Seed Potatoes
Seed potatoes need reliable disease testing, backed by specialised knowledge. The NAK provides this as the independent knowledge authority for seed potatoes. Our laboratory analyses potato tubers for viruses, bacteria and nematodes, either in combination or separately.
We are unable to accept potato samples from non-EU countries for testing. This is due to changes in the regulations and requirements our laboratory must meet.
Potato tuber testing at the NAK
The NAK tests potato tubers for viruses and other diseases. This determines the disease status of the potatoes.
- Our laboratory tests tubers for several viruses and other diseases, using advanced laboratory techniques.
- Our laboratory technicians carry out the tests and assess the disease status of the potatoes.
- PCR is a laboratory technique that detects the genetic material of viruses and bacteria. With PCR, it is possible to combine tests for all listed diseases, or to choose a test for fewer diseases or a single disease. Sample sizes other than 200 tubers are also possible (see the price list).
- The standard sample composition for virus and Erwinia testing is 4 x 50. Other compositions are possible (see the price list). For a combination test, the sample size and composition must be the same for both the virus and the Erwinia test.
The NAK does not test samples that contain genetically modified material (GMO). Due to regulations and laboratory requirements, it is not possible to accept samples from non-EU countries for testing.
For more information, contact our Customer Service Department: 0031 (0)527-635350 or nak@nak.nl
Available tests
The NAK tests potato tubers for viruses, bacteria and nematodes. A single test or a combination of tests may be requested. All tests are carried out on a sample of potato tubers, using laboratory techniques such as PCR and IF-testing. IF-testing (immunofluorescence test) is a laboratory technique used to detect bacteria with antibodies.
Virus testing
Potato tubers are tested for different viruses using PCR. The standard test covers four types of viruses: PVY, PVA, PVX and PLRV (Potato Leafroll Virus). A PCR test can detect a maximum of four virus types. PVS can be tested on request.
| Examination method | PCR |
| Standard viruses tested | PVY, PVA, PVX, PLRV |
| Lead time | regular processing: 2 weeks or less (priority processing: 1 week) |
| Sample submission | Mesh bag, closed with a tie-wrap. Use a polypropylene bag for a combination test with M. chitwoodi/fallax and/or brown rot/ring rot. |
Sample size and testing options
| Sample size | Number of reactions | Tubers per reaction |
|---|---|---|
| 200 tubers | 4 | 50 |
| 200 tubers | 10 | 20 |
| 100 tubers | 10 | 10 |
| 50 tubers | 1 | 50 |
| 20 tubers | 1 | 20 |
Erwinia Testing (Bacterial Blackleg and Stem Rot)
Erwinia testing detects the bacteria that cause blackleg and stem rot in potato tubers. This test identifies latent infections of Pectobacterium atrosepticum (Pa), Dickeya spp. (Dic), Pectobacterium parmentieri (Pp), and Pectobacterium brasiliense (Pb).
| Examination method | PCR |
| Lead time | 3 weeks or less (priority: 2 weeks or less) |
| Packaging | Mesh bag, closed with a tie-wrap. Use a polypropylene bag for a combination test with M. chitwoodi/fallax and/or brown rot/ring rot. |
Sample size and testing options
| Sample size | Number of reactions | Tubers per reaction |
|---|---|---|
| 200 tubers | 4 | 50 |
| 200 tubers | 10 | 20 |
| 100 tubers | 10 | 10 |
| 50 tubers | 1 | 50 |
| 20 tubers | 1 | 20 |
Example: for a 4 x 50 test, a sample of 200 tubers is submitted. The laboratory divides the sample into 4 groups of 50 tubers. Each group produces one result, either positive or negative, for the bacteria tested.
Brown Rot and Ring Rot
This test detects latent infections of bacterial ring rot, caused by Clavibacter sepedonicus, and brown rot (bacterial wilt), caused by Ralstonia solanacearum.
If a sample tests positive for brown rot or ring rot, the NAK is required to report this to the Dutch National Plant Protection Organisation (NPPO), the Dutch authority responsible for plant health.
| Examination method | IF-test |
| Lead time | 2 weeks or less (priority: 1 week or less) |
| Packaging | Polypropylene bag, closed with a tie-wrap |
| Sample size | 200 tubers, tested as one sample |
If a sample fails to test negative in the IF-test, it is sent to the NPPO for confirmation testing. The full result of a positive sample is available between 2 and 15 weeks after the IF-test result.
Combining Tests
Several tests can be combined on one sample of 200 tubers. This reduces costs. The following tests can be combined on a single sample:
- Virus PCR (standard combination: PVY, PVA, PVX, PLRV)
- Erwinia (blackleg test)
- Meloidogyne chitwoodi and M. fallax
- Brown rot and ring rot
For a combination test, the sample size and grouping for the virus test and the Erwinia test must be the same. The standard grouping is 4 x 50.
Other Tests
If a required test is not listed here, or a price quote is needed, send an email describing the request to nak@nak.nl.
Test results
Results are sent by email as a PDF file. An Excel file is also available on request.
The number of positive (“diseased”) results is reported, rather than the disease percentage or spread. This number can be calculated using Seedcalc8, a free tool from the International Seed Testing Association (ISTA). The tool is available on the ISTA website. Scroll down to “Seedcalc8” and download the Excel file to get started.
Sending samples
Samples are accepted on weekdays, between 8:00 and 17:00, except on Dutch public holidays.
Notify the NAK at least three working days before sending samples. Send this notification by email to nak@nak.nl and include the following details:
- The expected delivery date
- The number of samples
- A choice of the tests to be carried out
Delivery address: NAK, Randweg 14, 8304 AS, Emmeloord, The Netherlands
Sample labelling
All samples should be labelled with unique NAK sample labels. A request for labels can be sent to nak@nak.nl. The labels are sent by post.
Each sample label consists of two parts. Attach one part to the outside of the sample bag and the other part to the inside of the bag. Each part is marked to show where it belongs: ‘aan’ (outside the bag) or ‘in’ (inside the bag).
Samples that arrive without pre-requested labels or without prior communication to the NAK cannot be processed.
Fees seed potato testing 2026-2027
| Description | Price | Notes |
|---|---|---|
| Virus examination PCR tubers* (PVY, PVA, PVX and PLRV) | ||
| Per sample of 200 tubers | € 157,50 | 4 subsamples of 50 tubers |
| Per sample of 200 tubers | € 240,65 | 10 subsamples of 20 tubers |
| Per sample of 100 tubers | € 227,85 | 10 subsamples of 10 tubers |
| Per sample of 50 tubers | € 65,55 | 1 subsample of 50 tubers |
| Per sample of 20 tubers | € 50,40 | 1 subsample of 20 tubers |
| Erwinia examination PCR-test* | ||
| Per sample of 200 tubers | € 163,75 | 4 subsamples of 50 tubers |
| Per sample of 200 tubers | € 250,25 | 10 subsamples of 20 tubers |
| Per sample of 100 tubers | € 236,90 | 10 subsamples of 10 tubers |
| Per sample of 50 tubers | € 68,10 | 1 subsample of 50 tubers |
| Per sample of 20 tubers | € 52,40 | 1 subsample of 20 tubers |
| Per sample of 200 tubers, in combination with PCR-virus | € 91,70 | 4 subsamples of 50 tubers |
| Brown rot/Ring rot test* | ||
| First screening (IF-test) | € 105,15 | Sample max. 200 tubers |
| Meloidogyne chitwoodi PCR test* | ||
| Per sample of 200 tubers | € 203,40 | 2 subsamples of 100 tubers |
| *Additional costs | ||
| Administration fee per request | € 18,35 | |
| Per sample | € 1,33 | |
| Storage of samples | € 4,25 | Per sample |
| Testing after 15 December | 25% addition on the mentioned prices | |
| Labels ordered, without laboratory test | € 46,30 | Per request |
| Priority test; extra charge per sample | € 131,00 |
*Fees are exclusive of VAT and valid until May 2027
Specific questions about tests, samples, analytical issues, or logistics can be sent to our Customer Service Department NAK 0031 (0)527-635350 or nak@nak.nl
Advice and support
For specific questions about tests, samples, analysis, or logistics, contact our Customer Service Department at +31 (0)527-635350 or nak@nak.nl.
The NAK’s standard terms and conditions for the supply of goods and services apply to all our activities.