Pflanzenschutz in ökologisch wirtschaftenden Baumschulen der Bundesrepublik Deutschland

Im Rahmen des Bundesprogramms Ökologischer Landbau wurden aktueller Daten und Erfahrungen zum Vorkommen von Pflanzenschutzproblemen und Bekämpfungsmaßnahmen in ökologisch wirtschaftenden Baumschulen zusammengestellt. Die Daten wurden mit Hilfe einer Umfrage in ökologisch wirtschaftenden Baumschulen und bei Beratern erhoben. Die Befragung der Baumschuler erfolgte überwiegend vor Ort. Die Berater bekamen einen eigenen Fragebogen zugeschickt. Im Jahr 2003 wirtschafteten in Deutschland 44 Baumschulen ökologisch. Von diesen waren 37 nach der EG-Öko-Verordnung (Verordnung (EWG) Nr. 2092/91) zertifiziert, was 1,1 % aller Baumschulen in Deutschland entspricht (insgesamt 3398 Baumschulen im Jahr 2004 nach Angaben des Statistischen Bundesamts, Fachserie 3/Reihe 3.1.7). Von diesen 44 Betrieben nahmen 31 an der Erhebung teil. Insgesamt konnten nur 15 Berater gefunden werden, die ökologisch wirtschaftende Baumschulen bei Pflanzenschutzproblemen berieten. Von diesen 15 Beratern beteiligten sich 11 an der Studie im Jahr 2003. Größe und Struktur der Betriebe war sehr heterogen. Mehr als zwei Drittel der 31 Betriebe waren Sortimentsbaumschulen mit einem breiten Gehölzangebot. Die meisten Baumschulen waren Endverkaufsbaumschulen und richteten ihr Angebot nach dem lokalen Markt aus. Die Hälfte der Baumschuler kultivierte im Wesentlichen wie im konventionellen Anbau. Gedüngt wurde vor allem mit organischen Düngern, einschließlich Gründünger. Stallmist und Kompost waren die am häufigsten verwendeten organischen Stickstoffdünger. Regelmäßige Nmin-Untersuchungen ließen nur etwas mehr als die Hälfte aller Betriebsleiter auf ihren Freilandflächen durchführen. Die Pflanzen wurden sowohl selbst vermehrt als auch als Jungpflanzen zugekauft. Da die verfügbare Menge an ökologisch produziertem Saatgut und vegetativem Vermehrungsmaterial nicht ausreichte, gaben über 80 % der Betriebsleiter an, auch Jungware aus konventionellem Anbau zuzukaufen. Fast alle Betriebsleiter führten selbst regelmäßige Kontrollen auf Schaderregerbefall in ihren Kulturen durch. Bei Pflanzenschutzproblemen zogen die Baumschuler vor allem Fachliteratur zu Rate und fragten andere Baumschulkollegen. Die Berater wurden weitaus seltener um Hilfe gebeten. Die Berater erteilten Hilfe vor allem telefonisch, da diese Beratungsform besonders nachgefragt wurde. Das Auftreten wirtschaftlich bedeutender Schadursachen variierte sehr stark mit dem Betrieb. Die meisten der von den Baumschulern als wirtschaftlich bedeutend eingestuften Schaderreger bereiteten nur in einzelnen Betrieben Probleme. Folgende Schaderreger waren in den Gehölzkulturen besonders schwer bekämpfbar: Blattläuse, Spinnmilben, Echte Mehltaupilze und Rostpilze. Bei den Unkräutern wurden vor allem Gemeine Quecke und Ackerkratzdistel genannt. Die gezielte Änderung des Pflanzensortiments war in den ökologisch wirtschaftenden Baumschulen ein wichtiges Instrument, um einen Befall durch Krankheitserreger und Schädlinge zu vermeiden oder zu minimieren. In den stehenden Kulturen begegneten die Baumschuler den Schaderregern und unerwünschtem Unkrautbewuchs durch verschiedene vorbeugende und direkte Maßnahmen. Eine Beurteilung des Erfolgs der direkten Maßnahmen gaben die Baumschuler jedoch in vielen Fällen nicht ab. Die Berater nannten gezielt für einige Wirt-Erreger-Kombinationen und für einige Unkräuter erfolgreiche Bekämpfungsmaßnahmen. Pflanzenschutzprobleme waren ein wesentlicher begrenzender Faktor für die Sortimentsvielfalt in den ökologisch wirtschaftenden Baumschulen. Fast zwei Drittel der befragten Betriebsleiter mussten wegen Pflanzenschutzproblemen empfindliche Arten und Sorten, insbesondere aus den Sortimentsbereichen Obst und Ziergehölze aus ihrem Sortiment entfernen. Die Berater nannten vor allem Rosen und Obstgehölze, die sich wegen Pflanzenschutzproblemen ökologisch nicht produzieren lassen. Eine Sortimentsvielfalt, wie im konventionellen Anbau ist nach Aussage der meisten ökologisch wirtschaftenden Baumschuler und Berater nicht oder nur mit sehr hohem Aufwand möglich. Die Baumschuler wünschten sich vor allem zu Fragen der Vermarktung und für Pflanzenschutzprobleme Hilfe durch Politik und Forschung. Konkrete Vorschläge für gezielte Untersuchungen werden diskutiert

Entwicklung eines ELISA zum Nachweis von Hepatitis E Antikörpern aus Serum und Fleischsaft des Schweins

Reports on autochthonous Hepatitis E virus (HEV) infection in humans with genotype 3 assume a zoonotic transmission from domestic pigs. But for domestic pigs only limited information on the seroprevalence of HEV in Germany is available. The aim of this study was to develop an ELISA for the detection of anti-HEV IgG and IgM in porcine serum and meat juice, and furthermore asses the seroprevalence in domestic pigs from Bavaria, Germany. 516 serum samples from pigs and 198 corresponding meat-juice samples from 41 different fattening units were collected in four Bavarian slaughterhouses from august 2009 to february 2010. These samples were tested for anti-HEV antibodies using the newly developed recomWell HEV pig (Mikrogen GmbH, Neuried, Germany) with recombinantly produced antigens of genotype 1 and genotype 3 of HEV. The results were compared to a competitor ELISA (Axiom HEV Ab, Axiom GmbH, Bürstadt, Germany). The data were verified by a HEV line-immunoassay (recomLine HEV, Mikrogen), which also uses antigens of genotype 1 and genotype 3 of HEV. Compared to the line-immunoassay the Mikrogen / Axiom ELISA showed a sensitivity of 90.9% / 95.6% and a specificity of 94.0% / 80.8% respectively. The correlation of optical densities (ODs) between serum and meat-juice was 0.939. Taking all three antibody tests into account, we found an overall anti-HEV IgG seroprevalence of 68.60%. 7.0% of the pigs showed IgM antibodies against HEV. We found a significant difference for two slaughterhouses concerning the seroprevalence rates. One fattening unit was free of antibodies against HEV, nine fattening units showed significant influence on the overall seroprevalence rate. This is the first study showing a (very high) anti-HEV reactivity rate in meat-juice of domestic pigs, which corresponds to the seroprevalences measured consistently by three different assays. A positivity rate of 7.0% for IgM has also never been shown before. The used test-systems seem to be suitable for antibody-testing in blood and meat-juice samples from domestic pigs

Stem rot and wilt on Euonymus

Im August 2008 trat an Euonymus japonica eine Stammfäule mit Welke unbekannter Ursache auf. Aus der Triebbasis wurde ein Pilz der Gattung Calonectria (Anamorphe: Cylindrocladium) isoliert (Isolat JKI 2140). Das Isolat wies morphologisch große Ähnlichkeit mit Ca. colhounii, Ca. fujianensis sowie Ca. pseudocolhounii auf, allerdings waren die Konidien im Durchschnitt größer als für diese drei Arten beschrieben. Die Sequenzanalysen ergaben hohe Übereinstimmungen mit Ca. colhounii, Ca. eucalypti, Ca. fujianensis und Ca. pseudocolhounii. Der taxonomische Status des Pilzisolates aus E. japonica ist noch nicht eindeutig geklärt. Es gehört zum Arten­komplex Ca. colhounii, eine sichere Zuordnung zu oder Abtrennung von einer der bekannten Arten aus diesem Komplex lässt sich aber anhand eines einzigen Isolates nicht treffen. Der Pilz wird vorläufig als Calonectria colhounii compl. bezeichnet.Die Pathogenität des Pilzes wurde an E. japonica und an E. fortunei geprüft. Die ursprünglich an E. japonica beobachteten Symptome ließen sich reproduzieren, der Pilz reisolieren. Die Pathogenität von Isolat JKI 2140 an beiden Euonymus-Arten ist damit nachgewiesen. Seit dem Erstauftreten dieses Pilzes gab es keine weiteren Meldungen über eine Stammgrundfäule mit Welkeerscheinungen an Euonymus in Deutschland. Die Bedeutung dieses Erregers an Euonymus ist deshalb als gering einzustufen. DOI: 10.5073/JfK.2015.10.01, https://doi.org/10.5073/JfK.2015.10.01In August 2008, stem rot and wilt symptoms of unknown origin were observed on Euonymus japonica. From the symptomatic stem base a fungus belonging to the genus Calonectria (anamorph: Cylindrocladium) was isolated (isolate JKI 2140). The isolate was morphologically very similar to Calonectria colhounii as well as to Ca. fujianensis and Ca. pseudocolhounii, except for the larger conidia. Sequence analysis of genes (ITS, BT, TEF-1α, HIS3) showed high similarity to Ca. colhounii, Ca. eucalypti, Ca. fujianensis and Ca. pseudocolhounii. The taxonomic status of the fungal isolate from E. japonica is not yet clear. It belongs to the complex Ca. colhounii but a definitive allocation to or separation from a known Calonectria species is not possible on the basis of a single isolate. The fungus is provisionally named Calonectria colhounii compl.The pathogenicity of the fungus was tested on E. japonica and E. fortunei. The disease symptoms originally observed on field plants of E. japonica were reproduced and the fungus was re-isolated. Thus the pathogenicity of isolate JKI 2140 on both Euonymus species is proved. Since the first occurrence of this infestation there were no further notifications of stem canker and wilt on Euonymus spp. in Germany. Therefore the importance of this pathogen on Euonymus is considered to be low. DOI: 10.5073/JfK.2015.10.01, https://doi.org/10.5073/JfK.2015.10.0

Stopping the Rot

Phytophthora species blight potatoes and tomatoes, devastate soybean, rot cacao, and are the cause of sudden oak death. Understanding this versatile genus will be key to its contro

Transition between growth of dense and porous films: theory of dual-layer SEI

The formation of passivating films is a common aging phenomenon, for example in weathering of rocks, silicon, and metals. In many cases, a dual-layer structure with a dense inner and a porous outer layer emerges. However, the origin of this dual-layer growth is so far not fully understood. In this work, a continuum model is developed, which describes the morphology evolution of the solid-electrolyte interphase (SEI) in lithium-ion batteries. Transport through the SEI and a growth reaction governed by the SEI surface energies are modelled. In agreement with experiments, this theory predicts that SEI grows initially as a dense film and subsequently as a porous layer. This dynamic phase transition is driven by the slowing down of electron transport as the film thickens. Thereby, the model offers a universal explanation for the emergence of dual-layer structures in passivating films

Modelling of Lithium Whisker Dissolution

In the search for next generation batteries, lithium metal anode research experiences a refreshed attention due to its high theoretical energy density. Focus lies on enhancing the durability of lithium metal anode batteries and eliminating safety concerns. The battery capacity fades over cycling due to continuous SEI buildup, consuming lithium and electrolyte, and the formation of inactive lithium, which is electrically disconnected from the anode. As the surface of the anode is highly irregular and tends to form whisker during charging, experiments show that during discharge, the tip of the whisker is not dissolved and a droplet stays behind inside the SEI shell. We developed a generalized phase-field model of the dissolution in order to gain insights in the droplet formation process. Utilizing non-equilibrium thermodynamics, our phase-field model describes the dissolution of a single lithium whisker by taking the surface tension of lithium metal into account, and the interaction between lithium and the SEI. We are able to predict the nucleation of a Reyleigh instability behind the tip, leading to the formation of an electronically isolated lithium metal droplet

Modelling of Lithium Droplet Formation During Lithium Dissolutio

Lithium metal anode batteries have regained a lot of research attention as they are promising candidates for next-generation energy storage systems. However, the poor Coulombic efficiency limits the battery’s cyclability. The main causes for low efficiencies are the irreversible loss of active lithium due to the formation of a solid electrolyte interface (SEI) and the formation of unreactive, dead metallic lithium which is disconnected from the current collector. Experiments show that during the dissolution of lithium whiskers, which grow as irregular structures during plating, the tip cannot be dissolved. We developed a generalized phase-field model of the dissolution process to gain insights into the underlying mechanisms of “dead” lithium formation and capacity fade. Our model describes the dissolution of a single lithium whisker in a liquid electrolyte based on lithium surface tension and the interaction between lithium and the interphase, utilizing the framework of non-equilibrium thermodynamics. We study under which circumstances instabilities occur and dead lithium forms. Our model predicts the nucleation of an instability for low stripping current densities, induced by interactions with the SEI. This leads to an incomplete dissolution and the formation of an electrically disconnected metallic lithium droplet, in agreement with optical microscope observations of lithium dissolution

How multiscale modelling can help understand instabilities in the battery's microscale processes

Lithium based batteries are considered for many potential next-generation batteries, employing lithium metal anodes. The performance and durability of lithium batteries are largely influenced by the operating conditions and often find their underlying cause in the nano- and microscale physical processes at the interfaces of the negative electrode. The solid electrolyte interphase (SEI) forms both on graphite and lithium metal, as the potential of the anode is lower than the reduction potential of the electrolyte. The SEI is known to be both a vital part of the battery and a key factor of contributing to its ageing. Although the capacity-fade due to continued SEI growth and, in the case of lithium metal anodes, trapped dead lithium inside the SEI are experimentally well known, fundamental processes are not fully understood and are still under debate. We develop physically motivated mesoscale models to explain observed instabilities on the negative electrode and investigate its dependence on operating conditions. For the continued SEI growth on graphite, we present a surface growth model combined with a diffusion-based SEI growth mechanism. We observe a universal instability that can explain the emergence of a dual-layer SEI with an inner compact layer and an outer porous layer. For lithium metal anodes, we develop a generalized phase-field model of the dissolution of a single lithium whisker covered by SEI. We find that an instability caused by the attraction between lithium metal and SEI leads to the formation of dead lithium

Understanding instabilities in lithium based batteries: dual- layer SEI and isolated lithium formation

Lithium metal batteries with liquid electrolytes have regained attention as candidates for next-generation high-energy-density batteries. However, the low cycle life is an ob-stacle to commercialization. The performance and durability of lithium metal batteries are largely influenced by the operating conditions and often find their underlying cause in the nano- and microscale physical processes at the interfaces of the negative electrode. The continuous growth of solid electrolyte interphase (SEI) consumes lithium and electrolyte. Additionally, stripping is not completely reversible, and parts of lithium remain isolated from the current collector. This so-called isolated lithium remains attached to the an-ode only via an insulating SEI. We develop thermodynamic consistent mesoscale models to explain observed instabili-ties on the negative electrode and investigate its dependence on operating conditions. For the SEI growth under storage conditions, we present a surface growth model combined with a diffusion-based SEI growth mechanism. We observe a universal instability that can explain the emergence of a dual-layer SEI with a compact inner layer and a porous outer layer. For lithium stripping, we present a generalized phase-field model of the dissolution of a single lithium whisker covered by SEI. We find that the instability caused by the interaction between lithium metal and SEI leads to the for-mation of isolated lithium

Modelling of Lithium Whisker Dissolution

In the search for next generation batteries, lithium metal anode research experiences a refreshed attention due to its high theoretical energy density. Focus lies on enhancing the durability of lithium metal anode batteries and eliminating safety concerns. The battery capacity fades over cycling due to continuous SEI buildup, consuming lithium and electrolyte, and the formation of inactive lithium, which is electrically disconnected from the anode. As the surface of the anode is highly irregular and tends to form whisker during charging, experiments show that during discharge, the tip of the whisker is not dissolved and a droplet stays behind inside the SEI shell. We developed a generalized phase-field model of the dissolution in order to gain insights in the droplet formation process. Utilizing non-equilibrium thermodynamics, our phase-field model describes the dissolution of a single lithium whisker by taking the surface tension of lithium metal into account, and the interaction between lithium and the SEI. We are able to predict the nucleation of a Reyleigh instability behind the tip, leading to the formation of an electronically isolated lithium metal droplet