Sammendrag

The plant pathogenic fungus Fusarium langsethiae produces the highly potent mycotoxins HT-2 and T-2. Since these toxins are frequently detected at high levels in oat grain lots, they pose a considerable risk for food and feed safety in Norway, as well as in other north European countries. To reduce the risk of HT-2/T- 2-contaminated grain lots to enter the food and feed chain, it is important to identify factors that influence F. langsethiae infection and mycotoxin development in oats. However, the epidemiology of F. langsethiae is unclear. A three-year survey was performed to reveal more of the life cycle of F. langsethiae and its interactions with oats, other Fusarium species, as well as insects, mites and weeds. We searched for inoculum sources by quantifying the amount of F. langsethiae DNA in crop residues, weeds, and soil sampled from a selection of oat-fields. To be able to define the onset of infection, we analysed the amount of F. langsethiae DNA in oat plant material sampled at selected growth stages (between booting and maturation), as well as the amount of F. langsethiae DNA and HT-2 and T-2 toxins in the mature grain. We also studied the presence of possible insect- and mite vectors sampled at the selected growth stages using Berlese funnel traps. The different types of materials were also analysed for the presence F. graminearum DNA, the most important deoxynivalenol producer observed in Norwegian cereals, and which presence has shown a striking lack of correlation with the presence of F. langsethiae in oat. Results show that F. langsethiae DNA may occur in the oat plant already before heading and flowering. Some F. langsethiae DNA was observed in crop residues and weeds, though at relatively low levels. No Fusarium DNA was detected in soil samples. Of the arthropods that were associated with the collected oat plants, aphids and thrips species were dominating. Further details will be given at the meeting.

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.

Sammendrag

The plant pathogenic fungus Fusarium langsethiae produces the highly potent mycotoxins HT-2 and T-2. Since these toxins are frequently detected at high levels in oat grain lots, they pose a considerable risk for food and feed safety in Norway, as well as in other north European countries. To reduce the risk of HT-2/T- 2-contaminated grain lots to enter the food and feed chain, it is important to identify factors that influence F. langsethiae infection and mycotoxin development in oats. However, the epidemiology of F. langsethiae is unclear. A three-year survey was performed to reveal more of the life cycle of F. langsethiae and its interactions with oats, other Fusarium species, as well as insects, mites and weeds. We searched for inoculum sources by quantifying the amount of F. langsethiae DNA in weeds, crop residues, and soil, sampled from a predetermined selection of oat-fields. To be able to define the onset of infection, we analysed the amount of F. langsethiae DNA in oat plant material sampled at selected growth stages (between booting and maturation), as well as the amount of F. langsethiae DNA and HT-2 and T-2 toxins in the mature grain. We also studied the presence of possible insect- and mite vectors sampled at the selected growth stages using Berlese funnel traps. All the different types of materials were also analysed for the presence F. graminearum DNA, the most important deoxynivalenol producer observed in Norwegian cereals, and which presence has shown a striking lack of correlation with the presence F. langsethiae in oat. Preliminary results show that F. langsethiae DNA may occur in the oat plant before heading and flowering. Some F. langsethiae DNA was observed in crop residues and weeds, though at relatively low levels. More results from this work will be presented at the meeting.

Sammendrag

The plant pathogenic fungus Fusarium langsethiae produces the highly potent mycotoxins HT-2 and T-2. Since these toxins are frequently detected at high levels in oat grain lots, they pose a considerable risk for food and feed safety in Norway, as well as in other north European countries. To reduce the risk of HT-2/T- 2-contaminated grain lots to enter the food and feed chain, it is important to identify factors that influence F. langsethiae infection and mycotoxin development in oats. However, the epidemiology of F. langsethiae is unclear. A three-year survey was performed to reveal more of the life cycle of F. langsethiae and its interactions with oats, other Fusarium species, as well as insects, mites and weeds. We searched for inoculum sources by quantifying the amount of F. langsethiae DNA in weeds, crop residues, and soil, sampled from a predetermined selection of oat-fields. To be able to define the onset of infection, we analysed the amount of F. langsethiae DNA in oat plant material sampled at selected growth stages (between booting and maturation), as well as the amount of F. langsethiae DNA and HT-2 and T-2 toxins in the mature grain. We also studied the presence of possible insect- and mite vectors sampled at the selected growth stages using Berlese funnel traps. All the different types of materials were also analysed for the presence F. graminearum DNA, the most important deoxynivalenol producer observed in Norwegian cereals, and which presence has shown a striking lack of correlation with the presence F. langsethiae in oat. Preliminary results show that F. langsethiae DNA may occur in the oat plant before heading and flowering. Some F. langsethiae DNA was observed in crop residues and weeds, though at relatively low levels. More results from this work will be presented at the meeting.

Sammendrag

Forsøksresultatene som presenteres i denne rapporten er biologisk godkjenningsprøving av soppmidler utført på oppdrag fra Mattilsynet i 2014. Inkludert i rapporten er også forsøk eller egne forsøksledd som grupperes som biologisk utviklingsprøving. Forsøkene er utført etter GEP-kvalitet1 hvis ikke annet er nevnt. Dette innebærer at det er utarbeidet skriftlige prosedyrer for nesten alle arbeidsprosesser. Disse prosedyrene, kalt standardforskrifter (SF’er), er samlet i en kvalitetshåndbok. Denne er delt ut til alle personer som arbeider med utprøving av plantevernmidler. De samme personene har også vært med på et endagskurs i GEP-arbeid.

Sammendrag

Forsøksresultatene som presenteres i denne rapporten er biologisk godkjenningsprøving av soppmidler utført på oppdrag fra Mattilsynet i 2012. Inkludert i rapporten er også forsøk eller egne forsøksledd som grupperes som biologisk utviklingsprøving. Forsøkene er utført etter GEP-kvalitet1 hvis ikke annet er nevnt. Dette innebærer at det er utarbeidet skriftlige prosedyrer for nesten alle arbeidsprosesser. Disse prosedyrene, kalt standardforskrifter (SF’er), er samlet i en kvalitetshåndbok. Denne er delt ut til alle personer som arbeider med utprøving av plantevernmidler. De samme personene har også vært med på et endagskurs i GEP-arbeid.

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Sammendrag

Fusarium langsethiae is a recently characterized fungus within the genus Fusarium. It is found as a grain contaminant of small grain cereals such as oats and barley, and to a lesser extent wheat. Fusarium langsethiae is particularly widespread in the Nordic countries and the UK where it poses a serious problem as the main producer of T-2 and HT-2 mycotoxins. The biology of F. langsethiae and its interaction with the plant remains poorly understood, partly hampered by difficulties reproducing a natural level of infection under controlled conditions. The reported study was designed as a series of glasshouse experiments to advance our understanding of F. langsethiae biology by investigating alternative infection routes and its proliferation in oats, Avena sativa. Various methods of seed, soil, and seedling inoculation, boot injection and spray inoculation, were tested. The results clearly show a strong preference of F. langsethiae for the panicle, ruling out alternative infection routes. At relatively low temperatures spray infection, accompanied by prolonged humidity, ensured a thorough establishment of the fungus both at flowering and at early dough stage. Boot injection proved to be a reliable working tool for production of an even and predictable grain infection. Apart from in the panicle, considerable fungal proliferation was only detected in flag leaf nodes, and was a direct consequence of the boot injection method. Fungal presence in the node tissue also correlated with significant stunting of infected shoots. In light of the results the pathogenic and endophytic abilities of F. langsethiae are discussed.

Sammendrag

Moderat auka av frie koparion i næringsløysinga er kjent å kunna redusera spreiing av pseudosoppar som Pythium og Phytophthora. Effekten på Fusarium er meir usikker. Laboratorieforsøk gjennomført i prosjektet  "Redusert åtak av rotsjukdomar i norske prydplanter" viser at konsentrasjon av frie koparion må aukast til  relativt høge nivå for å hindra sporespiring hos Fusarium foetens.

Sammendrag

Bladfall og daude skot har dei siste tiåra vorte eit omfattande problem i villbestand av kristtorn (Ilex aquifolium) langs sørvest-kysten av Noreg. Fleire soppar vert ofte isolert i samband med skadane, men spesielt ein Fusarium-art, som ved DNA-analyse synte seg å vera mest lik F. acuminatum, dominerar.

Sammendrag

Grønne blade og smukke, røde bær om vinteren gør kristtorn (Ilex aquifolium) velegnet til juledekorationer. Bladfald og døde skud er i de sidste ti år blevet et omfattende problem i vilde bestande af kristtorn langs sydvestkysten af Norge. Flere svampe er blevet isoleret i forbindelse med skaderne, men især en Fusarium acuminatum-lignende art dominerer.

Sammendrag

Grøne blad og raude bær gjer frisk kristtorn til eit vakkert syn utover hausten og vinteren (Figur 1). Kristtorn er viltveksande frå Aust-Agder til Nordmøre, og særleg i Rogaland og Sunnhordland er kristtorn vanleg. I prosjektet "Betre skjøtsel av viltveksande kristtorn som grunnlag for betre plantekvalitet og større utbyte", finansiert av Norsk Genressurssenter, vart det i 2006 sett i gang eit forsøk med beiting av sau og betre stell i eit villbestand av kristtorn (Ilex aquifolium) i Rogaland. Bakgrunnen for dette var at bladfall og daude skot har vorte eit omfattande problem dei siste tiåra. Problemet ser ut til å ha auka i takt med gjengroinga av kulturlandskapet. Ein Fusarium-art, som ved DNA-analyse synte seg å vera mest lik F. acuminatum, ser ut til å vera hovudårsaka til skaden. Topping, tynning og oppstamming av kristtorn, rydding av buskar og kratt og beiting med sau over ein periode på fire år har gitt langt mindre sjukdom og betre kvalitet på kristtornen og auka salsverdien monaleg.

Sammendrag

I prosjektet "Betre skjøtsel av viltveksande kristtorn som grunnlag for betre plantekvalitet og større utbyte", finansiert av Norsk Genressurssenter, vart det i 2006 sett i gang eit forsøk med beiting av sau og betre stell i eit villbestand av kristtorn i Rogaland. Bakgrunnen for dette var at bladfall og daude skot har vorte eit omfattande problem dei siste tiåra. Problemet ser ut til å ha auka i takt med gjengroinga av kulturlandskapet. Ein Fusarium-art, som ved DNA-analyse synte seg å vera mest lik F. acuminatum, ser ut til å vera hovudårsaka til skaden. Topping, tynning og oppstamming av kristtorn, rydding av buskar og kratt og beiting med sau over ein periode på fire år har gitt langt mindre sjukdom og betre kvalitet på kristtornen og auka salsverdien monaleg.

Sammendrag

Bladfall og daude skot har dei siste tiåra vorte eit omfattande problem i villbestand av kristtorn (Ilex aquifolium) langs sørvest kysten av Noreg. Fleire soppar vert ofte isolert i samband med skadane, men spesielt ein Fusarium-art, som ved DNA analyse synte seg å vera mest lik F. acuminatum, dominerar. Ved eit tilfelle vart den same Fusarium-arten funnen på daude skot på ei nordmannsedelgran (Abies nordmanniana). Soppangrepa på kristtorn er truleg eit resultat av aukande gjengroing på grunn av mindre beiting no enn tidlegare.

Sammendrag

I to veksthusforsøk ble hvete og havre sprayinokulert under blomstring med en enkelt eller en blanding av flere Fusarium arter. De artene som ble studert var F. graminearum, F. culmorum, F. avenaceum, F. poae og F. langsethiae. Vi studerte i hvilken grad samspillet mellom artene påvirket etableringen og veksten av Fusarium, og også hvilken effekt dette hadde på mykotoksinproduksjonen.

Sammendrag

I to veksthusforsøk ble hvete og havre sprayinokulert under blomstring med en enkelt eller en blanding av flere Fusarium arter. De artene som ble studert var F. graminearum, F. culmorum, F. avenaceum, F. poae og F. langsethiae. Vi studerte i hvilken grad samspillet mellom artene påvirket etableringen og veksten av Fusarium, og også hvilken effekt dette hadde på mykotoksinproduksjonen.

Sammendrag

Fusarium head blight (FHB) is a widespread and destructive disease of cereals caused by a number of Fusarium species. Under field conditions a mixture of Fusarium species exists. While FHB in wheat has been well studied, Fusarium infection of oats has not yet been characterized. Little is known about how the presence of a mixture of different Fusarium species in the same sample affects the mycotoxin production. During flowering plants of wheat and oats grown under greenhouse conditions were spray inoculated with single and multiple Fusarium species (F. graminearum, F. culmorum, F. avenaceum, F. poae and F. langsethiae). Chemical toxin analysis of harvested grain showed that the content of mycotoxins in oat were generally lower than in corresponding wheat samples. Neither T-2 nor HT-2 was detected in wheat or oat. Neither was it possible to detect F. langsethiae in the kernels when analysed by real-time TaqMan PCR. All wheat samples inoculated with F. graminearum contained relative high levels of deoxynivalenol. Samples infected with F. culmorum contained nivalenol in addition to deoxynivalenol. Moniliformin was detected at levels below the quantification limit in one third of the samples. The inoculation experiment was repeated with an adjusted inoculation procedure for F. langsethiae and F. poae, resulting in good establishment of all Fusarium species. The amounts of the different Fusarium species and the level of the corresponding mycotoxins were determined. The interactions between the Fusarium species regarding establishment on the fungus on the developing kernels and the production of the mycotoxins, will be discussed.

Sammendrag

Fusarium head blight (FHB) is a widespread and destructive disease of cereals caused by a number of Fusarium species. Under field conditions a mixture of Fusarium species exists. While FHB in wheat has been well studied, Fusarium infection of oats has not yet been characterized. Little is known about how the presence of a mixture of different Fusarium species in the same sample affects the mycotoxin production. During flowering plants of wheat and oats grown under greenhouse conditions were spray inoculated with single and multiple Fusarium species (F. graminearum, F. culmorum, F. avenaceum, F. poae and F. langsethiae). Chemical toxin analysis of harvested grain showed that the content of mycotoxins in oat were generally lower than in corresponding wheat samples. Neither T-2 nor HT-2 was detected in wheat or oat. Neither was it possible to detect F. langsethiae in the kernels when analysed by real-time TaqMan PCR. All wheat samples inoculated with F. graminearum contained relative high levels of deoxynivalenol. Samples infected with F. culmorum contained nivalenol in addition to deoxynivalenol. Moniliformin was detected at levels below the quantification limit in one third of the samples. The inoculation experiment was repeated with an adjusted inoculation procedure for F. langsethiae and F. poae, resulting in good establishment of all Fusarium species. The amounts of the different Fusarium species and the level of the corresponding mycotoxins were determined. The interactions between the Fusarium species regarding establishment on the fungus on the developing kernels and the production of the mycotoxins, was discussed.

Sammendrag

In April 2007, orange-red pustules were found in needle scars on defoliated, dead shoots on a nordmann fir (Abies nordmanniana) Christmas tree in Rogaland County in south western Norway. A microscope slide made from the pustules revealed Fusarium-macrospores. On average they were 40.2 µm long and 2.9 µm wide (n=50). No microspores were found. A red coloured culture was obtained by transferring spore mass from a sporodochium to PDA (potato dextrose agar) with a sterile needle. The culture was transferred to SNA (spezieller nährstoffarmer agar) where macrospores developed. The majority of the spores had three septa, most of them were slightly curved, apically bent, basal cells were foot shaped, and spores were long and slender. Six singlespore cultures appeared identical on SNA. Two were chosen for an inoculation test. This test took place on 4 June 2007 in a polyethylene tunnel where the plants were kept during the whole experimental period. Nearly fully grown current year shoots on container grown nordmann fir transplants were inoculated by placing PDA agar plugs with fungal growth at the base of some unwounded needles on each shoot. Twelve transplants were used for each of the two isolates. The plants were covered with polyethylene bags for five days. After the bags were removed, the foliage was kept wet throughout the growing season by 1-3 minutes (depending on temperature) overhead irrigation every third hour. Brown shoots developed during the summer regardless of which singlespore isolate that had been used for inoculation. Samples from brown shoots were collected 20 October. No sporodochia, like we found under field conditions in April, had developed on the inoculated shoots. Neither did they develop after incubation in the laboratory. Only a whitish, fluffy mycelium was seen. CZID (Czapek dox iprodione dichloran agar) was used for reisolation from the dead shoots. From each group of 12 inoculated plants, two and three Fusarium-cultures were obtained, respectively. No symptoms were observed and no Fusarium sp. was isolated from the control plants (exposed to same treatment, but agar plugs with no fungal growth had been used). The Fusarium strain could not be accurately identified to species when the FUSARIUM-ID database v. 1.0 (http://fusarium.cbio.psu.edu) was searched with partial sequence of TEF (translation elongation factor 1-"). The original culture plus the two single spore cultures used for inoculation had identical TEF sequences which were most similar to F. acuminatum (97% identity). One out of six single spore cultures from each of the five reisolates, was sequenced. One of them matched the original culture, but the other four were most similar to F. avenaceum (98% identity). Different from the original culture, the F. av.-like isolates had both macro- and microconidia (0-3 septa, oval spore shape). On PDA, the F. ac.-like culture grew 25 mm in 72 hours (dark and 25°C) and the four F. av.-like cultures grew between 32 to 40 mm. They could not be distinguished by colour. Hyphal coils were found on both species, but were most prominent on the F. ac.-like culture. The fact that sequencing revealed involvement of two Fusarium-species, makes is difficult to draw conclusions about pathogenicity, but since the control plants showed no symptoms, there may be indications that the F. ac.-like fungus killed the inoculated shoots and that the F. av.-like fungus came in as a secondary invader from the environment inside or outside the tunnel. F. acuminatum is reported as a pathogen on conifer seeds and seedlings, but to our knowledge this is the first report of a F. ac.-like fungus causing dieback on a Christmas tree.

Sammendrag

Karnal bunt er en karanteneskadegjører som forårsaker sotsykdom i hvetaks. Sykdommen er ikke etablert i Norge eller andre europeiske land, men finnes i land som vi importerer hvete ifra. Resultater fra et internasjonalt prosjekt viser at soppens sporer kan overleve i minst tre år i jord, inkludert under norske forhold, og at vanlige hvetesorter er mottagelige for sjukdommen.

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Sammendrag

Representative European wheat cultivars were tested under quarantine containment for their susceptibility to Tilletia indica, the cause of Karnal bunt of wheat. Fifteen winter and 15 spring wheat (Triticum aestivum) and 11 durum wheat (Triticum durum) cultivars were inoculated by boot injection just prior to ear emergence to test their physiological susceptibility. Selected cultivars were then re-tested by spray inoculation after ear emergence to determine their morphological susceptibility, which is a better predictor of field susceptibility. At maturity, the ears and seeds were assessed for incidence and severity of disease. For the physiological susceptibility tests, 13/15 winter wheat cultivars were infected and the percentage of infected seeds ranged from 1 to 32%. For spring cultivars, 13/15 cultivars were infected and the percentage of infected seeds ranged from 1 to 48%. For the durum cultivars, 9/11 were infected and the percentage of infected seeds ranged from 2 to 95%. Across all cultivars, 35/41 were infected. Based on historical Karnal bunt susceptibility categories using coefficients of infection, one cultivar was classed as highly susceptible, three as susceptible, 11 as moderately susceptible, 20 as resistant and only six as highly resistant. The spray-inoculation morphological susceptibility tests broadly confirmed the physiological susceptibility results, although lower levels of infection were observed. Overall, the range of susceptibility was similar to that found in cultivars grown in Karnal bunt affected countries. The results demonstrate that European wheat cultivars are susceptible to T. indica and thus could potentially support the establishment of T. indica if introduced into Europe.

Sammendrag

Experiments of the effect of haulm killing and different other treatments during end of season on tuber blight of potato were presented

Sammendrag

The effect of different end of season treatements of the haulm on tuber blight has beeen investigated in a five year project. Haulm killing reduced the amount of inoculum in the haulm and soil and the amount of tuber blight compared to harvest on green haulm treated with fungicide. The infectivity of the soil was reduced to about the half in three weeks and the infectivity persistes longer in dry soil than in wet soil. Most of the inoculum washed down from the haulm remaines in the top soil, at 15 mm precipitation in pot experiments.

Sammendrag

Genetic variation and pathogenicity of Phytophthora infestans isolates collected from organic potato crops of the susceptible cv. Bintje and the moderately resistant cv. Santé were assesed in France, Norway, and the United Kingdom in 2001 and in Switzerland in 2001 and 2002. Population structures differed considerably between the four P. infestans populations. Those from France, Switzerland and the UK were mainly clonal populations showing restricted levels of genetic diversity, whilst those from Norway were mixed A1 and A2 mating type populations with high levels of genetic diversity, suggesting periodical sexual reproduction. Isolates collected from cv. Bintje were on average more aggressive than or comparable to isolates from cv. Santé. Race complexity varied considerably between the regional P. infestans populations with isolates from France and Switzerland showing the highest number of virulence factors. In all pathogen samples but the French, isolates collected from cv. Santé were more complex than isolates collected from cv. Bintje. No directional selection towards increased aggressiveness towards the more resistant cultivar Santé was observed. This suggests that there is no shift towards increased level of pathogenicity in P. infestans populations following the large-scale introduction of more resistant potato varieties in organic production systems in Europe.

Sammendrag

Carrot roots with cavity spot lesions from 8 different counties in Norway were sampled and Pythium species were isolated on selective medium. Pythium spp. were characterised morphologically and by species-specific PCR. Laboratory experiments with inoculations of carrot roots were performed. A total of 130 isolates out of 230 Pythium-like isolates tested with PCR were identified as pathogenic species of Pythium. These were P. intermedium (29 %), P. sulcatum (23 %), P. sylvaticum (16 %), P. violae (15 %) and a possible new Pythium species designated P. "vipa" (18 %). There were some difference between geographical regions and ages of cavities regarding the frequency of the different species isolated. When rating sunken lesions in the laboratory inoculation experiments, P. "vipa" was the most aggressive and P. violae the least aggressive species. P. intermedium and P. "vipa" caused more discolouration of the infected carrot tissue than the other species. The importance of the different Pythium spp. as agents of cavity spot in Norway is discussed.

Sammendrag

Resultater fra forsøkene viser at i vårhvete vil en behandling med en strobilurinblanding i perioden fra begynnende skyting til full skyting gi en god beskyttelse mot hveteaksprikk. To ganger behandling kan være aktuelt i sorter med liten mjøldoggresistens. I gjennomsnitt for feltene i vårhvete i 2003-2005 var økningen i lønnsomhet ved to ganger behandling beskjeden i forhold til en gang behandling. I 25 % av forsøkene i perioden var det ikke behov for behandling. Tre ganger behandling var ikke lønnsomt i forsøkene. I forsøkene i høsthvete hadde en tidlig behandling med Stereo god virkning mot mjøldogg og på oppsmitting av hveteaksprikk. En tidlig behandling med et "ikke strobilurin", etterfulgt av en redusert eller full dose av en strobilurinblanding avhengig av sjukdomsrisiko vil ofte være en god strategi i høsthvete. Riktig tidspunkt for 2. gangs behandling må vurderes i forhold til værprognosene. 3 ganger behandling kan være aktuelt i høsthvete i år med vedvarende smittepress, og der årkeren har et høyt avlingspotensiale. Kartleggingen av sjukdommer i feltene har vist at det er en rekke sjukdommer til stedet i hveteåkrene, og at sjukdomsfloraen varierer noe fra felt til felt. Dette kan være en årsak til utslag som kan være vanskelig å forklare. Kartleggingen av hvilke bladflekksjukdommer som er til stede i forsøksfeltene er viktig for å kunne differensiere anbefalingene om bekjempelse bedre.

Sammendrag

I 2003 startet et femårig prosjekt som omfatter vekstavslutning i potet. Foreløpige resultater fra forsøkene med vekstavslutning i sorten Folva viser at risdreping 14 dager før høsting reduserer mengden infektive risrester og jord ved høsting og dermed antall knollinfeksjoner sammenlignet med høsting på grønt ris med eller uten behandling med Shirlan (fluazinam) 7 dager før høsting. Likevel reduserte behandlingen med Shirlan (fluazinam) mengden infektive sporer i jord ved høsting sammenlignet med ubehandlet grønt ris. Vekstavslutningsbehandlingene hadde ingen innvirkning på mengden svartskurv og sølvskurv på knollene, men det ble klart mer skade i ledd som var lysgrodd trolig fordi knollene i disse var med fysiologisk modne.

Sammendrag

I 2003 startet et femårig prosjekt i Norge som omfatter vekstavslutning i potet. Studier av tørråte, forårsaket av Phytophthora infestans, på riset, jorda og på knollene er en viktig del av dette prosjektet. Foreløpige resultater med sorten Folva viste at risdreping 14 dager før høsting reduserte antall sporer i riset og i jorda, og reduserte nivået av knollinfeksjoner sammenlignet med høsting på grønt ris med eller uten sprøyting med fluazinam (Shirlan) 7 dager før høsting. Sprøytingen med fluazinam reduserte imidlertid antall levende sporer i jorda ved høsting sammenlignet med ubehandlet grønt ris. Data fra forsøkene  i prosjektet vil bli benyttet til å lage retningslinjer for vekstavslutning i potet blant annet ut fra tørråtesitasjonen i åkeren.

Sammendrag

Hvete fra forskjellige feltforsøk ble analysert for DON. Mengde Fusarium spp. ble bestemt morfologisk og  F. avenaceum, F. langsethiae og trichotecenproduserende gener ved kvantitativ PCR. DON ble funnet i 36 av 51 prøver i lave konsentrasjoner. Alle prøvene var infisert med F. avenaceum. En multippel regresjon viste en sterk korrelasjon mellom DON og værparameterene relativ luftfukighet og mm nedbør ved blomstring og nedbør de to siste ukene før høsting. Behandling med azoksystrobin (Amistar) økte både DON-innholdet og forekomsten av F. culmorum. Det var en positiv signifikant korrelasjon mellom F. avenaceum bestemt morfologisk og ved hjelp av PCR. Det var ingen sikker sammenheng mellom F. culmorum og  tri5 gener bestemt ved kvantitativ PCR.

Sammendrag

Artikkelen orienterer om resultater fra det brukerstyrte FoU-prosjektet "Fysiologiske skader og algesoppråte i kinakål".  Algesopp-problemet i kinakål på åkeren og på lager i Lier skyldes to ulike algesopp-slekter.  På åkeren er det Phytium som er hovedproblemet, og da særlig P. tracheiphilum.  Under lagring er Phytophthora porri hovedårsak til algesoppråten.  Ut fra forsøkene med metalaksyl og ulike dekkmaterialer ser infeksjoner av P. tracheiphilum ut til å skje relativt raskt etter planting.  Forsøk i veksthus for å påvise  ulik resistens mot P. tracheiphilum gav variable resultater, og det har vært vanskelig å skille sortenes resistens.  Feltforsøk på areal med naturlig smitte ser ut til å være sikrest metode til å påvise sortforskjeller