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Apeldoorn, Netherlands

Agricultural imports, particularly seeds, are an important route for introduction of alien plant species. This article discusses two studies on the occurrence of alien plants, especially from the genus Ambrosia, in batches of imported seeds. The pollen of Common ragweed {Ambrosia artemisiifolia), in particular, is known to trigger a severe hay-fever response in some people, thereby constituting a public health hazard. The first study is concerned with the contamination of kitchen herbs and of seeds processed in livestock feed and vegetable cooking oil with seeds of alien plants. In five products from six countries the seeds of at least 67 species were found. Of these, fifteen are registered as quarantine pests among which Common ragweed, Giant ragweed (Ambrosia trífida), a Blackjack species (Bidens pilosa), Johnson-grass (Sorghum halepense), and three Morning-glory species (Ipomoea spec). The second study investigates the occurrence of alien plant species as contaminants in 'birdseed' ingredients. The seeds used in this product were from fourteen crops and ten different countries. In addition, seventeen batches of mixed feed from Dutch shops were specifically examined for the occurrence of Ambrosia. Common ragweed was found in batches of Sunflower and Great millet seeds imported from France and Hungary. Of these Ambrosia seeds, 36% germinated within three weeks. In the mixed feed, Common ragweed was found in twothirds of the batches; of these seeds, an average of 13% germinated. In the batches of birdseed ingredients, another 27 non-indigenous and 15 naturalised alien plant species were encountered as well as 21 indigenous species. In these batches, seeds of 17 quarantine pests were found including Common ragweed, Johnson-grass, Velvetleaf (Abutilón theophrasti), Summer-cypress (Bassia scoparia), Cotton thistle (Onopordum acanthium), and Alligator weed (Alternanthera philoxeroides). The alien Hard-grass (Eleusine indica) was also found, known to be a persistent weed. The indigenous species posing the greatest risk of genetic contamination are Fat hen (Chenopodium album) and Pale persicaria (Persicaria lapathifola).

Kox L.,Plantenziektenkundige Dienst | Waeyenberge L.,Belgium Institute for Agricultural and Fisheries Research | Viaene N.,Belgium Institute for Agricultural and Fisheries Research | Zijlstra C.,Plant Research International
Journal of Phytopathology | Year: 2011

Meloidogyne minor is a small root-knot nematode that causes yellow patch disease in golf courses and severe quality damage in potatoes. It was described in 2004 and has been detected in The Netherlands, England, Wales, Northern Ireland, Ireland and Belgium. The nematode often appears together with M. naasi on grasses. It causes similar symptoms on potato tubers as M. chitwoodi and M. fallax, which are both quarantine organisms in Europe. An accurate identification method therefore is required. This study describes a real-time PCR assay that enables the identification of M. minor after extraction of nematodes from soil or plant samples. Alignments of sequences of rDNA-ITS fragments of M. minor and five other Meloidogyne species were used to design a forward primer Mminor_f299, a specific primer Mminor_r362 and the specific MGB TaqMan probe P_Mm_MGB321. PCR with this primers and probe results in an amplicon of 64 bp. The analytical specificity of the real-time PCR assay was assessed by assaying it on six populations of M. minor and on 10 populations of six other Meloidogyne species. Only DNA from M. minor gave positive results in this assay. The assay was able to identify M. minor using DNA from a single juvenile independent from the DNA extraction method used. © 2010 Plant Research International.

van Brouwershaven I.R.,Plantenziektenkundige Dienst | Bruil M.L.,Plantenziektenkundige Dienst | van Leeuwen G.C.M.,Plantenziektenkundige Dienst | Kox L.F.F.,Plantenziektenkundige Dienst
Plant Pathology | Year: 2010

To prevent the entry and spread of the brown rot fungus Monilinia fructicola in Europe, a fast and reliable method for detection of this organism is essential. In this study, an automated DNA extraction method combined with a multiplex real-time PCR based on TaqMan chemistry was developed for fast, convenient and reliable detection of both the EU quarantine organism Monilinia fructicola and the three other brown rot fungi M. fructigena, M. laxa and Monilia polystroma. Using the internal transcribed spacer (ITS) region of the nuclear ribosomal RNA gene repeat, a Monilinia genus-specific primer pair and two differently labelled fluorogenic probes specific for M. fructicola and the group M. fructigena/M. laxa/Monilia polystroma were developed. The analytical specificity of the assay was assessed by testing 33 isolates of the four brown rot fungi and 13 isolates of related fungal species or other fungal species that can be present on stone and pome fruit. No cross-reactions were observed. The assay was found to have a detection limit of 0·6 pg of DNA, corresponding to 27 haploid genomes or four conidia. Comparison of a manual DNA isolation followed by a conventional PCR with an automated DNA isolation combined with the presently developed real-time PCR showed that the latter method gave improved results when tested with 72 naturally infected stone fruit samples. The detection rate increased from 65 to 97%. © 2009 The Authors.

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