Primary contact field
A field where, during investigation soil sampling analysis, no S. endobioticum spores are detected but where there may have been exposure to S. endobioticum spores via at least one of the following pathways:
- Direct movement of machinery, equipment, and conveyances after use in an index field without a documented freedom from soil activity as described in an on-farm preventive control plan (PCP) and documented in associated records
- Planting of propagative host material, such as seed potatoes originating from an index field.
- Transfer of tare soil originating from an index field
- Application of potato waste materials, including wastewater effluent, sludge, and solid organic materials, originating from an index field
- Secondary contact fields with connections to multiple potato wart investigations as determined following case-by-case evaluations, or
- A former "index – viability not confirmed" field where neither symptomatic tubers nor plant parts were detected.
Secondary contact field
A field exposed to an index field through indirect movement (after initial movement to a primary contact field) of common machinery, equipment and conveyances without a freedom from soil activity as described in an on-farm preventive control plan and documented in associated records. During investigation soil sample analysis, no potato wart spores were detected.
Regulatory notices
Regulatory notices are issued for index, adjacent, and primary contact fields, as per the Plant Protection Act and its regulations and the required risk mitigation measures. These may include:
- Notice of Requirement to Treat or Process
- Notice of Prohibition of Movement
- Notice Prohibiting/Restricting the Use of a Place
- Notice of prohibition or restriction of an activity
- Notice of quarantine
- Notice to Dispose – Plant Protection
This list of notices is not exhaustive. Other notices may be issued as required. Notices for index fields will be issued immediately, while notices for other categories will be issued as soon as the associated fields are identified.
Land-owners and/or users of secondary contact fields will be notified of their connection to an index field investigation and the restrictions identified in the response plan will apply. In Prince Edward Island (PEI), the Potato Wart Order specifies the specific regulated things that require written authorization prior to movement therefore requiring no further regulatory notices. Should potato wart be detected outside of PEI, the CFIA will determine if additional notices are required to support further risk mitigation.
Investigative soil sampling
Soil sampling will be conducted in fields categorized as adjacent, primary contact and secondary contact fields at a sampling rate of approximately 5 x 2000 cc. samples per hectare. Soil sampling of additional fields (for example, parent fields) will be determined based on phytosanitary risk factors.
Parent field assessment
Following a new detection of potato wart in a field, investigation soil sampling and testing typically includes parent fields unless they are in recognized potato wart free areas (for example, Canadian provinces or American states recognized as pest free). If the new index field is associated with a previous detection, only the last parent field will be sampled. If the new index field is not associated with a prior detection, parent fields that supplied seed for the previous 10 years will be sampled.
Landowners and/or land users of parent fields that are identified for sampling will be notified that fields have been connected to a potato wart detection and will be soil sampled as part of the ongoing investigation. If regulatory notices are issued to prevent movement of seed potatoes while testing is ongoing, the notice will be removed following a "not detected" result from the CFIA's laboratory. If potato wart is detected, the field would become a new index field and a new investigation initiated.
Pathotyping
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. The CFIA will prioritize the determination of the pest pathotype present in fields with no known linkages to previous detections of potato wart where the pathotype has been confirmed.