Indicator plants at VWA for detection of virusses

Potato quarantine procedures

Phytosanitairy measurements are required by EU Directives to prevent the spread of new potato pathogens from South America into the European Union. The collection of wild and primitive potato species is maintained in the form of botanical seeds. Therefore only true seed transmittable diseases from the quarantine list need to be screened for. Andean potato mottle virus (APMV) is not transmitted by true seed.

July 1997 the European Commission has put Potato Yellowing Virus (PYV) new on the quarantine list and removed Arracacha virus B from it. However, 3 years later Arracacha virus B is on the list again and PYV removed (Council Directive 2000/29/EC). The directive is included into the Plant Health Regulations for the Netherlands. Information on Plant Passport obligations in the Netherlands is provided by the Dutch Ministry of Economic Affairs, Agriculture and Innovation. On 14 December 2019 the 2000/29 regulation was replaced by 2016/2031, including extended phytosanitairy obligations and plant passport use for more crops (info NVWA).

All plants used for rejuvenation are tested by the NVWA (Netherlands Food and Consumer Product Safety Authority [till 2009 Plantenziektenkundige Dienst]) in Wageningen. At the subsequent regeneration, botanical seeds are produced meeting the zero tolerance for quarantine diseases. Following pathogens are being tested:

  • Within the EU, Potato spindle tuber viroid (PSTVd) was a Q-organism till December 14, 2019, when it was classified as a Regulated Non-Quarantaine Pest (RNQP). The performed testing method "Return" - Polyacrylamide Gel electrophoresis (Huttinga et al., 1987; Roenhorst et al., 2000; Verhoeven et al. 2004; Verhoeven 2010), with a maximum bulking rate of 5 (till the year 2000, a bulking rate of upto 25) was used untill 2020. From 2019 onwards Real-time (RT-) PCR was performed on a bulk sample. Both are generic methods for the detection of Pospiviroids (incl. PSTVd).
  • True seed transmitted viruses: 1995-1999 using the indicator plants Chenopodium quinoa (or C. amaranticolor), Nicotiana oxidentalis-P1 and N. bentamiana, maximum bulking rate 5. Starting in 2000 in 2-fold C. quinoa (or C. amaranticolor) and in 4-fold N. hesperis-67A (or N. oxidentalis-P1) (Verhoeven & Roenhorst, 2003). Furthermore, the potato plants were weekly visually inspected. These procedures include screening for:

    • Andean potato latent virus (APLV)
    • Arracacha virus B - oca strain (AVB-O)
    • Potato black ringspot virus (PBRsV)
    • Potato virus T (PVT)
    • unknown viruses

For the test on quarantine viruses leaves are picked when the potato plants are about 25 cm tall. Three weeks after inoculation of the indicator plants the results will be available. In case of symptoms on the indicator plants the potato plants are retested serologically. It is assumed that the indicator plants will also show symptoms on infections with unknown potato viruses. Further on, all potato plants are visually inspected.

Till 1994

Till 1994 the German-Dutch Potato Collection was maintained in Braunschweig, Germany. From 1988 - 1994 the screening for quarantine viruses was carried out by the Plant Protection Service of the federal state Niedersachsen (Pflanzenschutzamt Hannover) using ELISA for APLV (Col, Hu, 300), APMV (B,C,H), AVB-O, PVT and TRSV-Ca (= PBRSV). The antibodies were produced by the Institute for Biochemistry and Plant Virology of the Federal Biological Research Centre for Agriculture and Forestry (BBA), Braunschweig. By the way, APMV (Andean Potato Mottle Virus) is NOT transmitted via TPS (botanical seed).

1986-1987 leaf samples were sent to the Dutch Plant Protection Service in Wageningen and tested with the Latex-agglutination test on APLV & PBRSV. Additionally, indicator plants (C. quinoa, C. amaranticolor & N. clevelandii) were used to screen for APLV, PBRSV, PVT and 'unknown' virusses.

For most recent true seed import demands of different countries download a PDF file per country from NVWA (click on "exportland"), only available in Dutch. Several countries do not require an import permit (incl. an adapted Plant Health Certificate) for material imported for research purposes. Examples of some foreign import requirements: Canada, Chile.

For importing potato germplasm in the Netherlands see (in Dutch): NVWA-import-vergunning, including a link to the import-request-form.

In case of vegetative propaged material

In case CGN would maintain vegetatively propagated potato plants, the Dutch Plant Protection Service would have used the indicator plants C. quinoa (or C. amaranticolor), N. hesperis-67A and N. occidentalis-P1, all in 2-fold. Additionally, ELISA tests need to be carried out on APLV, APMV, PBRSV, PLRV, PVA, PVM, PVS, PVT, PVV, PVX and PVY. Because PLRV can not be transmitted mechanically, an ELISA test on this particular virus need to be carried out twice, with an time interval of circa 3 weeks. All plants need to be screened individually. In addition this material needs to be is tested on PSTVd. This would fulfill the demanded screenings by EU regulation 2000/29.

Within the EU, also the user needs to supply a plant passport, when distributing this germplasm or derived material to other users in the EU, according to Council Directive 2000/29/EC (see page 87).


EPPO (European and Mediterranean Plant Protection Organization) is an intergovernmental organization responsible for European cooperation in plant health. It help its member countries to prevent entry or spread of dangerous pests (plant quarantine), by providing data sheets on the diseases (see A1-list and A2-list), maps, diagnostic protocols and pictures of symptoms and organisms.