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New Seed Extract (SE-PCR) test for onion, chives, garlic and leek

Publicationdate: 8 april 2024

Starting April 1, we can test the presence or absence of Xanthomonas axonopodis pv. allii on seeds of onion, chives, garlic and leeks. For this test we have chosen the fast, reliable and sensitive Seed-Extract PCR (ZE-PCR) method.

The SE-PCR is a technique for rapid DNA screening for the presence of pathogens

Whereas plating tests consist of multiple tests that follow each other and are therefore time-consuming, the SE-PCR is a rapid test. The PCR is done directly on the extract of the seed.

Next to the speed, another advantage is that SE-PCR has less interference from overgrowth by other micro-organisms on the seeds, as it can be the case with plating on selective media where we look at the growth of pathogens. The disadvantage is that we cannot distinguish between live and dead pathogens, therefore it is only a pre-screening.

The bacteria

Xanthomonas axonopodis pv. allii is the causative agent of Xanthomonas leaf wilt disease on onion crops (onion, leeks, chives, garlic). It was first observed in the 1970's in Barbados after which it has spread throughout the southern states of the US, Cuba, Brazil, Japan, southeast Asia and South Africa. The proven seed-borne pathogen can cause a loss in field productions of 20-50%.

Xanthomonas axonopodis pv. allii on onion, chives, garlic and leek seeds

  • Test code: XAAQ100
  • Sample: 10,000 untreated seeds
  • Test fee: € 207
  • Duration test: 4 days

To support the sector, Naktuinbouw Laboratories continues to develop new tests that can support diagnoses on plants and seeds with symptoms or just checking for and guaranteeing freedom from certain viruses.


For basic fees see price list 2024.

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