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Phases of Nuclear Stock Class Seed Potato Production & Testing Requirements:
Three phases are recognized in the production of Nuclear Stock class seed potatoes.
Where pathogen-tested potato propagules are established in an aseptic environment through in vitro micro-propagation (e.g., tissue culture).
Where pathogen-tested potato propagules are maintained in an aseptic environment.
Where pathogen-tested potato propagules are increased through vegetative propagation in an aseptic environment and/or in a protected environment (e.g., greenhouse, screenhouse, growth chamber, etc.).
Each crop must have been found free from the following organisms:
VIRUSES: PVA, PVS, PVM, PVY, PVX, PLRV, PMTV and PotLV
BACTERIA: Clavibacter michiganensis subsp. sepedonicus, the causal pathogen for bacterial ring rot (BRR)
Each crop under production must have valid disease testing results at all times during the multiplication process, with the exception of micro-tuber production, where valid disease testing results are required at the initiation of the micro-tuber production cycle.
All disease tests must have been carried out by a laboratory approved by the CFIA and are valid for a period of 12 months commencing on the date that the sample was received for testing to the approved laboratory.
Sample Submission Requirements by Phase:
Disease testing of plantlets in an aseptic environment must be carried out on a minimum of two plantlets for each variety/clone and each variety/clone must be found free from the diseases identified above. Any potato material (e.g., any potato plant part, including stems and tubers) is acceptable for initiation into culture.
There are no requirements for specific disease testing during the maintenance of Nuclear Stock class seed potatoes in an aseptic environment other than, where maintenance takes place in a facility other than the initiating facility, the material must be certified as Nuclear Stock class seed potatoes prior to maintenance and possess disease testing results as described above.
For Nuclear Stock class seed potatoes in an aseptic environment the level of testing for each variety/clone under active multiplication will be 1% or a minimum of 5 plantlets to a maximum of 50 plantlets per clone.
The crop must be grown from Nuclear Stock class plantlets or micro-tubers which were produced in aseptic conditions, or from first generation Nuclear Stock class mini-tubers produced in the grower's own protected environment facility, or from stem cuttings produced in the grower's own protected environment facility that have been disease tested.
If first generation mini-tubers and/or stem cuttings are used to produce a second generation, a CFIA inspector shall not certify the second generation unless material from the first generation or the second generation have been tested by a laboratory approved by the CFIA and found to be free from the pathogens listed above.
When additional pathogen testing is required on a crop producing mini-tubers, samples for virus and viroid testing should be collected at budding/flowering time (approximately 40 -70 days after planting) and for Clavibacter michiganensis subsp. Sepedonicus, causal pathogen for bacterial ring rot (BRR) as outlined in the BRR submission guide. Testing must be done on a representative sample consisting of 1% of the plants/tubers with a minimum of 5 and a maximum of 50 plants/tubers sampled per lot. All plants and when applicable, at least one tuber per plant, must be tested if the total number of plants of the clone is less than 5. All samples taken for required pathogen testing must be collected by or under the supervision of a CFIA inspector.
Specifications for Samples Being Submitted:
Samples must be properly identified with completed Nuclear Stock Tags or the equivalent.
Protect against crushing, freezing or overheating by insulating and packing your samples carefully. Use an overnight delivery service to maintain sample integrity, especially when shipping perishable samples that may be destroyed in transit by exposure to prolonged shipping time and extreme hot or cold temperatures.
Ship early in the week (no later than Tuesday) to avoid having your sample sit over weekends or holidays and call or email ahead to let us know your sample(s) will be arriving to minimize any processing delays.
Phyto Diagnostics Company Ltd.
9381 Ardmore Drive
British Columbia, Canada
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