Effects of plant extracts on downy mildew of vine-Laboratory and field experiments

Extracts made from leaves, bark, flowers or roots of 23 different plant species using water, alcohol or acetone were tested against downy mildew of vine in laboratory, glasshouse and vineyards. Highest effects were found for Hedera helix (leaves in water), Quercus spec.(bark in alcohol), Primula veris (roots in water), Rhamnus frangula (roots in alcohol), Solidago spec (leaves in alcohol), Salix spec. (bark in water). Extracts of Rhamnus and Primula had significant curative effects (30 - 35%). In the laboratory and glasshouse test protective effects were much better (70- 90% reduction of infection) than the results in field experiments (30 - 40%). Single use of these extracts is insufficient for practical use in viticulture. The use in combinations with stone-meals and low doses of copper should be tested in future

Vergleich verschiedener Kupferformulierungen bei gleicher CU-Aufwandmenge gegen Rebenperonospora

Kupferhaltige Präparate sind bisher eine wichtige Basis für die Peronosporabekämpfung im ökologischen Anbau. Bereits sehr geringe Kupferaufwandmengen haben eine sehr gute Wirkung gegen Rebenperonospora (siehe Kast 1996). Nach dem derzeitigen Stand des Anhangs 2 der EU-Verordnung 2092/91 sind kupferhaltige Präparate allerdings nur noch bis zum 31.03.2002 zulässig. In Deutschland lauft die Zulassung aller Kupferpräparate Ende des Jahres 2000 aus. Inwieweit die Zulassungen verlängert werden können, ist zurzeit offen. Das Schwermetall Kupfer reichert sich bei kontinuierlicher Anwendung allmählich im Boden an und belastet insbesondere auch die Ökosysteme der Oberflächengewässer. Auch bei einer Verlängerung der Zulassungen muss es deshalb im Interesse des ökologischen Anbaus sein, mit möglichst geringen Kupferaufwandmengen auszukommen, um die unerwünschten ökologischen Auswirkungen möglichst gering zu halten. Ziel der vorliegenden Untersuchungen war es deshalb, zu prüfen, ob durch optimierte Formulierungen bei gleicher Kupferaufwandmenge ein besserer Effekt erzielt werden kann

Untersuchungen zur Wirksamkeit von Pflanzenextrakten gegen den Erreger des Falschen Mehltaus der Weinrebe (Plasmopara viticola)

Ziel der Untersuchungen war die Suche nach Naturstoffen, die im ökologischen Weinbau die Anwendung von Kupfer gegen Rebenperonospora ersetzen oder ergänzen könnten. Zu diesem Zweck wurden Extrakte von einheimischen Pflanzen (Pflanzenteilen) zunächst einem Laborscreening unterworfen und die erfolgreichsten Extrakte an Topfpflanzen und schließlich in zwei Freilandversuchen (2000 und 2001) angewandt. Die festgestellten Effekte der Pflanzenextrakte sind zwar signifikant, die im Freiland gefundene Wirkung ist aber für eine praktische Anwendung als Bekämpfungsmittel im ökologischen Weinbau zu gering. Sie wären allenfalls in Kombination z. B. mit Kupfer oder Gesteinsmehlen oder beim Anbau teilresistenter Reben nutzbar

First results with a spore trap for collecting infectious sporangia of downy mildew

Research Not

Survival of sporangia from Plasmopara viticola, the downy mildew of grapevine

Research NoteThe potential of aged sporangia from Plasmopara viticola to produce zoospores as a requirement to form new infections was determined. Sporangia were produced on potted grapevines and kept on the vines at 22 °C, 30 % r.h. or 22 °C, 60-80 % r.h., respectively. Under these conditions release of zoospores from sporangia could be observed microscopically until 7 d after outbreak of sporangia if liquid water was available. After suspending sporangia in water a first release of zoospores from fresh sporangia was observed after 30 min, from 3-7 d old sporangia not before 180 min. Sporangia kept under the above mentioned conditions were able to infect leaves for at least 9 d after outbreak

Effects of microflora composition in the phyllosphere on biological regulation of grapevine fungal diseases

Aqueous fermentation extracts of composted microbiologically active substrates reduced significantly the infestation of grapevine leaves with Plasmopara viticola under growth chamber conditions. Enhancement of efficacy was available through the enrichment of the extracts with nutrients - like sucrose and brewer's yeast - or with a natural surfactant (methylized cellulose). Studies on the microbial composition of the phyllosphere showed that the quantity of the total number of colony forming units, of yeasts/filametous fungi, of enterobacteria, of pseudomonads and of aerobic bacilli depends on the specific amendments to the extracts and on the microclimatic conditions. They ace responsible for the differences in efficiency of the various extracts against P. viticola. Appropriate investigations on the phyllosphere in a field experiment resulted in a different composition of the microflora, though the same combinations of extract amendments were used. This is caused by the varying environmental conditions. In spite of the changed microflora, the disease suppressing effects against Urcinula necator were preserved

Zum Einfluß der Stickstoffdüngung auf den Befall der Reben durch Phomopsis viticola SACC.

Effects of nitrogen supply on infection of grapevines by Phomopsis viticola SACC.The influence of nitrogen supply on the infection of grapevine cv. Kerner by Phomopsis viticola was tested in the field. In years favourable for fungus attack, the rate of infection increased when changing from the lowest N dose to the highest one

Tectonics of a K+ channel: The importance of the N-terminus for channel gating

AbstractThe small K+ channel Kcv represents the pore module of complex potassium channels. It was found that its gating can be modified by sensor domains, which are N-terminally coupled to the pore. This implies that the short N-terminus of the channel can transmit conformational changes from upstream sensors to the channel gates. To understand the functional role of the N-terminus in the context of the entire channel protein, we apply combinatorial screening of the mechanical coupling and long-range interactions in the Kcv potassium channel by reduced molecular models. The dynamics and mechanical connections in the channel complex show that the N-terminus is indeed mechanically connected to the pore domain. This includes a long rang coupling to the pore and the inner and outer transmembrane domains. Since the latter domains host the two gates of the channel, the data support the hypothesis that mechanical perturbation of the N-terminus can be transmitted to the channel gates. This effect is solely determined by the topology of the channel; sequence details only have an implicit effect on the coarse-grained dynamics via the fold and not through biochemical details at a smaller scale. This observation has important implications for engineering of synthetic channels on the basis of a K+ channel pore

Nature of the N-Pd interaction in nitrogen-doped carbon nanotube catalysts

In this work, the geometric and electronic structure of N species in N-doped carbon nanotubes (NCNTs) is derived by X-ray photoemission (XPS) and absorption spectroscopy (NEXAFS) of the N 1s core excitation. Substitutional N species in pyridine-like configuration and another form of N with higher thermal stability are found in NCNTs. The structural configuration of the high thermally stable N species, in the literature often referred to as graphitic N, is assessed in this work by a combined theoretical and experimental study as a 3-fold substitutional N species in an NCNT basic structural unit (BSU). Furthermore, the nature of the interaction of those N species with a Pd metal center immobilized onto NCNTs is of σ-type donation from the filled π-orbital of the N atom to the empty d-orbital of the Pd atom and a π back donation from the filled Pd atomic d-orbital to the π* antibonding orbital of the N atom. We have found that the interaction of pyridine N with Pd is characterized by a charge transfer typical of a covalent chemical bond with partial ionic character, consistent with the chemical shift observed in the Pd 3d core level of divalent Pd. Graphitic N sites interact with Pd by a covalent bond without any charge redistribution. In this case, the electronic state of the Pd corresponds to metallic Pd nanoparticles electronically modified by the interaction with the support. The catalytic reactivity of these samples in hydrogenation, CO oxidation, and oxygen reduction reaction (ORR) allowed clarifying some aspects of the metal carbon support interaction in catalysis

Estimating the Predictive Value of Negative SARS-CoV-2 Results: A Prospective Study

© 2020 by The Society for Healthcare Epidemiology of America. All rights reserved. We performed a prospective study of 501 patients, regardless of symptoms, admitted to the hospital, to estimate the predictive value of a negative Nasopharyngeal swab for SARS-CoV-2. At a positivity rate of 10.2%, the estimated Negative Predictive Value (NPV) was 97.2% and NPV rose as prevalence decreased during the study