PI-005: Chapter 7 – Harvest/Bin Inspections
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Table of Contents
- 7.1 Objective
- 7.2 Definitions
- 7.3 Harvest Inspection
- 7.4 Bin Inspection
- 7.5 Sampling
- 7.5.1 Inspector Sampling and Testing
- 7.5.2 Bacterial Ring Rot
- 7.5.3 Post Harvest Testing
- Appendix 7 - 1 Forms Used in Harvest/Bin Inspections
7.0 Harvest/Bin Inspections
Inspections in the field and in storage primarily assess the general quality of the seed potato. Inspections are used to maintain lot identity and to determine the extent of potential problems that may express themselves at the time of shipping or in field performance.
These harvest/bin inspections can be performed to estimate total seed potato production for statistical reporting, offer advice to growers on proper tuber handling procedures, and assess potential storage problems due to disease pathogens (e.g. late blight, Phytophthora infestans and leak, Pythium spp.) or abiotic interactions (e.g. freezing or frost). Special attention should focus on lots or fields that have been subject to extreme conditions, either during the growing season or in storage.
This chapter will identify what the inspector should look for in the product during harvest and storage, as well as information on the various types of Post Harvest Tests and their sampling protocols.
- Bacterial Ring Rot; the disease caused by the bacterial pathogen Clavibacter michiganensis subsp. sepedonicus;
- Seed potatoes established in Section 47 of the Seeds Regulations Part II;
- Composite sample:
- The number of stem segments or tuber cores that may be combined into one unit for processing by the laboratory protocol;
- Any Breeders 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;
- Potatoes discarded or rejected as being worthless due to size, shape, injury, disease, etc.;
- Farm unit:
- A single tract or a number of separate tracts of land under the same or different tenure operating as a single unit which uses common equipment, facilities or storage for the production and marketing of seed potatoes under the control of a grower;
- The identifiable area of land on which seed potatoes of a particular variety and class are planted or have been produced;
- Field sample:
- The number of plants or tubers to be selected at random per field or lot identified by one certificate number, from which tissue is to be collected for testing;
- A person, cooperative, corporation or partnership that grows seed potatoes;
- Internal Brown Spot; a physiological disorder that may be associated with mineral deficiencies;
- Laboratory tests:
- Tests that are conducted in a laboratory that is accredited under the CFIA Laboratory Accreditation Program or equivalent;
- Means the quantity of harvested seed potatoes of a variety and class, including breeder's selection, that is identifiable by one certificate number;
- Laboratory Sampling Tracking System
- North American Certified Seed Potato Health Certificate; required by other certification agencies to substantiate the disease, health status and certification of a seed potato lot;
- Net necrosis:
- Death of phloem tissues in tubers, causing a netlike pattern of internal discolouration;
- Official protocols:
- Protocols that must be followed by CFIA accredited laboratories to perform specific diagnostic tests;
- Potato Leaf Roll Virus;
- Post harvest test (PHT):
- A visual or a diagnostic assessment performed on a sample of a lot in the current year after the crop is harvested and stored to determine the level of disease associated with that lot;
- Potato Spindle Tuber Viroid;
- Potato Virus X;
- Potato Virus Y;
- A random non-biased representation of a shipment whether it consists of packages (e.g. sacks, bags, crates, boxes, barrels) or bulk containers;
- Sample size:
- 1% of the product shipped;
- Seed potato:
- A tuber, or any part of a tuber, that is certified pursuant to the Seed Regulations Part II for seed reproduction purposes;
- The underground stem of a plant, the end of which may form a tuber;
- Tuber unit:
- The separate pieces of one tuber that are planted consecutively in two or more hills in a row;
- Tobacco rattle virus; also known as corky ring spot or spraing;
- Vascular ring:
- Tissue consisting of vascular strands grouped in a circular arrangement (viewed in a cross section) in a stem or tuber.
7.3 Harvest Inspection
The harvest inspection is performed in the field and takes place as the seed crop is being dug and put into storage. The inspector can vary the inspection and observe any facet of the harvest from digging to the placement of lots in storage at the bin piler. A minimum of one harvest inspection of at least one seed lot per farm unit is recommended, but if possible more lots should be inspected. In some circumstances, tuber diseases and physiological attributes of a crop may necessitate additional inspections.
During the harvest inspection, the inspector should:
- Determine the overall conditions of the crop as it is being harvested by direct observation in the field, on the harvester, or unloading the bulk boxes in storage. This is done to evaluate possible problems which may affect the quality of the crop.
- Observe and assess the grower's harvest operation.
- Assess a large number of tubers as product passes over harvesting equipment, thus increasing the probability of identifying diseased tubers, such as BRR, scab and rhizoctonia. Ensure a report is written for each lot examined.
- Supervise sample collection for BRR testing or any other post harvest testing options being pursued by the grower for specific market purposes. This phase is optional, but inspectors are advised to instruct growers on proper sampling techniques so that random samples drawn from each load transferred to storage from the field are suitable. This procedure is not required for all samples submitted, but reinforces seed grower's confidence as to correct procedures.
7.3.1 Materials Required for Harvest/Bin Inspection
To conduct the harvest/bin inspection, the inspectors should have the following items:
- Application for Seed Potato Crop Inspection Growers Declaration (CFIA/ACIA 1317) - PDF (135 kb);
- Seed Potato Tuber Inspection Report (CFIA/ACIA 3076) - PDF (74 kb);
- Identification Tag of Seed Potato Lots (CFIA/ACIA 0092);
- Harvest/Bin Inspection Procedures;
- Seeds Regulations Part II;
- Inspectors designation card;
- Metric tuber size gauge;
- Approved disinfectant (mixed to label rates), sprayer and brush;
- Sample bags;
- Hand lens;
- Appropriate footwear, sun screen, protective clothing (e.g. rain gear, hat, dust mask, gloves, etc.);
7.3.2 Harvest Inspection Procedure
When conducting a harvest inspection, the inspector should:
- Thoroughly disinfect inspection equipment (e.g. knife, boots, etc.). This will reduce the chance of transmitting any viral or bacterial disease onto the farm unit.
- Inspect tubers either in the field, on the harvester, and/or during the unloading and binning operations.
- Observe operation of equipment. Check the rate of tuber flow over the conveyors and the distance that the tubers are dropped during the harvest operation. Recommend changes or improvement to tuber flow that will reduce damage.
- Observe general condition of tubers taking note of:
- Tuber maturity - skin flaking or sloughing
- Tuber damage - sunburn, frost damage, bruising
- Tuber shape - malformed tubers
- Tuber size - excessively large or small.
- Observe external tuber disease symptoms (e.g. Scab and Rhizoctonia, blight, pythium, pinkeye, silver scurf).
- Cut tubers to look for physiological or internal disease problems. Frequent cutting of suspect tubers should be done. Randomly cutting symptomless tubers should also be done to verify levels of infection. On lots showing no internal defects or disease, limit cutting to random samples. It is at the discretion of the inspector as to the level of sampling confidence required.
Internal defects include:
- Vascular breakdown or discolouration and bacterial ooze caused by BRR;
- Net necrosis; and
- Stem end discolouration caused by top-killing, frost, heat or drought, verticillium wilt.
When these defects are encountered, the inspector should inform the grower. For additional information on the internal defects listed above, refer to the references cited in Chapter 4 of this manual.
Tubers suspected of being infected with BRR should be collected and sent to the Centre of Expertise for Potato Diseases, Charlottetown, PEI for confirmation. Complete the Report of Bacterial Ring Rot Specimens (CFIA/ACIA 1319) and notify grower of sample. For diagnostic confirmation of other suspect tubers, contact the Centre of Expertise for Potato Diseases, Charlottetown, PEI for information regarding submission of samples.
- Make a generalized assessment of the amount of grade-out (i.e. culls) of lots that are going to be sold. It is not necessary to calculate the culls for lots to be replanted on the farm. Take samples from the conveyor occasionally and make tuber counts. Samples of 100 tubers will allow grade-out levels to be calculated with a fair degree of ease and accuracy.
- Check storage separation between classes and varieties to maintain seed lot identity.
- Record valuations in the Harvest section of the Seed Potato Tuber Inspection Report (CFIA/ACIA 3076) - PDF (74 kb).
7.4 Bin Inspection
The bin inspection is performed in the storage facility. The inspector should observe storage layout and environmental conditions (e.g. extremes in temperature, humidity, etc.). This is an opportunity for the inspector to find potential disease problems before it becomes a threat to the lot. The bin inspection gives the inspector and producer information used to determine lots which may require additional attention while in storage.
It is the responsibility of the farm unit to store each lot in such a way that prevents varietal mixture and mixture with non-certified potatoes. If two lots of different classes of a single variety are stored in the same bin without separation to prevent the mixing of classes, then the seed potatoes will all be given the certificate of the lot with the lowest class. If multiple lots of the same class of a single variety are stored in the same bin without separation, then the seed potatoes will be given the certificate number of the lot with the highest disease percentage. Before the Growing Crop Certificate (CFIA/ACIA 1318) is issued, the inspector and the grower must discuss the combining of fields and certification numbers. In the event that the fields were combined after the certificate was issued, the Growing Crop Certificate (CFIA/ACIA 1318) must be amended and reissued. It is also the responsibility of the farm unit to identify each lot in storage according to the name of the applicable class as established in Section 47 or 61.1 of the Seeds Regulations Part II.
During the bin inspection, the inspector should:
- Assess the seed storage conditions;
- Verify lot identification, confirming location and separation of various classes and varieties in storage; and
- Consult with the grower to optimize potato storage conditions, thereby increasing marketability to minimize deterioration of the crop.
The basic equipment required is the same as for harvest inspection (see Section 7.3.1 of this chapter).
7.4.1 Bin Inspection Procedure
When conducting a bin inspection, the inspector should:
- Disinfect inspection equipment thoroughly (e.g. boots, knife, etc.).
- Observe the general conditions in the storage:
- Presence of moisture or frost in the wall or ceiling;
- General sanitation practices.
Part of this observation will include walking up to the face of the pile and taking tuber pulp temperatures in several locations. Proceed to the top of the pile (if possible) and compare temperatures from the top to the face of the pile. Large differences in temperature will indicate poor air circulation or disease problems in storage.
- Locate the various classes and varieties in the storage to determine adequate separation between lots. Adequate separation can be defined as a physical barrier that precludes the mixing of two lots. A mark on the wall of the storage bin is not considered to comply with the definition of a physical barrier. Netting, stacked bulk bins, and/or physical partitions are considered adequate.
- Ensure bins are accurately identified by an Identification Tag of Seed Potato Lots (CFIA/ACIA 0092) or other means and attached to the proper storage bin or pallet box. The inspector should have a storage map indicating locations of all seed potato lots stored on premises.
- Observe the appearance of the face of the bin and look for indications of active disease, such as:
- Depression in the pile;
- Excessive moisture running from the pile;
- Strong odours emanating from the pile; and
- Excessive amounts of mycelial growth on the surface of the pile.
- Inspectors can calculate the relative amount of grade-out which can be expected from each seed lot by evaluating tuber quality.
- Cut a number of tubers at random to check for internal symptoms of BRR, PLRV and other diseases.
- Calculate the grower's total production from the volume of seed that is in storage and refer back to field reports to relate production to field size. Yields should be reasonable for production of that variety under those growing conditions.
- Discuss with the grower results of inspection regarding storage problems, grading problems, grade regulations, etc.
- Complete the Seed Potato Tuber Inspection Report (CFIA/ACIA 3076) - PDF (74 kb).
When potatoes are being harvested and stored, representative samples are critical to the overall integrity of the lot within the certification program. With the transfer of testing to private laboratories accredited by the CFIA, and with the increasing involvement of the grower in the sampling procedures, the accuracy of sampling is imperative. A sample can be defined as a random non-biased representation of a shipment or lot, whether it consists of packages (e.g. sacks, bags, crates, boxes, barrels) or bulk containers.
Samples are to be collected by the grower as instructed by a CFIA inspector. Plants or tubers for sampling must be selected at random to provide an unbiased sample representative of the whole field or lot. Tubers are best collected at the time they are harvested or brought into storage when all tubers are equally accessible. The best way to obtain a random sample is to collect tubers from each harvested truckload as they are unloaded into storage. Virus levels may be higher or lower in different parts of a field, but sampling each truckload will ensure that a random sample has been taken.
When a sample is not collected from each truckload as they enter storage, it is important that growers are reminded not to pick the sample from the face of the pile. Growers should collect the sample from across the top of the pile, ranging from the front to the back of the storage.
Ensure that the sample is stored in a cool storage (i.e. 6-10°C) until shipped. This chilling process helps to break dormancy for better sprouting and emergence of the sample being tested.
The following sections contain the guidelines for testing required for field grown seed potatoes, including when the samples are to be collected and the required size. Various options, including specific sampling protocols, are outlined.
7.5.1 Inspector Sampling and Testing
An inspector may collect diseased tuber samples at harvest or bin inspections for submission for confirmatory testing. BRR, virus and PSTVd samples should be sent to the Centre of Expertise for Potato Diseases, Charlottetown, PEI for analysis. For other tuber disease samples, inspectors should contact the Centre of Expertise for Potato Diseases, Charlottetown, PEI for submission instructions. Samples can also be collected for various export markets, as well as for the post harvest virus assessment. All samples must maintain their integrity throughout the testing system and be properly identified with grower name, certification number, class, variety and date collected, signed by the collector. Non-BRR samples can be submitted using LSTS Plant Health Submission Sample Form (CFIA/ACIA 5161 PEI). BRR samples can be submitted using CFIA/ACIA 1319.
184.108.40.206 Procedure for Submission of Suspect BRR/Viral Samples
Samples submitted at harvest or bin inspection for confirmation of bacterial and viral infections (e.g. a tuber submitted for confirmation of BRR) must adhere to the following procedure:
- The inspector collects the sample from the field or bin personally, and ensures that the tuber(s) are as dry as possible before packing.
- The inspector collects the sample in a bag (not plastic) and writes the grower's name, certification number, date, variety and class on the bag and on a tag inside the bag with the sample.
- The inspector signs the bag and notifies the grower that he/she is submitting a sample for laboratory confirmation.
- The inspector completes a Report of Bacterial Ring Rot Specimens (CFIA/ACIA 1319) which must accompany the sample. Non-BRR samples can be submitted using LSTS Plant Health Submission Sample Form (CFIA/ACIA 5161 PEI).
- The lab personnel performs the proper tests and notifies the program officer, inspector and supervisor of the results.
Inspectors should make every effort to ensure that samples do not freeze. Laboratories will reject any samples showing signs of freezing. Packages must be properly sealed so that nobody can open or alter them while in transit, without the lab personnel being able to notice it upon arrival.
7.5.2 Bacterial Ring Rot (BRR)
All certified lots (except for Pre-elite, Elite I, and Certified classes that are sold or moved from a farm unit) must be tested for Clavibacter michiganensis subsp. sepedonicus. Moreover, a minimum of two lots per farm unit, destined for planting, must be tested. Testing options include stem sampling before harvest or tubers collected after harvest.
The minimum testing is two seed lots per farm unit. However, in cases where no lots (or only one) are grown and/or the lots are not being sold for seed, the inspector and the grower should discuss which lots are to be tested. Note that the final selection decision rests with the inspector.
For more information refer to the directive D-97-12: Seed Potato Certification Program-Interim Bacterial Ring Rot Testing Program For Field Grown Potatoes.
220.127.116.11 Sample Size
The sample size for stems extracted from the field or tubers collected in storage are given in Table 7.1: Field Sample Size for BRR Testing.
Table 7.1: Field Sample Size for BRR Testing
The following table outlines field sizes and corresponding sample sizes for Bacterial Ring Rot (BRR) testing.
|Field Size||Sample Size|
|1.000ha or more||400 stems or tubers|
|0.500ha to less than 1.000ha||200 stems or tubers|
|0.250ha to less than 0.500ha||100 stems or tubers|
|0.025ha to less than 0.250ha||50 stems or tubers|
|less than 0.025ha||1.0% of plants or tubers (min. 5; max. 50)|
18.104.22.168 Stem Samples
Stem samples are to be collected only after the field has been grown for at least 75% of the crops growing days, up to a maximum of 90 days. Only one stem is to be sampled per plant (i.e. each segment must come from a different plant). The samples must be selected at random, covering the whole field.
The tissue samples being submitted for testing must be approximately 1.0 cm long and sampled at soil level. Each stem segment must weigh between 0.5-1.0 g.
For more information refer to the directive D-97-12: Seed Potato Certification Program-Interim Bacterial Ring Rot Testing Program For Field Grown Potatoes.
22.214.171.124 Tuber Samples
The best time to collect tubers is at the time of harvest or when they are brought into storage and all the tubers are equally accessible. With tuber samples, whole tubers or tuber cores may be submitted directly to the laboratory. If cores are shipped to the lab, the original tubers must be kept and identified by lot certificate number, by the grower, in a sealed container, until test results are complete.
Cores are to be taken at the stolon attachment site and are to be cone or semi-spherical in shape, approximately 1 cm in diameter at the top and 1 cm deep. Each core should weigh between 0.5-1.0 g and include as much of the vascular ring radiating from the stolon attachment as possible.
Note: Follow-up measures on a positive sample are taken on a field or lot basis. Therefore, samples from each field or lot must be submitted to the lab in a closed, separate bag, and individually labelled. Although each sample is logged in separately by the laboratory based on its certificate number, according to official protocols followed by the labs, samples may be combined for testing purposes. Samples from different farm units may not be combined into one laboratory sample.
Inspectors should consult the directive D-97-12: Seed Potato Certification Program-Interim Bacterial Ring Rot Testing Program For Field Grown Potatoes for more information on BRR testing, sampling, packaging and shipping protocols.
126.96.36.199 Identification of Samples
Samples from each field or lot must be submitted in a closed, separate bag, and individually labelled. The following information is required on each label:
- Grower's name;
- Variety name;
- Maturity status or anticipated number of growing days (only required if stem samples used);
- Certificate number;
- Class (to be assigned/already assigned);
- Number of field sample units (i.e. number of stems or tubers);
- Date planted (for stem samples only);
- Date collected;
- Grower's or representative's signature;
- Inspector's signature, as required when collected by, or under the supervision of the inspector;
- Test for which sample is submitted (i.e. BRR).
188.8.131.52 Accredited Laboratories
Routine BRR testing in Canada is now being done by private labs under an Accreditation and Quality Assurance Program, administered and audited by the CFIA Centre of Expertise for Potato Diseases, Charlottetown, PEI. All accredited laboratories follow the same official protocols, and are evaluated on a regular basis to ensure these protocols are being adhered to. All positive samples must be confirmed by the Centre of Expertise for Potato Diseases, Charlottetown, PEI.
To aid inspectors in directing growers, a list of non-federal laboratories accredited for BRR testing may be obtained from:
Canadian Food Inspection Agency
Plant Health and Biosecurity Directorate
Horticulture Division, Potato Section
7.5.3 Post Harvest Test
Virus testing provides important information for marketing and crop assessment. Many buyers today understand the importance of a PHT assessment. Two common PHT assessment methods include winter grow out and lab testing for PLRV and PVY. Late season virus transmission by aphids after completion of field inspections, may result in increased levels of virus in a seed potato crop. A progeny evaluation of a lot in a Southern grow out location, laboratory testing of leaf samples from the grow out site, or tuber testing (of sprouts or greenhouse grown plants) by an accredited lab will provide additional information to growers, buyers, and inspectors as to the disease status of the lot.
Some countries, processors, and seed potato buyers require virus testing on seed potatoes for certification. A North American Seed Potato Health Certificate (NASPHC) is issued by the CFIA and is now required for recertification in the USA. When completing this form, post harvest test results are included.
Note: Virus testing after harvest is not regulated under the Seed Potato Certification Program.
184.108.40.206 Virus Test Sampling
Samples of potato lots are collected at harvest time (random sampling of tubers throughout the field) and tested during the winter. These tests may be in the form of a laboratory or a field test, and are used to determine acceptability of a seed lot for shipping or planting. Export markets may have specific testing requirements prescribed by import permits or bilateral protocols.
It is the grower's responsibility to collect winter test samples at the time of harvest. A few tubers should be selected from each load as the potatoes are hauled from the field or random samples collected at the bin piler as tubers are going into the bin. Tubers selected should be in the range of 1½ - 3oz. or 20-40 mm (3/4 -11/2 in) in greatest dimension for round varieties. Sample size is 400 tubers (+10%) and should be placed in new jute sacks or mesh onion sacks. Sized correctly, the sample should fit in a 22.7 kg (50 lb) sack. Onion sacks are recommended as the best container for effective dormancy breaking. Identification tags should be placed inside and outside the sack in case the outer tag is lost in transit or dormancy breaking process. These tags should be waterproof, smudge proof and tear proof (Tyvek) so that they maintain their integrity throughout. The inspector should audit samples taken by the grower to ensure that lot integrity is maintained.
Appendix 7-1 Forms Used in Harvest/Bin Inspection
7-1.1 Identification Tag of Seed Potato Lots (CFIA/ACIA 0092)
This tag is used by the grower and the inspector to identify the variety and class of seed potato stored in the storage bin or bulk boxes. This tag must be completed at harvest time during bin inspection.
7-1.2 Growing Crop Certificate (CFIA/ACIA 1318)
This certificate specifies the variety, class, area, and the certification number of every lot certified as seed potato on the farm unit. This is a single document to grant certification on all crops meeting the class standard for a given applicant.
7-1.3 Bacterial Ring Rot Specimens Report (CFIA/ACIA 1319)
The inspector includes this form with the sample to be tested for Bacterial Ring Rot. The inspector completes the top and the bottom portion of this form.
7-1.4 Seed Potato Tuber Inspection Report (CFIA/ACIA 3076) - PDF (74 kb)
This form is used by the inspector at time of harvest to assess the tuber conditions of the potato crop. Estimated production and estimated grade out figures are also to be included.
7-1.5 Plant Health Submission Form (CFIA/ACIA 5161 PEI)
The inspector includes this form with the sample for Disease Testing. The LSTS is currently under review and changes or updates will follow.
Appendix 7-1.2 Growing Crop Certificate (CFIA/ACIA 1318) – Example
The following image is an example of a Growing Crop Certificate (CFIA/ACIA 1318).
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