D-26-01: Bacterial ring rot program for field grown seed potatoes

Effective Date: October 12, 2026 (Original)

On this page

• 1. Legislative authority
• 2. Definitions, abbreviations and acronyms
• 3. Introduction
• 4. Scope
  • 4.1 Regulated pests
  • 4.2 Regulated articles
• 5. Roles and responsibilities
  • 5.1 Grower's duty to provide reasonable assistance
• 6. Legislative requirements to maintain biosecurity and record keeping
  • 6.1 Cleaning, disinfection and best practices
  • 6.2 Growers record keeping requirement
  • 6.3 Storage - Cleaning and disinfection requirements
  • 6.4 Equipment sharing and cleaning requirements
  • 6.5 Storing non-certified potatoes and requirements
• 7. BRR related requirements for established seed potato grower and field grown seed potatoes
  • 7.1 Application requirements
  • 7.2 Documentation requirements for the movement of certified seed potatoes
  • 7.3 Annual testing requirements for field grown seed potato lots and procedures
  • 7.4 BRR testing results
• 8. Investigation procedures
  • 8.1 Initial response when BRR is detected on a seed potato farm unit
  • 8.2 Growers records to support the investigation
  • 8.3 Testing on the farm unit and trace-back investigation
  • 8.4 Sampling rates and testing during an investigation
  • 8.5 Grower notification and outcome of the investigation
• 9. BRR-related requirements for new seed potato growers and farms re-entering the CSPCP
  • 9.1 Cleaning and disinfection requirements
  • 9.2 Management of volunteer potatoes in a field with BRR
  • 9.3 Application process
  • 9.4 BRR testing for new growers
  • 9.5 Enhanced sampling program for growers requesting to re-enter the CSPCP
  • 9.6 Issuance of tags and records of bulk movement during the first 3 years after a BRR detection
  • 9.7 Return to certification
• Appendix 1: Roles and responsibilities
• Appendix 2: BRR monitoring program - Sample size
• Appendix 3: Sampling procedures for seed potato growers
• Appendix 4: Sampling rates during a BRR investigation
• Appendix 5: Flow charts for BRR testing once it has been detected on a seed potato farm unit
• Appendix 6: Summary requirements
• Appendix 7: Enhanced sampling rates

This directive sets out the bacterial ring rot (BRR) requirements for producing field-grown seed potatoes on farm units participating in the Canadian Seed Potato Certification Program (CSPCP).

It outlines:

• mandatory biosecurity measures
• sampling and testing protocols
• requirements for new seed potato farms
• BRR investigation procedures
• farms re-entering the program after a BRR detection

This directive supersedes D-97-12: Seed Potato Certification Program – Bacterial Ring Rot Testing Program for Field Grown Seed Potatoes (5th Revision) and D-95-18: Seed Potato Certification Program - Investigation Procedure after Clavibacter michiganensis Subsp. sepedonicus has been detected on a Seed Potato Farming Unit (4th Revision).

1. Legislative authority

• Access to Information Act
• Seeds Act
• Seeds Regulations
• Plant Protection Act
• Plant Protection Regulations

2. Definitions, abbreviations and acronyms

Definitions for terms used in the present document can be found in the Seeds Regulations, Plant health glossary of terms or as defined in this section:

Crop

means breeder's selection seed potatoes or a variety and class of seed potatoes, growing in an aseptic environment, a protected environment or in one or more fields of a farm unit.

Index farm

means the seed potato farm unit where a regulated pest or disease, such as BRR, has been confirmed.

Lot

means the quantity of harvested seed potatoes of a variety and class that is identifiable by one certificate number or the quantity of breeder's selection seed potatoes that are identifiable by one certificate number.

Non-certified potatoes

means potatoes that do not meet the standards for any of the classes established in Seeds Regulations Part II or seed potatoes that have been transported without required certification documents or have lost their identity.

Seed source (parent) farm unit

means the seed potato farm unit from which seed potato lots originated in the previous year and were supplied for planting.

Sister lot

means the lots of seed potatoes that originated from a common seed source.

Trace-back investigation

means an investigation conducted to identify seed potato source farm units that may have provided seed potato lots to the index farm unit or that may have used common equipment or storage facilities associated with an index farm unit.

Trace-out investigation

means an investigation conducted to identify seed potato farm units that may have received seed potato lots from an index farm or used common equipment or storage.

Volunteer potato tuber

means a potato tuber that has overwintered from a previous crop and subsequently grows into a potato plant in the following growing season, with the potential to develop additional tubers.

3. Introduction

Clavibacter sepedonicus, the causal agent of BRR, is one of the most destructive bacterial pathogens affecting seed potato production. Therefore, BRR is one of the most important pests of potato production and of considerable economic importance due to its potential to reduce yield and quality.

Under the Seeds Regulations Part II, there is zero tolerance for this pest on a seed potato farm unit. A mandatory laboratory testing program is in place to maintain the health status of Canadian seed potato stocks.

BRR can survive in the soil and is persistent on tubers and plants. It survives best under cool, dry conditions and spreads through contamination of storage facilities, vehicles, and containers, as well as infected tubers.

The bacterium survives as a dried biofilm on surfaces for extended periods and can spread via:

• physical contact during planting
• harvesting
• handling

Volunteer potato plants emerging in previously infected fields pose a significant risk of reintroducing the pathogen and compromising non-detected result status. Measures to prevent recurrence and ensure compliance with seed certification standards include:

• rigorous cleaning
• disinfection of all equipment and facilities
• proactive volunteer potato plant management

This directive explains the requirements related to BRR in the Seeds Regulations Part II including the requirements for new seed potato growers and for those seeking to regain access to the program on farm units where BRR has been detected. The requirements described apply to all lots and crops on the farm unit, including those not entered for certification or those rejected from certification.

For effective disease control and potential eradication, follow-up actions are required once there is a detection in seed or non-seed potatoes produced on a seed potato farm unit. Each case must be:

• investigated to contain infected lots
• identify the source of infection
• prevent further spread to other seed potato farms

Investigative actions beyond seed potato farm units participating in the program fall outside the CFIA's legislated mandate and may be carried out by provincial authorities or growers' associations, depending on their respective mandates.

The Seeds Regulations Part II also requires specific BRR testing for nuclear stock class material and its equivalent. The plant health policies regarding these are covered in two other directives:

• D-97-08: "Production, Maintenance, Multiplication, and Certification of Nuclear Stock Seed Potatoes"
• D-97-11: "Seed Potato Certification Program - Requirements for the production of Pre-Elite seed potatoes from sources other than Nuclear Stock"

The requirements for BRR and imported seed potatoes from the United States are contained in CFIA directive D-98-01.

• D-98-01: Import Requirements for Seed Potatoes and Other Potato Propagative Material

4. Scope

This directive is intended for use by:

• CFIA inspection and laboratory staff
• CFIA-approved laboratory
• grower associations
• seed potato growers

It explains:

• roles and responsibilities of growers
• biosecurity measures and testing requirements
• the investigative actions to be followed upon detection

4.1 Regulated pests

Clavibacter sepedonicus, the pathogen causing bacterial ring rot in potatoes.

4.2 Regulated articles

• field-grown seed potatoes (Solanum tuberosum)
• all non-certified potatoes on a seed potato farm unit
• equipment, storage and vehicles used to produce seed potatoes

5. Roles and responsibilities

Roles and responsibilities for the CFIA and seed potato growers are aligned with the Seeds Regulations Part II and are summarized in appendix 1.

5.1 Grower's duty to provide reasonable assistance

Providing reasonable assistance to the CFIA is required for:

• informing the inspector of the status and location of all lots including the location of lots stored elsewhere
• collecting samples
• providing access to all storages including boxes and bins
• providing all records related to the investigation, including records of cleaning and disinfection
• providing records to trace the movement of all potatoes from the farm unit under investigation
• moving all boxes in a storage to provide access to all lots in storage for sampling by the inspector or sampling under the inspector's supervision
• if a lot of potatoes is stored in a bin behind another lot, informing the inspector of the first opportunity when the lot will be accessible and coordinating with the inspector to provide access for sampling by the inspector or sampling under the inspector's supervision.

6. Legislative requirements to maintain biosecurity and record keeping

Information on the biosecurity measures required to maintain seed potato crop certification, with particular emphasis on sanitation practices to prevent the introduction and spread of BRR within farm units. Given the highly infectious nature of BRR and the difficulty of eradicating the pathogen once established, strict biosecurity measures are essential.

The CFIA in collaboration with:

• producer organizations
• provincial governments
• territorial governments
• academia

We have developed:

• national biosecurity standards
• protocols
• strategies

The national biosecurity standard for potato growers is voluntary but recommended and can be found at: National Farm-Level Biosecurity Standard for Potato Growers

6.1 Cleaning, disinfection and best practices

A full cleaning followed by disinfection is an efficient way and best practice to prevent the spread of various pathogens including BRR.

1. Remove all soil and organic debris from:
   • equipment
   • bins
   • surfaces
2. Prior to the reception and use for certified seed potatoes from outside the farm unit, clean and disinfect all:
   • bins
   • storages
   • handling equipment
3. Apply disinfectants that are registered for the control of BRR by the Pesticides Regulatory Directorate or Health Canada and following the manufacturer's instructions on the product label.

6.2 Growers record keeping requirement

To maintain separation between multiple farm units and to demonstrate that proper cleaning and disinfection has occurred, the grower must keep records, like a cleaning and disinfection record, to show that the following have been cleaned and disinfected properly:

• equipment
• vehicles
• storage areas

The record must include the following details:

• identification of the equipment cleaned
• location where disinfection took place
• type of disinfectant used
• rate used
• contact time
• date of disinfection
• name of the person who performed the disinfection

A record is mandatory in the following situations:

• machinery or equipment moving between separate seed potato farm units from the same grower
• machinery or equipment moving between a seed potato farm unit and a commercial farm unit
• loaning or renting potato storages outside the seed potato farm unit
• purchasing, loaning or renting used machinery outside the seed potato farm unit

6.2.1 New seed potato growers and growers re-entering the CSPCP after a BRR detection

New growers entering seed potato production and growers seeking to re-enter the program following a detection on their farm unit will also be required to complete a full cleaning and disinfection then obtain a Disinfection Report (CFIA/ACIA 2415) issued by the CFIA, see section 9.0 for more details.

6.3 Storage - Cleaning and disinfection requirements

To maintain certification integrity of the storage facility and related equipment, the following requirements must be met:

• all vehicles carrying shipments of bulk potatoes must be cleaned and disinfected before loading and be accompanied with a record of bulk movement
• disinfect all machinery, equipment and boxes coming from outside the seed potato farm unit:
  • contract
  • purchase
  • loan
• a seed potato grower with two or more separate farm units must maintain separation between the farm units. Common vehicles and equipment must be cleaned and disinfected between farm units
• two or more seed potato farm units sharing a common equipment without complete records of disinfection of the equipment between farm units or sharing a common storage will be considered as only one farm unit during an investigation

Therefore, if one farm unit is decertified, all other farm units within the group that share equipment or storage facilities will also be decertified

6.4 Equipment sharing and cleaning requirements

Cleaning and disinfection of equipment and machinery must occur before use on a farm unit(s) including:

• rented
• borrowed
• shared
• used equipment entering the farm unit

For example, of equipment associated with but not limited to:

• cutting seed potato tubers
• planting
• tilling
• spraying
• harvesting
• storage
• shipping

As a best practice, growers should prioritize the use of equipment dedicated solely to seed potato production to minimize the risk of disease transmission and maintain seed quality standards.

New equipment, boxes and storage facilities that have never been used prior to arriving on the farm unit need to be recorded in the disinfection records as "new" but do not need to be disinfected when they first enter the farm unit.

6.5 Storing non-certified potatoes and requirements

Non-certified potatoes from another farm are not permitted to be stored with certified seed potatoes as they pose a risk of introducing pests or diseases.

If non-certified potatoes from another farm are found on the farm unit, including in a potato storage, it will result in the revocation of the crop certificate for the farm unit and the decertification of all seed potatoes stored in the same common facility.

7. BRR related requirements for established seed potato grower and field grown seed potatoes

Information on:

• application requirements
• document for seed potato shipments
• annual testing requirements for an established seed potato grower
• testing results

For new growers and growers re-entering the program after a detection, refer to section 9.

7.1 Application requirements

A seed potato grower must submit the Application for Seed Potato Crop Inspection (CFIA/ACIA 1317) on or before June 30 each year. The following will define the grower's farm unit for the crop year:

• fields
• seed potato varieties
• non-certified potato varieties

Testing for the presence of BRR is critical to maintain a grower's eligibility under the program and growers must submit relevant testing records with their application. In addition, certification documents (see section 7.2), must be provided to demonstrate that the seed potatoes shipped to their farm are certified for use in the program.

7.2 Documentation requirements for the movement of certified seed potatoes

The following documents may only be issued once:

• the issuance of the Growing Crop Certificate (CFIA/ACIA 1318) by the CFIA
• verification that the testing requirements have been met

Each document will state the certificate number which identifies the crop and year of production.

7.3 Annual testing requirements for field grown seed potato lots and procedures

Identifying situations where BRR testing is required including:

• sampling procedures
• sample submission to CFIA-approved laboratories
• testing results

7.4 BRR testing results

8. Investigation procedures

Here are the steps that must be undertaken following the detection of BRR on a seed potato farm unit.

An investigation begins when the CFIA Charlottetown Laboratory confirms a detection on a seed potato farm unit. The investigation is essential and its purpose is to delimit the potential spread of BRR and to identify any other farm units that may have been affected.

Cooperation and assistance from the grower are essential to conduct the investigation (see section 5.1 on a grower's duty to provide reasonable assistance). There are no CFIA fees associated with the investigation, including for collecting and testing samples.

8.1 Initial response when BRR is detected on a seed potato farm unit

The CFIA contacts the grower to:

• explain the situation
• share the test result from the CFIA Charlottetown Laboratory
• explain what immediate actions are required by the grower
• outline documentation requirements
• outline next steps (testing and sampling requirements, see section 8.3)

8.2 Grower's records to support the investigation

Growers must provide CFIA inspectors with records and/or statements regarding:

• equipment disinfection logs
• seed potato tags, record of bulk movement and certificates of authorization
• disinfection protocols
• disinfectants used on the farm unit
• planting records and planting sequences
• details of any shared potato handling equipment
• records related to the movement of seed potatoes from the farm unit
• records related to the movement of equipment from the farm unit

8.3 Testing on the farm unit and trace-back investigation

• A CFIA inspector may issue notices of detention to hold lots for testing
• A CFIA inspector must issue a Revocation of Certification (CFIA/ACIA 2546) listing all the seed potato lots on the farm unit

Lots from other farm units in a common storage facility will also be decertified.

• the lot that originally tested positive will not be resampled
• the CFIA will conduct sampling and testing on the farm unit of all other:
  • lots
  • seed potatoes
  • non-certified potatoes

The purpose of this testing is to determine:

• how widespread the infestation is on the farm unit
• identify the production fields associated with infected lots
• to determine all potential sources of the infestation, including source farm unit (trace-back investigation)

8.4 Sampling rates and testing during an investigation

During an investigation, CFIA inspectors will collect tuber samples at the rates defined in appendix 4, from:

• all lots on the index farm unit except for the initial lot(s) where BRR was detected
• any additional farm units where proper phytosanitary separation was not maintained (shared equipment without complete records of proper disinfection shared storage)

8.4.1 Testing of sister lots or seed source farm units

Sister lots can assist in determining whether the seed source was the point at which BRR was introduced to the index farm unit. If no sister lot is available, the CFIA must test all lots on the seed-source farm unit; see appendix 5.

• sampling and testing of sister lots and seed source farm units are given priority to ensure that if BRR is not detected, the seed source farm unit can resume operations as soon as possible
• all shipments of seed potatoes from a farm unit where sister lots are available for testing or from a seed source farm unit must be suspended, pending the outcome of the testing

The growing crop certificate (CFIA/ACIA 1318) is not revoked at this time and will only be revoked if BRR is detected on the farm unit, see diagram 1, appendix 5.

• in cases where sister lots are not available or where two or more sister lots from the same seed source test positive, all lots of the seed source farm must be tested, see diagram 2, appendix 5

8.5 Grower notification and outcome of the investigation

The CFIA will provide written notification of the testing results:

• will offer guidance on future eligibility for certification (see section 9), including expectations for cleaning and disinfection actions taken by the grower and obtaining a Disinfection Report (CFIA/ACIA 2415)
• request in writing the growers' decision to exit the seed certification program

9. BRR-related requirements for new seed potato growers and farms re-entering the CSPCP

Growers entering or re-entering the program, either as new seed potato growers or growers who wish to re-enter the program following an outbreak and decertification must meet several mandatory requirements. These requirements are in place to demonstrate compliance with the zero-tolerance standard for BRR on a seed potato farm unit.

The table in appendix 6 is provided to highlight the requirements for new growers and growers who seek to re-enter the program.

9.1 Cleaning and disinfection requirements

All of the following must be cleaned and disinfected with a disinfectant registered for the control of BRR prior to the arrival of any seed potatoes:

• potato handling equipment
• storage facilities
• tote boxes
• other equipment associated with the production of potatoes on the farm unit

Cleaning and disinfection must be supervised by a CFIA inspector and documented using a Disinfection Report (CFIA/ACIA 2415).

For growers who wish to re-enter the program, this step may have occurred during the investigation process.

If this requirement has not been met, the application for crop inspection will not be processed. Any seed potatoes arriving in storage before this requirement has been met will be considered non-certified and excluded from the farm unit.

9.2 Management of volunteer potatoes in a field with BRR

Volunteer potato plants emerging from previously infected fields pose a significant risk of reintroducing the pathogen and undermining the farm unit's non-detected result status.

New growers must provide documentation showing that potatoes have not been grown in the field for the previous two years and records that volunteer potatoes have been controlled. Examples of records of volunteer control:

• herbicide treatments
• tilling practices

Growers who wish to re-enter the program after the detection of BRR must exclude fields where tubers with confirmed detections were produced, unless those fields have been free of potatoes and volunteer plants for the previous two calendar years regardless of end use.

The grower must submit a mitigation plan to the CFIA to demonstrate how volunteer potatoes have been managed in fields where there was previously a detection. This plan must cover a 2-year period prior to planting seed potatoes or include a declaration of intent to permanently exclude those fields from seed potato production within the farm unit.

The mitigation plan must include:

• field location
  • size
  • crop history record
  • detection date
• volunteer management strategy
  • crop rotation
  • herbicide
  • rouging
• verification records
  • monitoring logs
  • inspection reports for the field
  • audit reports for the field
• biosecurity measures (equipment cleaning protocols)

An inspector will not accept the crop application or conduct a field crop inspection of any fields previously infected if the grower has not demonstrated that the field has been free of volunteer potatoes for the previous two years.

Additionally, an inspector will not conduct a field inspection if the grower is a new grower or if BRR was detected on the farm unit and a Disinfection Report (CFIA/ACIA 2415) has not been completed.

9.3. Application process

A new grower or a grower who seeks to re-enter the program after the detection must submit a written request to the CFIA, to enter the program. This must be done prior to receiving any seed potatoes on their farm. The CFIA recommend that growers contact their local CFIA office as early as possible to ensure eligibility for the growing season.

The Application for Seed Potato Crop Inspection (CFIA/ACIA 1317) must be completed and submitted on or before June 30, each year.

• for new growers, a farm unit number will be issued once the inspector has approved that the requirements in sections 9.1 and 9.2 have been met
• for a grower who seeks to re-enter the program after the detection, the application will not be approved until the inspector has approved that the requirements in sections 9.1 and 9.2 have been met
• all fields (seed potatoes and non-certified potatoes) related to where tubers with confirmed detections were produced in the previous two years are not eligible for inclusion on the farm unit and will not be accepted on the application for crop inspection
• growers who request to re-enter the program after the detection will retain their previous farm unit number
• if a grower has been decertified due to BRR in the past three years, that grower must apply for re-entering the program (not as a new grower)

If any of these requirements have not been met, the application for crop inspection will not be accepted.

9.4 BRR testing for new growers

To demonstrate non‑detected result on the new seed potato farm unit, all lots of potatoes produced – including seed and non-certified potatoes–must be tested at the monitoring program rate (appendix 2), using the tuber sampling method at a CFIA-approved laboratory. The cost of testing is covered by the grower.

For the first year, sample collection must be conducted under the direct supervision of CFIA inspectors.

For years 2 and 3, sample collection may be supervised by the CFIA.

Field grown lots that are certified as Pre-elite and Elite I classes are excluded from this requirement.

9.5 Enhanced sampling program for growers requesting to re-enter the CSPCP

Over the next three calendar years after the detection, the grower must demonstrate to the CFIA that BRR was not detected on all lots on the farm unit, using the process outlined in appendix 7. Those include:

• planted
• cultivated
• harvested

9.6 Issuance of tags and records of bulk movement during the first 3 years after a BRR detection

During the first three years following the most recent detection, seed potato tags and records of bulk movement will not be issued for lots regardless of the class indicated on the Growing Crop Certificate (CFIA/ACIA 1318) such as those identified as:

• Pre-Elite seed potatoes
• Elite I seed potatoes
• Elite II seed potatoes

Lots listed on the Growing Crop Certificate (CFIA/ACIA 1318) as Pre-Elite or Elite I or Elite II may be sold but they will be designated as Elite III or a lower seed potato class on the seed potato tags, records of bulk movement or other documentation.

9.7 Return to certification

If BRR has not been detected during the enhanced sampling period (3-years), the grower will return to the monitoring program (section 7). The farm has demonstrated that BRR was not detected.

Appendix 1: Roles and responsibilities

Appendix 2: BRR monitoring program - Sample size

Appendix 3: Sampling procedures for seed potato growers

Tuber sampling

Tubers are best collected at the time they are harvested or brought into storage. Acceptable tuber samples are those collected when all of the tubers have an equal chance of being sampled and are representative of the entire lot. Samples should include a specific number of tubers collected from every load going into storage. Acceptable sampling options include:

• samples from every row
• set number of rows in the field
• collection of the required number of tubers from those left on the ground once a field is harvested

Once the tubers are in a storage bin, it is very difficult to collect a representative sample of the lot, therefore samples should be collected prior to storage.

Whole tubers or tuber cores may be submitted directly to the laboratory. If cores are shipped to the laboratory:

• original tubers must be kept by the grower in separate
• labelled (so it can be linked to a lot)
• sealed containers until test results are available

How to take a core from a tuber

Description for Potato diagram

Cores must be taken at the stolon attachment site and must be conical or semi-spherical in shape, approximately 1 cm in diameter at the top and 1 cm deep. Each core should weigh approximately 0.5 to 1.0 g and include as much of the vascular ring radiating from the stolon attachment as possible.

Combining samples

Because follow-up measures on a BRR positive sample are taken on a crop or lot basis, samples from each crop or lot must be submitted to the lab in a closed, separate bag and individually labelled (so it can be linked to a lot or crop).

Each sample received by the laboratory is logged separately according to the certification number. However, per the official protocols followed by the laboratories, samples for the same crop may be combined for testing purposes.

The maximum number of cores or stems that may be combined by the laboratory for testing purposes is 200 (bags containing more than 200 cores will be subdivided).

Tubers samples from different farm units may not be combined into one laboratory sample.

Since options are available for sample submissions to the lab, it is advisable to contact the lab manager to make appropriate arrangements.

Sample handling

Always use clean tools and containers to prevent cross-contamination. Keep samples cool and dry before shipping.

Sending samples

Send samples to a CFIA-approved laboratory list. Contact the lab in advance to confirm shipping instructions and timing.

Packaging and shipping

To ensure sample continuity from a specific crop or lot to the laboratory it is crucial to follow proper procedures for:

• packaging
• shipping
• identification

If sample integrity is in question, the sample will be discarded and a new sample must be submitted.

When more than one tuber or core sample are shipped in the same container, a complete content list of samples submitted must be placed on the top of each shipping container or with the bill of lading. This list must be signed by the collector.

To ensure sample continuity, packages must be properly sealed so that they cannot be tampered with or opened during transit without the laboratory being aware of this upon arrival of the samples. If sample integrity is in question, the sample will be discarded and a new sample must be submitted.

When outside temperatures are anticipated to drop below freezing (0°C), freezing of the samples must be prevented. Laboratory staff will reject any samples showing signs of freezing.

Tubers must be as dry as possible before packing. If tubers are sent in bags, tags bearing proper identification of the sample must be present both inside and attached to the outside of the bag (on top of the tubers). This is to identify the sample in case the outside tag is lost or damaged during transportation.

Cores dried and wrapped in paper towels, may be kept in cold storage (4°C) for a maximum of 14 days before processing by the laboratory; refrigeration at all times is important. Cores that become decayed during storage will be discarded by the laboratory and a new sample requested.

Cores must be as dry as possible before packing. If using plastic sealable bags, ventilation holes must be present in the surface. Some manufacturers of plastic bags for retail sale (for the purpose of refrigerating vegetables) are now offering finely perforated sealable plastic bags, which can be used very successfully for potato cores. Cores may also be wrapped in paper towels and shipped in plastic bags. Each bag must be properly identified. Bags must be closed and refrigerated as soon as possible and no more than 2 hours after coring sampling. The bags should be kept in cold storage (4°C) overnight and in such a way (that is, well spread out) that the complete sample is brought down to 4°C before shipping. The sample size indicated on the bags must be correct: the lab will only accept a 2% deviation from this number.

Bags of samples should be packed loosely in insulated cardboard boxes. Ice-packs should be included on top of the samples (as cold air moves downward) but should be sufficiently insulated from the samples so that freezing is avoided.

Ice-packs are effective only for a short period: 24 to 48 hours depending on insulation. Therefore, shipment of samples must be postponed if the package is likely to be held in transit over a holiday or weekend, except if refrigerated storage is available.

Sample identification

Each sample must be clearly labeled with:

• lot number
• variety
• farm unit
• date of sampling
• name and contact information of the grower or sampler
• field/lot size in hectares

Appendix 4: Sampling rates during a BRR investigation

Appendix 5: Flow charts for BRR testing once it has been detected on a seed potato farm unit

Description for Diagram 1 - Trace-out sister lots

When a BRR positive lot is detected on a farm unit and sister lots are available, all available sister lots should be tested using 2000 tubers per lot. If any sister lot is found to be positive, all other lots on the seed source, affected and contact farm units must be tested using 1000 tubers per lot. If any of these lots are positive, each must be tested; if all are negative, testing can stop.

Description for Diagram 2 - Trace-out, sister lots are not available to test

When a BRR positive lot is detected on a farm unit and there are no sister lots available, testing must also be conducted on all lots (seed and non-seed) from the seed source farm unit using 1000 tubers per lot. If any lot from either the affected/contact farm units or the seed source farm unit tests positive, the process must restart from the beginning with the newly identified positive lot. If all tested lots are negative, the investigation is completed on seed source farm unit.

Appendix 6: Summary requirements

Appendix 7: Enhanced sampling rates