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Auftreten der partiellen Taubährigkeit in Weizenbeständen – räumliche Verteilung der Fusarium-Arten und assoziierter Mykotoxine
(2010-01-07)
In den Jahren 2006 und 2007 wurde die räumliche Verteilung von Fusarium spp. und assoziierter Mykotoxine in natürlich infizierten Weizenfeldern auf der Regionalebene und auf der Bestandesebene untersucht. Auf der Regionalebene lagen die beprobten Flächen 100 m bis 10 km auseinander, während auf der Bestandesebene in einem 20 m x 20 m-Raster beprobt wurde. Ein Großteil der Untersuchungen wurde auf rekultivierten Flächen durchgeführt, da deren Bodenhomogenität die Analyse räumlicher Verteilung erleichtert. Die Bestimmung des Befalls mit Fusarium spp. geschah mikrobiologisch und mittels quantitativer PCR. Die Mykotoxinkontamination wurde mit einer Analysemethode (LC-ESI/MS) zum simultanen Nachweis von 32 Mykotoxinen durchgeführt. <br /> Vorherrschende Arten auf den Flächen auf der Regionalebene waren in beiden Jahren F. avenaceum und F. poae. Auch F. culmorum und F. graminearum wurden regelmäßig isoliert. Im Jahr 2006 traten zusätzlich F. proliferatum und F. tricinctum auf. Die Häufigkeit befallener Körner lag mit 7,2 % und 5,9 % in beiden Jahren auf einem ähnlichen Niveau. Unterschiedliche Witterungsbedingungen zwischen Blüte und Ernte führten jedoch zu deutlich unterschiedlichen Befallsintensitäten in beiden Jahren (68 pg mg-1 in 2006, 513 pg mg-1 in 2007). Die Mykotoxine Deoxynivalenol, Zearalenon und Enniatin B wurden in allen Proben nachgewiesen, was deren hohe Bedeutung für die Getreideproduktion unterstrich. 3-Acetyldeoxynivalenol, Moniliformin, Monoacetoxyscirpenol und Nivalenol traten vereinzelt auf, dann aber in relativ hohen Konzentrationen<br /> Die Häufigkeit Fusarium-befallener Körner zeigte in vielen Fällen eine Aggregation im Bestand, was auf die heterogene Verteilung von Ernteresten der Vorfrüchte zurückzuführen war. Bei der Befallsintensität herrschten zufällige räumliche Verteilungen vor. In einigen Fällen wurde eine Tendenz zur Aggregation oder regelmäßigen Verteilung nachgewiesen. Die räumliche Verteilung der Mykotoxinbelastung war abhängig vom Mykotoxin. So traten Deoxynivalenol und Moniliformin vorwiegend zufällig verteilt auf, Enniatin B regelmäßig verteilt und Nivalenol, Zearalenon sowie Zearalenol zeigten ein aggregiertes Auftreten. Der Nachweis verschiedener Verteilungen für die Befallsparameter unterstrich die Bedeutung angepasster und optimierter Beprobungs- und Monitoringstrategien, um die Situation im Bestand adäquat abbilden zu können. <br /> Isolate von F. graminearum aus einem Weizenbestand wiesen eine ähnlich hohe genetische Diversität auf wie Populationen auf höheren Skalenebenen....
<strong>Occurrence of Fusarium head blight in wheat fields - spatial distribution of Fusarium species and associated mycotoxins</strong><br /> Investigations into the spatial distribution of Fusarium spp. and associated mycotoxins in naturally infected wheat fields were carried out in 2006 and 2007, both on a regional and a local scale. On the regional scale the distances between the sampled fields were 100 m to 10 km, whereas the sampling on the local scale was carried out in a 20 m x 20 m-grid. A major part of the investigations took place on recultivated lots where the putative homogeneity of the soil substrate was thought to facilitate the analysis of spatial distributions. Infection with Fusarium spp. was analysed both microbiologically and using quantitative PCR. Mycotoxin contamination was determined using a liquid chromatography method (LC-ESI/MS) for simultaneous detection of 32 mycotoxins.<br /> Predominant species in both years were F. avenaceum and F. poae, whereas F. culmorum and F. graminearum occurred less frequently. In 2006 F. proliferatum und F. tricinctum were also isolated from wheat kernels. The frequency of infected kernels was similar in both years, at 7.2 % in 2006 and 5.9 % in 2007. However, different climatic conditions in the period from flowering to harvest resulted in major differences in fungal biomass between years (68 pg mg-1 in 2006 and 513 pg mg-1 in 2007). The mycotoxins deoxynivalenol, zearalenone and enniatin B were detected in each sample, demonstrating their high relevance in the production of small grain cereals. 3-acetyldeoxynivalenol, moniliformin, monoacetoxyscirpenol and nivalenol were isolated less frequently, but in relatively high concentrations.<br /> The frequency of infected kernels showed aggregated patterns in half of the fields, which was explained by aggregations of residues of the previous crop. The spatial distribution of fungal biomass most frequently had random patterns, although in some cases a tendency to regular and aggregated patterns was observed. The spatial distribution of mycotoxin contamination depended on the mycotoxin. Deoxinivalenol and moniliformin showed predominantly random patterns, whereas enniatin B was largely distributed regularly. Nivalenol, zearalenone and zearalenole showed aggregated patterns. The occurrence of different patterns for the various disease parameters demonstrated the high relevance of adjusted and optimised sampling and monitoring strategies for analysing the disease situation in the field.<br /> Isolates of F. graminearum from one wheat canopy showed a similar high level of genetic diversity to populations on larger scales....
<strong>Occurrence of Fusarium head blight in wheat fields - spatial distribution of Fusarium species and associated mycotoxins</strong><br /> Investigations into the spatial distribution of Fusarium spp. and associated mycotoxins in naturally infected wheat fields were carried out in 2006 and 2007, both on a regional and a local scale. On the regional scale the distances between the sampled fields were 100 m to 10 km, whereas the sampling on the local scale was carried out in a 20 m x 20 m-grid. A major part of the investigations took place on recultivated lots where the putative homogeneity of the soil substrate was thought to facilitate the analysis of spatial distributions. Infection with Fusarium spp. was analysed both microbiologically and using quantitative PCR. Mycotoxin contamination was determined using a liquid chromatography method (LC-ESI/MS) for simultaneous detection of 32 mycotoxins.<br /> Predominant species in both years were F. avenaceum and F. poae, whereas F. culmorum and F. graminearum occurred less frequently. In 2006 F. proliferatum und F. tricinctum were also isolated from wheat kernels. The frequency of infected kernels was similar in both years, at 7.2 % in 2006 and 5.9 % in 2007. However, different climatic conditions in the period from flowering to harvest resulted in major differences in fungal biomass between years (68 pg mg-1 in 2006 and 513 pg mg-1 in 2007). The mycotoxins deoxynivalenol, zearalenone and enniatin B were detected in each sample, demonstrating their high relevance in the production of small grain cereals. 3-acetyldeoxynivalenol, moniliformin, monoacetoxyscirpenol and nivalenol were isolated less frequently, but in relatively high concentrations.<br /> The frequency of infected kernels showed aggregated patterns in half of the fields, which was explained by aggregations of residues of the previous crop. The spatial distribution of fungal biomass most frequently had random patterns, although in some cases a tendency to regular and aggregated patterns was observed. The spatial distribution of mycotoxin contamination depended on the mycotoxin. Deoxinivalenol and moniliformin showed predominantly random patterns, whereas enniatin B was largely distributed regularly. Nivalenol, zearalenone and zearalenole showed aggregated patterns. The occurrence of different patterns for the various disease parameters demonstrated the high relevance of adjusted and optimised sampling and monitoring strategies for analysing the disease situation in the field.<br /> Isolates of F. graminearum from one wheat canopy showed a similar high level of genetic diversity to populations on larger scales....
