Dutch National Plant Protection Organization NPPO NL

Wageningen, Netherlands

Dutch National Plant Protection Organization NPPO NL

Wageningen, Netherlands
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Tjou-Tam-sin N.N.A.,Dutch National Plant Protection Organization NPPO NL | van de Bilt J.L.J.,Dutch National Plant Protection Organization NPPO NL | Westenberg M.,Dutch National Plant Protection Organization NPPO NL | Bergsma-Vlami M.,Dutch National Plant Protection Organization NPPO NL | And 5 more authors.
Plant Disease | Year: 2017

In August 2015, the Dutch National Plant Protection Organization (NPPO-NL) was informed on unusual disease appearances in plants of cut roses (Rosa sp. cv. Armando) in a greenhouse production site. The displayed symptoms were wilting of young shoots and flower stalks, yellowing and early abscission of leaves, stunting, dieback with black necrosis of pruned branches, and in some cases discharge of creamy white slime on cut wounds in the stem. Ambient temperatures in the greenhouses were 25 to 30°C. A bacterial wilt infection caused by Ralstonia solanacearum was suspected. In September 2015, the outcomes from diagnostic investigation by NPPO-NL on rose samples from this greenhouse confirmed that the uncommon symptoms were caused by R. solanacearum. This is, worldwide, the first documented report of R. solanacearum affecting Rosa sp. After this first finding, two other growers producing cut roses (Rosa sp. cv. Sativa and cv. Red Naomi, respectively) reported similar problems in their cultivation. The disease incidence at the three production sites varied from nil up to 50% in some greenhouse compartments. Tracking and tracing to unravel the pathway of infection revealed R. solanacearum infections at two nurseries producing Rosa sp. plants for planting. The primary origin of infection is under investigation but remains unknown at present. The bacterium was isolated from vascular stem tissue of symptomatic plants on semiselective SMSA medium as described in the annexes to Commission Directive 2006/63/EC (EU 2006). Isolates were identified as R. solanacearum by TaqMan real-time PCR (Weller et al. 2000) and immunofluorescence (IF) microscopy (EU 2006) using polyclonal antibodies (Loewe, Germany). Phylotype multiplex PCR (Fegan and Prior 2005) assigned the isolates to phylotype I. Testing the isolates for biovar determination (EU 2006), acid was produced from both the disaccharides and the hexose alcohols. After stem inoculation in tobacco (Nicotiana tabacum cv. White Brurley) for race determination (Buddenhagen et al. 1962) the plants showed wilting within 5 to 10 days. These tests attributed the isolates to biovar 3 and race 1. Pathogenicity of the isolates was tested on tomato plants cv. Moneymaker as described in EU (2006) and on cut rose (Rosa sp. cv. Lucky Red) by infiltrating a cell suspension in 10 mM phosphate buffer (~108 CFU/ml) at the base of a shoot of rooted cuttings. Test plants were incubated at 28/20°C day/night temperature. Rose shoots displayed sectorial wilting, chlorosis, and necrosis of leaves after 10 to 14 days while tomato plants wilted after 4 to 10 days. Completing Koch’s postulates, R. solanacearum was reisolated from the affected tobacco, tomato, and rose plants and reidentified by TaqMan PCR. Amplified fragment length polymorphism (AFLP) analysis (Vos et al. 1995) of R. solanacearum isolates from different ornamentals (including 11 isolates from cut roses) and other crops revealed that the isolates from cut roses cluster in a monophyletic clade, only distantly related to isolates from other crops included in the phylogenetic study. This suggests a single, recent introduction of R. solanacearum into the cut roses cultivation in the Netherlands. © The American Phytopathological Society.


Lombard L.,Fungal Biodiversity Center | van Leeuwen G.C.M.,Dutch National Plant Protection Organization NPPO NL | van Rijswick P.C.J.,Dutch National Plant Protection Organization NPPO NL | Rosendahl K.C.H.M.,Dutch National Plant Protection Organization NPPO NL | And 4 more authors.
Phytopathologia Mediterranea | Year: 2014

Species of the genus Vaccinium are commercially cultivated in Europe for their berries, which are highly valued for dietary and pharmaceutical properties. Cultivation is severely limited due to a range of fungal diseases, especially those caused by species of Diaporthe. A number of Diaporthe isolates have been collected from Vaccinium growing regions in Europe, and initially identified as D. vaccinii based on host association. Using DNA sequence inference of the combined β-tubulin, calmodulin, translation elongation factor 1-alpha and the internal transcribed spacer region of the nuclear rDNA, along with morphological characteristics, six species were characterised. Diaporthe eres, D. vaccinii and D. viticola are known species and three novel taxa are described here as D. asheicola, D. baccae and D. sterilis. This study is the first confirmed report of D. vaccinii in Latvia and the Netherlands. © Firenze University Press. © Firenze University Press.

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