Vinh Hong Le
Chief Engineer
Authors
Arne Stensvand Nan-Yi Wang Vinh Hong Le Claudio Dias Da Silva Belachew Asalf Tadesse Chloé Grieu William W. Turechek Natalia A. PeresAbstract
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Authors
Britt Puidet Romain Mabon Michele Guibert Riinu Kiiker Kaire Loit Vinh Hong Le Håvard Eikemo Pauline Dewaegeneire Guillaume Saubeau Catherine Chatot Frédérique Aurousseau David E. L. Cooke Alison K. Lees Isaac K. Abuley Jens G. Hansen Roselyne Corbière Melen Leclerc Neda Najdabbasi Didier AndrivonAbstract
Since the mid-2010s, Phytophthora infestans clones that have been dominant in Western Europe from the beginning of the 21st century, for example, EU_13_A2, EU_6_A1 and EU_1_A1, are being replaced by several other emerging clones, including EU_37_A2. The objective of this study was to determine whether the main drivers for the success of EU_37_A2 in Western Europe are associated with decreased fungicide sensitivity, increased virulence and/or aggressiveness. Axenic P. infestans cultures were sampled in the 2016 and 2017 growing seasons from potato crops in France and the United Kingdom. Amongst these, four genotypes were identified: EU_37_A2, EU_13_A2, EU_1_A1 and EU_6_A1. Although a wide range of fluazinam sensitivity was found amongst individual isolates, clonal lines EU_13_A2 and EU_37_A2 showed decreased sensitivity to fluazinam. EU_37_A2 overcame the R5 differential cultivar more often than isolates of EU_1_A1 or EU_6_A1. However, this does not explain the competitive advantage of EU_37_A2 over the virulent EU_13_A2. The fittest genotype, as measured by aggressiveness under controlled conditions, was EU_6_A1, followed by EU_37_A2, EU_13_A2 and then EU_1_A1. EU_37_A2 isolates also showed a shorter latent period than either EU_6_A1 or EU_13_A2, which could favour its long-term persistence. Overall, the data suggest that the emergence of EU_37_A2 in Western Europe was driven by its resistance to a then-major fungicide and shorter generation time. This conclusion is further supported by the fact that EU_37_A2 emergence was slowed by the progressive reduction in the use of fluazinam as a single active ingredient in the years following its initial detection.
Abstract
The effect of steam thermotherapy on Botrytis spp. populations in strawberry transplants was evaluated. Tray plants rooted in 0.2 L peat plugs of seasonal flowering cvs. Falco, Sonsation, and Soprano, and everbearing cvs. Favori and Murano were pre-treated with steam at 37 °C for 1 h, followed by 1 h at ambient temperature and air humidity, and then 2 or 4 h steam treatment at 44 °C. Except for one cultivar with a slight reduction in yield, there were no negative effects on plant performance. Compared to untreated transplants, mean incidence of Botrytis on the five cultivars was reduced by 43 and 86% with the 2 and 4 h treatments, respectively. Within cultivars the reduction was significant in 2 and 3 experiments following the 2 and 4 h treatments, respectively. Sclerotia from four different isolates of Botrytis were subjected to treatment including 4 h of steam thermotherapy and subsequently tested for viability. Following 14 days of incubation, 90 to 100% (mean 97%) of treated sclerotia failed to produce mycelial growth compared with untreated sclerotia, which all germinated and produced mycelia. Botrytis isolates recovered from both treated and untreated strawberry transplants were tested for resistance to seven fungicides, including boscalid, fenhexamid, fludioxonil, fluopyram, pyraclostrobin, pyrimethanil and thiophanate-methyl. Multiple fungicide resistance was common; 35.5% of isolates were resistant to fungicides from at least three FRAC groups. Results indicate that steam thermotherapy treatment strongly reduces populations of Botrytis spp., including fungicide-resistant strains, in strawberry transplants with negligible negative impacts on the transplants.
Authors
Arne Stensvand Katherine Ann Gredvig Nielsen May Bente Brurberg Vinh Hong Le Henrik Tellevik Stine Huseby Rune Vereide Lill-Iren Hansen Dag RøenAbstract
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Authors
Britt Puidet Romain Mabon Michele Guibert Riinu Kiiker Liina Soonvald Vinh Hong Le Håvard Eikemo Pauline Dewaegeneire Guillaume Saubeau Catherine Chatot Frederique Aurousseau David E. L. Cooke Alison K. Lees Isaac K. Abuley Jens G. Hansen Roselyne Corbiere Melen Leclerc Didier AndrivonAbstract
Until recently, genotypes of Phytophthora infestans were regionally distributed in Europe, with populations in western Europe being dominated by clonal lineages and those in northern Europe being genetically diverse because of frequent sexual reproduction. However, since 2013 a new clonal lineage (EU_41_A2) has successfully established itself and expanded in the sexually recombining P. infestans populations of northern Europe. The objective of this study was to study phenotypic traits of the new clonal lineage of P. infestans, which may explain its successful establishment and expansion within sexually recombining populations. Fungicide sensitivity, aggressiveness, and virulence profiles of isolates of EU_41_A2 were analyzed and compared with those of the local sexual populations from Denmark, Norway, and Estonia. None of the phenotypic data obtained from the isolates collected from Denmark, Estonia, and Norway independently explained the invasive success of EU_41_A2 within sexual Nordic populations. Therefore, we hypothesize that the expansion of this new genotype could result from a combination of fitness traits and more favorable environmental conditions that have emerged in response to climate change.
Abstract
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Abstract
In this study, we investigated if a steam treatment program used to produce disease-free strawberry transplants has the potential to also eliminate strawberry mite (Phytonemus pallidus) and two-spotted spider mite (Tetranychus urticae). Crowns of strawberry plants collected in a commercial field, containing young, folded leaves with all life stages of P. pallidus, and strawberry leaf discs on water agar with T. urticae with non-diapausing adult females and eggs from a laboratory rearing, were exposed to warm aerated steam in a steam cabinet in a series of four experimental runs over 2 years. The steam treatments constituted of a 1-h pre-treatment with 37 °C steam followed by a 1-h recovery period at 21–25 °C, and then a main steam treatment at 44 °C for either 2, 4 (both P. pallidus and T. urticae) or 6 h (the more heat tolerant T. urticae only). After steaming, the plant material with P. pallidus or T. urticae were incubated at 21–25 °C until survival was assessed after 1–6 days, depending on the mite species and life-stage. Non-steamed plant material with mites was used as controls. The 4-h treatment killed all P. pallidus eggs, larvae and adults, and the 2-h treatment killed all individuals in all three stages except for one egg in one of the runs. There were no or minor effects of the steam treatments on T. urticae adult and egg survival. Based on these results, the tested steam treatments may be used to eliminate the strawberry mite but not the two-spotted spider mite from strawberry planting material.
Abstract
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Abstract
Late blight caused by Phytophthora infestans is a serious, worldwide disease on potato (Solanum tuberosum). Phytophthora infestans normally reproduces in a clonal manner, but in some areas, as the Nordic Countries, sexual reproduction has become the major determinant of the population structure. To improve the late blight forecasting in Norway, the process-based Nærstad model was developed. The model includes the structure of the underlying processes in the disease development, including spore production, spore release, spore survival and infection of P. infestans. It needs hourly weather records of air temperature, precipitation, relative humidity, leaf wetness and global radiation. The model contained 19 uncertain parameters, and from a sensitivity analysis, 12 were detected as weakly sensitive to model outputs and fixed to a nominal value within their prior boundaries. The remaining seven parameters were detected as more sensitive to model outputs and were parameterized using maximum a'posteriori (MAP) estimates, calculated through Bayesian calibration. The model was developed based on literature combined with field data of daily observed number of lesions on trap plants of the Bintje cultivar (late blight susceptible) at Ås during the seasons 2006-2008 and 2010-2011. It was further tested on daily observed number of lesions on trap plants of the cultivars Bintje, Saturna (medium susceptible) and Peik (medium resistant) at Ås during the seasons 2012-2015. For all three cultivars, the Nærstad model improved with a higher model accuracy compared to the existing HOSPO-model and the Førsund rules that both have shown relatively good correlation with blight development in field evaluations in Norway. The best accuracy was found for Bintje (0.83) closely followed by Saturna (0.79), whereas a much lower accuracy was detected for Peik (0.66).
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Authors
Claudio Dias Jr. Da Silva Vinh Hong Le Belachew Asalf Tadesse Chloé Grieu Nan-Yi Wang Natalia A. Peres William Turechek Arne StensvandAbstract
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Authors
Claudio Dias Jr. Da Silva Vinh Hong Le Belachew Asalf Tadesse Chloé Grieu Nan-Yi Wang Natalia A. Peres William Turechek Arne StensvandAbstract
No abstract has been registered
Authors
Simeon Rossmann Merete Wiken Dees Torfinn Torp Vinh Hong Le Monica Skogen Borghild Glorvigen Jan van der Wolf May Bente BrurbergAbstract
Potato soft rot Pectobacteriaceae (SRP) cause large yield losses and are persistent in seed lots once established. In Norway, different Pectobacterium species are the predominant cause of soft rot and blackleg disease. This work aimed to evaluate the potential of real-time PCR for quantification of SRP in seed tubers, as well as investigating the status of potato seed health with respect to SRP in Norway. A total of 34 seed potato lots, including certified seeds, was grown and monitored over three consecutive years. All seed lots contained a quantifiable amount of SRP after enrichment, with very few subsamples being free of the pathogens. A high SRP prevalence based on a qPCR assay, as well as a high symptom incidence in certified seeds were observed, suggesting that current criteria for seed certification are insufficient to determine tuber health and predict field outcomes. Pectobacterium atrosepticum was the most abundant species in the examined seed lots and present in all lots. Consistently good performance of first generation seed lots with respect to blackleg and soft rot incidence, as well as low quantity of SRP in these seed lots demonstrated the importance of clean seed potatoes. Weather conditions during the growing season seemed to govern disease incidence and SRP prevalence more than seed grade. The impact of temperature, potato cultivar and Pectobacterium species on tuber soft rot development were further examined in tuber infection experiments, which showed that temperature was the most important factor in nearly all cultivars. Large-scale quantification of latent infection and predictive models that include contributing factors like weather, infecting bacterial species and cultivar are needed to reduce soft rot and blackleg.
Authors
Merete Wiken Dees Simeon Rossmann Monica Skogen Vinh Hong Le Arnaud Lefrancois Abdelhameed Elameen Borghild Glorvigen Alison K. Lees Jan van der Wolf May Bente BrurbergAbstract
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Authors
Pia Heltoft Thomsen May Bente Brurberg Monica Skogen Vinh Hong Le Jafar Razzaghian Arne HermansenAbstract
The prevalence of Fusarium dry rot in potatoes produced in Norway was investigated in a survey for three consecutive years in the period 2010 to 2012. A total of 238 samples (comprising 23,800 tubers) were collected, representing different cultivars and production regions in Norway. Fusarium spp. were detected in 47% of the samples, with one to three species per sample. In total, 718 isolates of Fusarium spp. were recovered and identified to seven species. The most commonly isolated species was Fusarium coeruleum, comprising 59.6% of the total Fusarium isolates and found in 17.2% of the collected samples, followed by Fusarium avenaceum (27.2% of the isolates and found in 27.7% of the samples). Fusarium sambucinum was the third most prevalent species (6.4% in 8.8% of the samples) and Fusarium culmorum the fourth (5.2% in 6.3% of the samples). Less prevalent species included Fusarium cerealis, Fusarium graminearum, and Fusarium equiseti (<1% in 0.4 to 1.3% of the samples). F. coeruleum was the most prevalent species in northern and southwestern Norway, whereas F. avenaceum was dominating in eastern Norway. The potato cultivars Berber and Rutt were susceptible to all Fusarium spp. A new TaqMan real-time PCR assay specific for F. coeruleum was developed, which successfully identified Norwegian isolates. This and other previously developed real-time PCR assays targeting different Fusarium species were evaluated for their ability to detect latent infections in potatoes at harvest. This study provides new information on the current occurrence of different Fusarium species causing Fusarium dry rot in potatoes in Europe including areas far into the arctic in the north of Norway.
Authors
Ingerd Skow Hofgaard Till Seehusen Heidi Udnes Aamot Hugh Riley Jafar Razzaghian Vinh Hong Le Anne-Grete Roer Hjelkrem Ruth Dill-Macky Guro BrodalAbstract
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Authors
Ingerd Skow Hofgaard Till Seehusen Heidi Udnes Aamot Jafar Razzaghian Vinh Hong Le Hugh Riley Børge Holen Elisa Gauslaa Hege Særvold Steen Anne-Grete Roer Hjelkrem S.G. Edwards Ruth Dill-Macky Guro BrodalAbstract
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Authors
Ingerd Skow Hofgaard Till Seehusen Heidi Udnes Aamot Unni Abrahamsen Jafar Razzaghian Vinh Hong Le Hugh Riley Einar Strand Elisa Gauslaa Mauritz Åssveen May Bente Brurberg Hege Særvold Steen Guro BrodalAbstract
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Authors
Ingerd Skow Hofgaard Till Seehusen Heidi Udnes Aamot Unni Abrahamsen Jafar Razzaghian Vinh Hong Le Hugh Riley Einar Strand Elisa Gauslaa Mauritz Åssveen May Bente Brurberg Hege Særvold Steen Guro BrodalAbstract
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Authors
Ragnhild Nærstad SS. Sharma Vinh Hong Le Abdelhameed Elameen Arne Hermansen May Bente BrurbergAbstract
Initial sources of inoculum of Phytophthora infestans were investigated in ten potato fields with early outbreaks of potato late blight. Infected plant samples and isolates from these fields were examined with respect to mating type prevalence, fungicide resistance and genotypes based on microsatellites A high proportion (91 %) of the isolates recovered were of mating type A1. However, both mating types were found in 3 of 9 fields with more than one isolate recovered, and sometimes both mating types were found on the same plant. Most of the isolates recovered from fields treated with metalaxyl-M prior to sampling had reduced sensitivity or were resistant to metalaxyl-M, and most of the isolates recovered form fields without metalaxyl treatment were sensitive. The isolates recovered from fields treated with propamocarb prior to sampling had a higher frequency of reduced sensitivity to propamocarb than isolates from fields without propamocarb treatment. We found that most plants contained more than one P. infestans SSR-genotype. Clustering analysis of the infected samples revealed that most samples clustered together according to fields. By combining information from P. infestans isolates and DNA extracts from the leaf lesions we found examples of both mating type A1 and A2 having the same multilocus genotype. This result indicates that both of these genotypes have a common ancestor, hence the inoculum originates from oospores. Although this a minor study of only 10 fields with a limited amount of isolates and plant samples, the results indicate oospores in the soil is an inoculum source. Hence the forecasting model to predict outbreaks of potato late blight should be modified to include this.
Authors
May Bente Brurberg Mads Sønderkær Monica Skogen Even Sannes Riiser Vinh Hong Le Merete Dees Kåre Lehman NielsenAbstract
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Authors
Merete Dees Mads Sønderkær Monica Skogen Even Sannes Riiser Vinh Hong Le Kåre Lehman Nielsen May Bente BrurbergAbstract
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Authors
Ingerd Skow Hofgaard Till Seehusen Heidi Udnes Aamot Unni Abrahamsen Jafar Razzaghian Vinh Hong Le Hugh Riley Einar Strand Børge Holen Elisa Gauslaa Tove Kristina Sundgren Mauritz Åssveen Berit Nordskog Hege Særvold Steen Guro BrodalAbstract
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Authors
Merete Dees Mads Sønderkær Monica Skogen Even Sannes Riiser Vinh Hong Le Kåre Lehman Nielsen May Bente BrurbergAbstract
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A survey of the prevalence of skin blemish diseases in potatoes after the growing seasons of 2008 and 2009 was carried out on 247 potato lots representing different cultivars and production regions in Norway. The results showed the presence of silver scurf (Helminthosporium solani) in all lots. Skin spot (Polyscytalum pustulans) and black scurf (Rhizoctonia solani) were found in 80% of the lots, and black dot (Colletotrichum coccodes) and common scab caused by Streptomyces spp. were present in 50–70%. Also, powdery scab (Spongospora subterranea) occurred in 65–80% of the lots, and root-lesion nematodes (Pratylenchus spp.) were detected in 60% of the sub-samples that exhibited symptoms of common scab.
Authors
Ragnhild Nærstad Arne Hermansen Vinh Hong Le Grete Lund Abdelhameed Elameen May Bente BrurbergAbstract
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Authors
May Bente Brurberg Abdelhameed Elameen Vinh Hong Le Ragnhild Nærstad Arne Hermansen Ari Lehtinen Asko Hannukkala Bent Nielsen Jens Hansen Björn Andersson Jonoathan YuenAbstract
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Authors
Merete Wiken Dees Arild Sletten Ricardo Holgado Eldrid Lein Molteberg Tor J. Johansen May Bente Brurberg Vinh Hong Le Ragnhild Nærstad Arne HermansenAbstract
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Authors
May Bente Brurberg Abdelhameed Elameen Vinh Hong Le Ragnhild Nærstad Arne Hermansen Ari Lehtinen Asko Hannukkala Bent Nielsen Jens Hansen Björn Andersson Jonathan YuenAbstract
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Authors
A. Lehtinen B. Andersson Vinh Hong Le Ragnhild Nærstad M. Rastas E. Ketoja A. O. Hannukkala Arne Hermansen B. Nielsen J. G. Hansen J. YuenAbstract
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Authors
A. Lehtinen A. Hannukkala B. Andersson Arne Hermansen Vinh Hong Le Ragnhild Nærstad May Bente Brurberg B.J. Nielsen J. G. Hansen J. YuenAbstract
No abstract has been registered