Pelargonic acid for weed control in onions: factors affecting selectivity

In Zwiebeln (Allium cepa) sind nur wenige Herbizide bewilligt. Aufgrund ihrer aufrecht stehenden Blätter und aufrechten Pflanzenarchitektur bleibt an den Zwiebelpflanzen nach der Applikation weniger Herbizid haften als an breitblättrigen Unkräutern. Außerdem haben sie eine dickere Cuticula. Diese Unterschiede machen einen selektiven Einsatz von Pelargonsäure in Zwiebeln möglich. Das Hauptziel dieser Arbeit war, verträgliche Aufwandmengen für unterschiedliche Wachstumsstadien zu bestimmen. In 5 Feldversuchen wurden 3 Pelargonsäure-haltige Produkte (1 SL- und 2 EC-Formulierungen) mit einem Logsprayer appliziert. Zwischen 0 und 56 kg Aktivsubstanz (a.s.) ha-1 wurden appliziert. Die Zwiebelstadien reichten von BBCH 10 bis 16. Die Verträglichkeit wurde visuell bonitiert. Die Produkte waren verträglich mit jeweils 7.2 und 8.3 ka a.s. ha-1 (BBCH 10-11), 6.1 und 8.9 ka a.s. ha-1 (BBCH 11-12), 8.5 und 20.7 ka a.s. ha-1 (BBCH 13) sowie mit 6.3 und 9.0 kg a.s. ha-1 (BBCH 14-16) für die SL- bzw. die EC-Formulierungen. Die Verträglichkeit hing vom Kulturstadium und den Wetterbedingungen ab. Wichtig für einen selektiven Einsatz in Zwiebeln ist eine intakte Wachsschicht, was eine regenfreie, lichtintensive Periode vor der Applikation bedingt. Pelargonsäure könnte eine wirksame Komponente für eine nachhaltige Unkrautbekämpfung in Zwiebeln werden. Aufgrund der reinen Blattwirkung müssen kleine Unkräuter behandelt werden und es sind mehrere Applikationen notwendig.In onions (Allium cepa) few herbicides are registered. Due to their erect leaf and plant structure, onions retain less herbicide after spraying than broadleaved weeds. Further, onion plants have a thicker plant cuticle. These differences allow a selective use of pelargonic acid in onions. The main aim of this study was to determine the selective dose at different crop growth stages. Five field trials were carried out. Three pelargonic acid containing products (1 SL- and 2 EC-formulations) were applied with a logarithmic sprayer. Dose range was 0 to 56 kg active substance (a.s.) ha-1. The growth stage varied between BBCH 10 and 16. Selectivity was rated visually. The products were selective at 7.2 and 8.3 kg a.s. ha-1 (BBCH 10-11), 6.1 and 8.9 kg a.s. ha-1 (BBCH 11-12), 8.5 and 20.7 kg a.s. ha-1 (BBCH 13) and 6.3 and 9.0 kg a.s. ha-1 (BBCH 14-16) for the SL- and EC-products respectively. Selectivity depended on growth stage and weather conditions. Important for selectivity is an intact cuticle, a rain-free, light-intense period before application. Pelargonic acid could become a component for sustainable weed control in onions. Due to its foliar activity, small weeds need to be targeted and several passes are required

New Substituted Isocoumarins and Dihydroisocoumarins and their Cytotoxic Activities

New isocoumarins were prepared in an efficient way from 2-iodobenzoic acid derivatives and hept-1-yne in a Sonogashira reaction, followed by spontaneous cyclization. Catalytic hydrogenation gave the corresponding dihydroisocoumarins. A 4-chloroisocoumarin was prepared on an alternative pathway. Some of the new compounds showed moderate cytotoxic activities against a human leukemia cell line (HL 60)

Efficacy of herbicides against yellow nutsedge (Cyperus esculentus) plants originating from seeds

Erdmandelgras (Cyperus esculentus) ist ein gefürchtetes Unkraut. Es vermehrt und breitet sich hauptsächlich über Knöllchen aus. Es werden aber auch keimfähige Samen gebildet. Die Samen sind klein und verfügen dementsprechend über wenig Speicherstoffe. Erdmandelgrassämlinge sind zart gebaut und ähneln Süßgräsern (Poaceae). Daher vermuteten wir, dass Erdmandelgrassämlingspflanzen sensibler auf Herbizide reagieren als aus Knöllchen gekeimte Pflanzen. Im Gewächshaus wurden Erdmandelgraspflanzen aus Samen angezogen und mit Glyphosat, Bentazon, Bromoxynil, Pelargonsäure und Clethodim behandelt. Die Herbizidwirksamkeit wurde geschätzt und die Anzahl gebildeter Knöllchen bestimmt. Kein Verfahren zeigte eine volle Wirkung. 4 Wochen nach Behandlung konnte eine Wuchsreduktion um 84 % und 34 % in den Verfahren Glyphosat resp. Bentazon im Vergleich zur unbehandelten Kontrolle beobachtet werden. Bei den anderen Verfahren lag die Wuchsreduktion unter 15 %. In den Verfahren Glyphosat und Bentazon wurden deutlich weniger Knöllchen gebildet als in der unbehandelten Kontrolle. Zusammenfassend konnten wir unsere Hypothese nicht bestätigen. Bereits 6 Wochen nach Keimung waren die Sämlinge robust, vergleichsweise tolerant gegenüber den applizierten Herbiziden mit Ausnahme von Glyphosat und Bentazon und bildeten Knöllchen. Das bedeutet, dass bereits nach sehr kurzer Zeit aus Samen entstandene Erdmandelgrasnester die gleichen Probleme verursachen wie aus Knöllchen entstandene.Yellow nutsedge (Cyperus esculentus) is a troublesome weed. It reproduces and spreads mainly via tubers, but also viable seeds are produced. The seeds are very small and have little resources stored. The seedlings are very fragile and look like grasses (poaceae). We hypothesized that C. esculentus plants originating from seeds are more susceptible to herbicides than plants originating from tubers. Cyperus esculentus plants grown from seeds in the greenhouse were treated with glyphosate, bentazone, bromoxynil, pelargonic acid and clethodim. Herbicide efficacy was rated and produced tubers were counted. None of the treatments achieved full control. Four weeks after application a growth reduction of 84% was observed in the glyphosate treatment, whereas bentazone reduced growth by 34% compared to the control. In the other treatments, growth reduction was < 15%. In the glyphosate and bentazone treatment, considerably fewer tubers were produced than in the control. Concluding, we could not confirm our hypothesis. Already 6 weeks after germination seedlings were well developed, tolerant to the sprayed herbicides, except for glyphosate and bentazone, and produced tubers. This implies, that already after a short time Cyperus esculentus stands originating from seeds pose the same problems as the ones originating from tubers

Long-term corrosion behavior of Al-based coatings in flowing Pb–15.7Li, produced by electrochemical ECX process

RAFM-steels such as Eurofer are considered as structural materials for breeding blankets in future fusion power plants (DEMO). Some of these blankets e.g. HCLL, WCLL and DCLL, use flowing Pb–15.7Li as liquid breeding material. In these concepts, the breeding material will be in direct contact to the structural material at operational temperatures of up to 550 °C. However, bare RAFM steels suffer from strong corrosion attack with corrosion rates between 100 and 400 µm under these conditions. To protect bare RAFM steels from corrosion, Al-based coatings are considered as corrosion barriers. Different coating processes were developed in the past, with focus on electrochemical processes within the last decade. The currently most promising one is the so-called ECX process. Based on the electrodeposition of aluminum from an ionic liquid, it produces smooth and uniform Al enriched scales. These ECX coatings have already shown good short- to mid-term corrosion resistance in flowing Pb–15.7Li for up to 4000 h. In the current study, the long-term corrosion behavior of aluminum-based coatings on Eurofer made by ECX process was investigated. Exposure times of up to 10,000 h in flowing Pb–15.7Li were reached under fusion relevant conditions, i.e. 550 °C and a flow velocity of 0.1 m/s. In comparison to bare Eurofer the corrosion attack is drastically reduced while corrosion rates lay below 20 µm/a. Additionally, it was found that the corrosion behavior is also superior to the corrosion behavior of Al-based barriers produced by the ECA process after long-term exposure in Pb–15.7Li

Long-term corrosion behavior of ODS-Eurofer in flowing Pb-15.7Li at 550°C

Low activation ferritic-martensitic steels (RAFM-steels) are foreseen as structural materials in different blanket designs (HCLL, DCLL, WCLL) with Pb-15.7Li as breeding and partly also as cooling medium. In HCLL and WCLL designs the structural material will be in direct contact with the flowing liquid breeder at operating temperatures up to 550 °C. In the past, investigations concerning the corrosion behavior of RAFM-steels like F82H-mod. and Eurofer showed that these alloys are attacked by the flowing breeder. These corrosion tests pointed out, that the corrosion attack depends mainly on flow velocity and tem- perature. All these alloys were ‘single’ phase ferritic-martensitic steels without any additions. However, structural materials with better strength and creep resistance like ODS-Eurofer or ferritic steels are gath- ering interest in blanket development and will be required at least for DCLL application due to higher operation temperatures. Nevertheless, reliable data concerning compatibility with Pb-15.7Li are missing until now. In this paper results from long-term corrosion testing of ODS-Eurofer will be reported for exposure times up to 1.5 years at a flow velocity of 0.1 m/s. The evaluated data for ODS-Eurofer corrosion will be compared with values of ‘single’ phase ’classical‘ Eurofer. The observed corrosion attack and mechanisms will be discussed in detail considering the testing conditions and the microstructure of the RAFM-steels

Validation of yellow nutsedge (Cyperus esculentus) control strategies in maize in an on-farm, large-scale field trial

A large on-farm field trial was carried out between 2013 and 2015 to investigate the effect of repetitive maize cropping on Cyperus esculentus infestation over time. Intensive control strategies, developed and investigated in small-scale trials, were validated. Four C. esculentus treatment strategies were installed. Soil samples were taken each year put in the greenhouse and the number of C. esculentus sprouts was assessed. Initial infestation was patchy. Field areas were flooded several times due to heavy rainfall. Despite the inherent variability and the adverse weather conditions following conclusions can be drawn: Growing maize combined with intensive weed control (2-4 passes), reduced infestation on average by 80%. Principal components for Cyperus esculentus control strategies are hoeing, the active substances S-metolachlor, mesotrione, terbuthylazine, rimsulfuron, bentazone, and a herbicide containing foramsulfuron, thiencarbazone and iodosulfuron. Growing maize combined with high intensity weed control is an effective approach to manage and reduce C. esculentus infestation. Yield depressions due to this highly intensive weed control cannot be rule out. Nevertheless, farmers in the affected region have adopted these approaches