Annette Anda

Førstesekretær

(+47) 404 95 116
annette.anda@nibio.no

Sted
Særheim

Besøksadresse
Postvegen 213, NO-4353 Klepp stasjon

Sammendrag

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.

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Sammendrag

A glasshouse experiment was carried out with the aim of quantifying the relative contribution of seed- and soil-borne inoculum of three Fusarium spp. (F. coeruleum, F. sambucinum and F. avenaceum) in causing dry rot in two potato cultivars, Asterix and Saturna. Different concentrations of inoculum; control (water only), low (102 conidia ml−1) and high (105 conidia ml−1) were used to inoculate seed and infest soil and disease severity on progeny tubers was subsequently assessed following an 8-week post-harvest storage period. Overall, F. sambucinum caused significantly (P < 0.05) larger rots than F. avenaceum, with the severity of rots caused by F. coeruleum being intermediate, and disease severity was greater in cv. Asterix than cv. Saturna (P < 0.01). None of the seed inoculation treatments resulted in dry rot development on progeny tubers. In contrast, soil infested with Fusarium species resulted in significantly more severe tuber rots on progeny tubers compared with controls (P < 0.01). Soil infested with F. sambucinum (low and high levels) resulted in significantly more severe rots than control treatments (P < 0.001), whilst only high levels of F. avenaceum soil inoculum increased the severity of tuber rots compared with control treatments (P < 0.05). Increased disease severity observed as a result of the addition of inoculum of F. coeruleum to soil was not significant.

Sammendrag

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.

Sammendrag

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.

Sammendrag

Bioforsk had the pleasure of hosting the Nordic Baltic Potato Tuber-Disease Workshop 2011 (PTDW 2011) at Hamar, Norway 16-18 November 2011. The workshop was mainly aimed at potato advisors, including the potato industry, and scientists from the Nordic and Baltic countries. In addition, we also had participants that are plant breeders, students, and and other people interested in potato quality. In total there were about 60 participants at the workshop from the Nordic countries, UK, Switzerland, USA and China. This Workshop was an activity in Bioforsk project: “Improved potato quality by reduced skin blemish diseases (scab and scurf) in Norwegian potato production” (2008-2012). This project was financed by grants from the Research Council of Norway, the Foundation for Research Levy on Agricultural Products, the Agricultural Agreement Research Fund, and Norwegian potato growers and food industries; Gartnerhallen, Bama, ICA-Norge, NF-Grønt, KiMs and Maarud. The foreign experts attached to this project, Alison Lees (UK), Leslie Wanner (USA) and Jari Valkonen (Finland), were contributors in the workshop. In addition invited speakers were Lv Dianqiu from China and Ueli Merz from Switzerland. The workshop had 5 different sections, in which the 3 first had presentations from the project: 1. Occurrence of skin blemish diseases in the Nordic and Baltic countries 2. Diagnosis and biology of different skin blemish pathogens 3. Control of skin blemish diseases 4. Research activities on other potato tuber diseases in Nordic and Baltic countries 5. Future challenges In the table of contents, the abstracts are presented in the same order as found in the program. The scientific workshop committee consisted of Jari Valkonen (Finland), Björn Andersson (Sweden), Bent J. Nielsen (Denmark) and Arne Hermansen (Norway).

Sammendrag

En forbedret tørråtevarslingsmodell er utviklet basert på forsøk med sporefelle og fangstplanter. Modellen beregner risikoen for sporeproduksjon med påfølgende sporespredning, overlevelse og infeksjon ut fra klimadata på timebasis, forutsatt at det er tørråtesmitte i området.

Sammendrag

Fungicidresistens har fått økt aktualitet på grunn av tilgang på relativt få fungicider i flere kulturer. I tillegg har flere av de nyere fungicidene et iboende potensial for at skadegjørerne lett kan utvikle resistens overfor disse. Kartlegging av problemene og riktige bekjempelsesstrategier er nødvendig.

Sammendrag

Potettørråte ble i 2006 et langt større problem for mange dyrkere på Østlandet enn det en kunne forvente ut fra klima i juli. Feltforsøk i ulike områder av landet viste at både sprøyting etter ulike varsler og ved faste intervall med dynamiske doser er aktuelle strategier.

Sammendrag

I to års forsøk med beising av settepoteter med ulik smittegrad av svartskurvsoppen har beising bare ført til litt raskere spiring, og ingen sikre effekter på avlingsmengde og tørrstoff. Settepoteter med lavt smittenivå av svartskurv spirte raskest. Mengden svartskurv-sklerotier på knollene ble litt redusert ved beising, men frekvens av knoller med svartskurv-sklerotier ble ikke redusert. Det ble ikke sikre forskjeller i virkning av beisemidlene eller påføringsmetodene på avling eller kvalitet.

Sammendrag

Forebyggende tiltak mot salatbladskimmel bør følges hele sesongen, mens kjemiske tiltak er aktuelle når værforholdene er gunstige for infeksjon og det er fare for smitte. Det har vist seg å være svært varierende når og hvor første angrep av salatbladskimmel oppstår. Overvåk derfor feltene nøye og sett i gang tiltak allerede ved begynnende svake angrep.

Sammendrag

Bladskimmel er et av de viktigste problemene i produksjonen av mange grønnsakskulturer på friland. Gunstige forhold for spredning og utvikling av bladskimmel kan varsles, og dermed bidra til å optimalisere bruken av fungicider mot denne sjukdommen.