Elisabeth Oldenburg

Influence of nitrogen fertilization on deoxynivalenol contamination of winter wheat - experimental field trials and evaluation of analytical methods.

Experimental field trials were carried out to study the influence of N-fertilization on deoxynivalenol (DON) contamination of winter wheat.Within four years of investigation, no definite effect of mineral N-input at dosages varying between 0 and 240 kg N/ha could be observed on DON concentration in wheat grain. The main factors affecting DON contamination of wheat were theFusarium infection pressure, the weather conditions and the susceptibility of the wheat varieties againstFusarium head blight.DON was analyzed with enzyme-linked immunosorbent assay (ELISA) and, for comparison, some of the positive samples were additionally analyzed with high performance liquid chromatography (HPLC). There was a good correlation between the ELISA and the HPLC results for DON concentration in wheat.

Strategies to reduce DON contamination of wheat with different soil tillage and variety systems

With the focus on minimizingFusarium head blight and the deoxynivalenol (DON) contamination of wheat a three year crop rotation system starting with forage maize and followed by two years of winter wheat was combined with three soil tillage systems and selected plant varieties with varying susceptibility toFusarium infection.Higher DON concentrations were generally observed in wheat grain when the soil was mulched rather than ploughed, depending on the mass of maize residues remaining on the soil surface. Maize residues are the most important source ofFusarium inoculum. Infected maize residues had a main impact on the level of DON contamination in wheat grain particularly in the first year after maize cultivation. When the maize stubble was chopped before mulching, the decomposition of the residues was speeded up and the DON contamination of the wheat grain was lower. In the second year following the maize crop, the decomposition of the maize residues/Fusarium biomass was nearly complete and the infection risk was reduced considerably. An influence of the susceptibility of the maize variety against stem rot on the DON concentration of the succeeding winter wheat crop was not observed. The less susceptible wheat variety was suitable for controlling the higher infection risk deriving from the introduction of maize in wheat rotation and the use of mulching techniques.

Fusarium mycotoxins in forage maize - Detection and evaluation

The deoxynivalenol concentrations found in forage maize ranged between 0.24 and 14.29 mg/kg DM (detected by ELISA). When highly contaminated samples were analysed for deoxynivalenol by HPLC or LC-MS the resulting concentrations were in the mean about 50% lower. Furthermore, using LC-MS other type-A and type-B trichothecenes, zearalenone and α-zearalenol were found in these samples. The differences between ELISA and HPLC/LC-MS data for deoxynivalenol are assumed to result from cross-reactions of other trichothecenes with the antibodies used in ELISA and toxin losses from sample purification procedures needed for HPLC and LC-MS analysis.

Fusarium diseases of maize associated with mycotoxin contamination of agricultural products intended to be used for food and feed

Infections of maize with phytopathogenic and toxinogenic Fusarium spp. may occur throughout the cultivation period. This can cause different types of diseases in vegetative and generative organs of the plant. Along with these infections, mycotoxins are often produced and accumulated in affected tissues, which could pose a significant risk on human and animal health when entering the food and feed chain. Most important fungal species infecting European maize belong to the Fusarium sections Discolour and Liseola, the first being more prevalent in cooler and humid climate regions than the second predominating in warmer and dryer areas. Coexistence of several Fusarium spp. pathogens in growing maize under field conditions is the usual case and may lead to multi-contamination with mycotoxins like trichothecenes, zearalenone and fumonisins. The pathways how the fungi gain access to the target organs of the plant are extensively described in relation to specific symptoms of typical rot diseases regarding ears, kernels, rudimentary ears, roots, stem, leaves, seed and seedlings. Both Gibberella and Fusarium ear rots are of major importance in affecting the toxinogenic quality of grain or ear-based products as well as forage maize used for human or animal nutrition. Although rudimentary ears may contain high amounts of Fusarium toxins, the contribution to the contamination of forage maize is minor due to their small proportion on the whole plant dry matter yield. The impact of foliar diseases on forage maize contamination is regarded to be low, as Fusarium infections are restricted to some parts on the leaf sheaths and husks. Mycotoxins produced in rotted basal part of the stem may contribute to forage maize contamination, but usually remain in the stubbles after harvest. As the probability of a more severe disease progression is increasing with a prolonged cultivation period, maize should be harvested at the appropriate maturity stage to keep Fusarium toxin contamination as low as possible. Ongoing surveillance and research is needed to recognise changes in the spectrum of dominating Fusarium pathogens involved in mycotoxin contamination of maize to ensure safety in the food and feed chain.

Infection process and mycotoxin production in Fusarium culmorum-infected maize ears

Infection process and mycotoxin production in Fusarium culmorum-infected maize ears Red ear rot of maize is an important disease in Europe caused by toxigenic Fusarium species like F. graminearum and F. culmorum. To get detailed information about the pathogenesis of the disease and the Fusarium toxin production in infected ears a field study was conducted with maize which was artificially inoculated with F. culmorum at the stage of female flowering. Every fortnight after inoculation, maize ears of two varieties were harvested and analysed for the progress of visual signs of the disease and related Fusarium toxin contamination. During the last harvest in mid October, external infection symptoms showing some small pale or brown-marbled kernels with dark brown rachillae were only observed at the ear tip, whereas internal symptoms visible within the rachis were much more pronounced and showed greyish -brownish or pink discolouration of the pith. The symptoms observed in rachis and kernels corresponded with the toxin contamination showing considerably higher concentrations in the rachis compared to the kernels and a top-down gradient from high to low toxin levels within the ear. This suggests that F. culmorum first infects the rachis from the tip towards the bottom, as it subsequently does the kernels via the rachillae connected to the rachis. As infection symptoms and mycotoxin production were much more pronounced in the rachis than in the kernels, red ear rot evaluation should be improved by observing signs of the disease in both kernels and the rachis.

Distribution of deoxynivalenol inFusarium-infected forage maize

A time course study was carried out to assess the appearance and distribution of DON in different organs of forage maize cultivated in the field. DON was produced after the flowering period and increased until harvest to high amounts in the rudimentary ears and leaf sheaths/leaf blades deriving from nodes located below the ear node, whereas nodes and internodes were either not or only slightly contaminated with DON. Genrally, DON was not detected in the ears, including husks, during the whole cultivation time.Fusarium biomass determined in the infected organs confirmed these findings. It seems that the contribution of DON containing rudimentary ears, leaf sheaths and leaf blades to the total DON contamination of forage maize is so far widely underestimated. Therefore advanced evaluation procedures are recommended to get a better understanding of the infection and contamination process and to prove genotypic differences in the resistance of forage maize genotypes againstFusarium infection.

Fusarium mycotoxins in forage maize - occurrence, risk assessment, minimization.

AbstractThe deoxynivalenol contents of forage maize in this study ranged between 0.22 and 12.9 mg/kg DM, but seldom exceeded critical concentrations suggested for ruminant diets. Zearalenone was found in considerably lower concentrations than DON and rarely reached critical levels. Therefore risk to the health and performance of ruminants is regarded as low. Fusarium toxin occurrence in forage maize can be minimized by choosing maize varieties less susceptible to stem rot, harvesting at optimal maturity (dry matter content 30–35%) and elevating the cutting height to at least 40 cm above ground.

Einfluss der Turcicum-Blattdürre (Setosphaeria turcica) auf den Kolbenertrag von Mais

Die Daten der Vergleichsbetriebe stellen den Status quo im Pflanzenschutz in Deutschland dar. Der Behandlungsindex in Mohre und Frischkohl betrug im Durchschnitt der Jahre (2007-2014) bei 6,2 bzw. 9,2. Mohren wurden vorrangig mit Herbiziden und Frischkohl mit Insektiziden behandelt. Unter dem Aspekt des Pflanzenschutzes und zur Reduktion der Behandlungsintensitat mit Insektiziden kann Abbildung 1: Behandlungsindex der Herbizide (Herbizid-BI) in Abhangigkeit der Vorfrucht in den Vergleichsbetrieben fur Mohre, 2007-2014, in Deutschland, ungleiche Buchstaben symbolisieren signifikante Unterschiede (p<0,05), nBlattfrucht=58, nGemuse=28, nHalmfruchte=115 208 72. ALVA-Tagung, Seminarhotel Wesenufer, 2017 der Fruhkohlanbau empfohlen werden. Im Kohl- und Mohrenanbau konnen Halmvorfruchte Schadlingsbefall vorbeugen. Die Mittelaufwandmengen wurden vorrangig bei Herbizidanwendungen reduziert In beiden Kulturen wurden Abweichungen vom notwendigen Mas verzeichnet. Die Pflanzenschutzberatung sowie die regelmasige Durchfuhrung von Bonituren konnen Pflanzenschutzmittelanwendungen dem notwendigen Mas naher bringen und die Umsetzung des IPS in der Praxis verbessern. Fur die Ausschopfung nichtchemischer Masnahmen sind Praxisdemonstrationen und der intensive Austausch zwischen Wissenschaft und Praxis notig, genauso wie Forschungsforderung zur Entwicklung neuer und Optimierung bestehender integrierter Verfahren und neuer Wirkstoffe. Vorbildhaft wird der IPS von den Demonstrationsbetrieben u. a. in den Kulturen Mohre und Weiskohl, seit 2014 umgesetzt. Die Betriebe werden individuell und intensiv betraten, um Pflanzenschutzmittelanwendungen auf das notwendige Mas zu beschranken. Hierfur werden Bonituren unter Nutzung von Schadschwellen, Warndiensthinweisen und Monitoringverfahren durchgefuhrt.

Bewertung der Maiskolbenfusariose mittels Spektralbildanalyse

Die Zusammensetzung der Ackerunkrautflora entspricht einer Anpassung an die standortspezifischen Umweltbedingungen, dem Produktionsverfahren hinsichtlich insbesondere der Fruchtfolge und Bodenbearbeitungstechnik, sowie dem jeweiligen Herbizidmanagement. Da die Art und Intensität der Unkrautflora einen erheblichen Einfluss auf die Ertragsfähigkeit und Wirtschaftlichkeit im Ackerbau ausübt, sollte die Produktionstechnik eine nachhaltige Zunahme des Unkrautbesatzes vermeiden. Dies gilt insbesondere für die Art und Intensität der chemischen Unkrautregulierung. In einem Langzeitversuch bei Zurnhausen (11.769° öL., 48.426° nB., WGS84), Landkreis Freising wird seit 2006 der Einfluss einer unterschiedlichen Pflanzenschutzmittelintensität in einer Fruchtfolge mit Winterweizen, Wintergerste und Silomais untersucht. Die vollständige, stationäre Fruchtfolge wird zudem unter dem Regime einer tief-wendenden und nicht-wendenden Bodenbearbeitung durchgeführt. Der Exaktversuch wird auf Großparzellen mit je 60 m2 in vierfacher Wiederholung nach den Vorgaben der einschlägigen EPPO-Richtlinien durchgeführt. Die Herbizidbehandlung erfolgt in den Intensitätsstufen 100 %, 75 % und 50 % Aufwandmenge einer ortsüblichen Herbizidauswahl bzw. -kombination. Die Entwicklung der Unkrautflora wird durch Auszählungen vor dem jeweiligen Herbizideinsatz erfaßt. Der Einfluss der Herbizidbehandlungsintensität auf das Unkrautspektrum und die Unkrautbesatzdichte wird in Abhängigkeit von der Art der Grundbodenbearbeitung detailiert dargestellt und hinsichtlich den Anpassungspotenzial der Herbizidaufwandmenge diskutiert. Hierzu werden auch die erhobenen Ertragsdaten und die Produktionswirtschaftlichkeit herangezogen.

Bodenfauna als Ökologischer Dienstleister – Collembolen und Nematoden fördern den Abbau von Deoxynivalenol in Fusarium-infiziertem Weizenstroh

ZusammenfassungIn einem Laborexperiment mit Minicontainern kamen fungivore Schlüsselvertreter der Bodenfauna zum Einsatz: Folsomia candida (Collembola) und Aphelenchoides saprophilus (Nematoda). Unsere Hypothese war, dass die Bodentiere den Abbau von Fusarium und dessen Mykotoxin Deoxynivalenol (DON) in Weizenstroh fördern. Des Weiteren wurde untersucht, ob eine unterschiedliche Bodentextur (Sand, Schluff, Ton) Auswirkungen auf die Abbauleistung der Tiere hat. Die Minicontainer beinhalteten Stroh (künstlich mit F. culmorum infiziert, nicht infiziert), Boden und Versuchstiere in unterschiedlicher Anzahl und Kombination (Reinkultur, Mix, Kontrollvariante ohne Tiere). Nach 2 und 4 Wochen wurden Boden- und Strohproben entnommen und mittels ELISA-Analytik auf Fusarium-Biomasse und DON-Konzentration untersucht.Nach vier Wochen wurde in allen Varianten eine starke Abnahme der Fusarium-Biomasse gemessen und auch die DON-Konzentration wurde signifikant reduziert. Der größte DON-Abbau erfolgte in den gemischten Varianten (Collembolen und Nematoden). Die DON-Abbauraten im Stroh der Minicontainern mit sandigem und schluffigem Boden waren signifikant höher als in solchen mit Ton. Aus den Ergebnissen lässt sich schließen, dass die eingesetzten Bodentiere den Abbau von DON fördern. Die Interaktion zwischen Collembolen und Nematoden erwies sich als entscheidend für die Reduzierung der DON-Konzentration in Weizenstroh. Demnach leisten die gewählten Versuchstiere einen wichtigen Beitrag zur Förderung der Bodengesundheit insbesondere in Sand- und Schluffböden.AbstractA minicontainer-study under laboratory conditions was conducted with the following fungivorous members of soil fauna: Aphelenchoides saprophilus, Nematoda and Folsomia candida, Collembola. The objective was to investigate, if the introduced soil fauna is able to reduce the concentration of Fusarium-biomass and the mycotoxin deoxynivalenol (DON) in wheat straw. Furthermore, the study aimed wether the degradation efficiency is affected by different soil texture (sandy loam, silt loam, clay loam). Therefore, minicontainer were filled with soil and wheat straw. Soil fauna was introduced in different combination into the minicontainer (single collembolan, single nematode, faunal interaction and a non-faunal treatment). The minicontainer were divided into 2 sets: one set received artificially Fusarium-infected and DON-contaminated wheat straw, the second set received non-infected straw. After 2 and 4 weeks, soil and straw were sampled for analysing Fusarium-biomass and DON content by using ELISA-technique. After 4 weeks Fusarium-biomass was reduced notably and DON-concentration was degraded significantly throughout all treatments. The highest reduction of DON-concentration was found in the faunal interaction treatment. The DON-concentration in the sandy- and silt loam treatments were reduced more efficiently compared to the clay loam treatment. We conclude that nematodes and collembolans contribute to the degradation of Fusarium-biomass and the mycotoxin DON in wheat straw as ecosystem services.