Effectiveness of flufenacet in controlling resistant black-grass (Alopecurus myosuroides Huds.) – comparison of glasshouse and field trial results

In the last years in practice, soil acting herbicides have become the backbone for the control of heavy infestations of grass weed populations. The known unsteady efficacy of HRAC group K1, K3 and N herbicides is controversially discussed and became linked with the development of herbicide resistance. In general, the testing of soil-acting compounds even under controlled glasshouse conditions as well as the confirmation of possible resistance is difficult and needs specific methods and a careful result interpretation. The reliability of test methods is therefore of extreme importance. The reference testing procedure such as plant density, irrigation and temperature conditions have been shown to influence the activity of the soil applied herbicides and to result in extreme differences in the efficacy levels in general, but also in differences between resistant and susceptible biotypes.In our trials, the seed density could be ranked as the most sensitive factor. Of the tested products, Cadou SC was the most consistent herbicide followed by Boxer and Stomp Aqua. Possible reduced efficacy effects in glasshouse trials could not be verified by field trial results. The evaluation of field trials from Northern Germany did not show a significant decrease in sensitivity of black-grass (Alopecurus myosuroides Huds.) to flufenacet or flufenact plus diflufenican. It could be shown that seasonal variation in soil moisture, amount of rainfall, temperature conditions and application timing all influenced the efficacy level in the field the most. Keywords: Enhanced metabolic resistance, herbicide resistance, pendimethalin, prosulfocarb, soil herbicides, test methodologyWirksamkeit von Flufenacet in der Bekämpfung von resistentem Ackerfuchsschwanz (Alopecurus myosuroides Huds.) – Vergleich von Ergebnissen aus Gewächshaus- und FeldversuchenIn den letzten Jahren ist die Anwendung von Bodenherbiziden zu einem zentralen Baustein für die Bekämpfung von hohen Ungrasdichten in der landwirtschaftlichen Praxis geworden. Die schwankende Wirkungssicherheit der Bodenherbizide der HRAC Gruppen K1, K3 und N unter praktischen Feldbedingungen wird teilweise konträr diskutiert und oft mit einer möglichen Resistenzentwicklung in Zusammenhang gebracht. Die allgemeine Untersuchung der Wirksamkeit von Bodenherbiziden unter kontrollierten Gewächshausbedingungen ist schwierig und bedarf einer wirkstoffspezifischen Methodenanpassung und einer entsprechenden überlegten Ergebnisauswertung. Die Vertrauenswürdigkeit der Testmethode ist deshalb von besonderer Bedeutung. Die Vielzahl der Methodenparameter, wie unter anderem Pflanzendichte, Bewässerung und Temperaturbedingungen, beeinflussen die Wirksamkeit der Bodenherbizide und können zu hohen Wirkungsunterschieden im Allgemeinen, aber auch zu Unterschieden zwischen verschiedenen Populationen führen.In der Überprüfung der Methodenparameter stellte sich vor allem die Pflanzendichte als einflussreicher Faktor für die Wirkungsstärke der Bodenherbizide heraus. In der Reihenfolge der getesteten Produkte war Cadou SC das wirkungsstärkste und konsistenteste Produkt, gefolgt von Boxer und Stomp Aqua. Wirkungsunterschiede in den Gewächshausuntersuchungen konnten im Allgemeinen mit den Feldergebnissen nicht bestätigt werden. Eine Auswertung von Feldversuchen aus Resistenzgebieten in Norddeutschland zeigte in den letzten Jahren keine signifikante Abnahme der Wirksamkeit von Flufenacet oder Flufenacet plus Diflufenican in der Bekämpfungsleistung von Ackerfuchsschwanz (Alopecurus myosuroides Huds.). Jahreszeitliche Einflussfaktoren wie Bodenfeuchtigkeit, Niederschlagsereignisse, Temperaturbedingungen und das Wachstumsstadium der Ungräser zum Zeitpunkt der Applikation zeigten einen eindeutigen Einfluss auf die Wirksamkeit der Bodenherbizide. Stichwörter: Bodenherbizide, Herbizidresistenz, Metabolische Resistenz, Pendimethalin, Prosulfocarb, Untersuchungsmethode

Herbizidresistenz von Flughaferherkünften aus Rheinland-Pfalz

2011 wurden in Rheinland-Pfalz zwei und 2012 acht Flughafer-Samenproben (Avena fatua) von Flächen mit unzureichender Herbizidwirkung gesammelt. In zwei aufeinander folgenden Biotests wurden sie auf Herbizidresistenz getestet. Durch Behandlung mit Gibberellinsäure konnte die Entwicklung der Pflanzen vereinheitlicht werden. Geprüft wurden verschiedene ACCase-Hemmer (Ralon Super, Topik 100, Axial 50, Traxos, Focus Ultra) und ein ALS-Inhibitor (Husar OD). Bei drei der 10 Herkünfte waren Kreuzresistenzen gegen ACCase-Inhibitoren nachweisbar. Focus Ultra (Cycloxydim) war nicht betroffen. In zwei Herkünften war die gesamte Population betroffen, während sich Resistenzen bei der dritten Herkunft nur bei einzelnen Pflanzen zeigten. Die genetische Untersuchung ergab bei zwei Herkünften (2011) eine I1781L Target-Site-Mutation. Eine Population (2012) zeigte darüber hinaus die weiteren Target-Site-Mutationen W1999C, I2041V und C2088N. Die Minderwirkungen des ALS-Inhibitors bedürfen weiterer Untersuchungen mit abgestufter Aufwandmenge.Stichwörter: ACCase, ALS, Avena fatua, Biotest, Target-SiteHerbicide resistance of Wild Oat (Avena fatua) populations from Rhineland-PalatinateAbstractIn Rhineland-Palatinate two seed samples of Wild Oat (Avena fatua) were collected in 2011 and eight samples followed in 2012. They derived from fields with inadequate herbicide performance. In order to harmonise plant development, seeds were treated with gibberellic acid. Herbicide resistance was tested by means of two successive biotests using different ACCase-inhibitors (Ralon Super, Topik 100, Axial 50, Traxos, Focus Ultra) and one ALS-inhibitor (Husar OD). Three samples showed cross-resistance against ACCase-inhibitors, with the exception of Focus Ultra (Cycloxydim). Within two populations resistance was well established. Only single plants expressed resistance in a third sample. Genetic analysis found an I1781L target-site-mutation in two samples. One population showed additional mutations: W1999C, I2041V and C2088N. Further investigations, including different application rates, are necessary to explain the poor performance of the ALS-inhibitor.Keywords: ACCase, ALS, Avena fatua, biotest, target sit

Impact of multiple resistance mechanisms in black-grass (Alopecurus myosuroides Huds.) populations on the activity of cereal herbicides

Herbicide resistance to different modes of action is spreading not only in the intensive winter wheat producing areas of Northern Germany, but also in other regions. In this investigation, four selected biotypes of black-grass (Alopecurus myosuroides Huds.) from Lower Saxony, Schleswig-Holstein and Baden-Württemberg were tested for resistance to different herbicides in greenhouse monitoring trials. Using the Pyrosequencing™ technology, leaf material of the different biotypes was screened for ACCase and ALS target-site mutations. The resistance mechanism profiles of the tested biotypes were first completed with metabolism studies of selected herbicides. Finally, the effectiveness of different ACCase and ALS herbicides was investigated in dose response studies under controlled conditions. The results of the analysis showed the occurrence of multiple resistance mechanisms – target-site and non-target site – in the different black-grass biotypes. The calculated resistance factors for the herbicides varied between biotypes and occurring resistance mechanisms. Independent of the range of the resistance factors, low levels already caused decreased effectiveness under real field conditions. Despite confirmed target-site and enhanced metabolic resistances, most of the tested herbicide mixtures and sequence applications provided useful efficacy levels. Soil-acting herbicides have become the backbone for controlling heavy infestations of black-grass populations in practice. Especially flufenacet and its mixtures provide high efficacy levels for the reduction of the first grass weed flush. Within the herbicide strategy study, Atlantis WG® appeared as the most effective post emergence applied product, especially on biotypes with metabolic resistances. With regard to missing alternative solutions in the near future, a mid to long-term sustainable crop-production can only be assured with mixtures and sequence applications of different herbicides and modes of action combined with integrated weed management tools

Empagliflozin in Patients with Chronic Kidney Disease

Background The effects of empagliflozin in patients with chronic kidney disease who are at risk for disease progression are not well understood. The EMPA-KIDNEY trial was designed to assess the effects of treatment with empagliflozin in a broad range of such patients. Methods We enrolled patients with chronic kidney disease who had an estimated glomerular filtration rate (eGFR) of at least 20 but less than 45 ml per minute per 1.73 m(2) of body-surface area, or who had an eGFR of at least 45 but less than 90 ml per minute per 1.73 m(2) with a urinary albumin-to-creatinine ratio (with albumin measured in milligrams and creatinine measured in grams) of at least 200. Patients were randomly assigned to receive empagliflozin (10 mg once daily) or matching placebo. The primary outcome was a composite of progression of kidney disease (defined as end-stage kidney disease, a sustained decrease in eGFR to < 10 ml per minute per 1.73 m(2), a sustained decrease in eGFR of & GE;40% from baseline, or death from renal causes) or death from cardiovascular causes. Results A total of 6609 patients underwent randomization. During a median of 2.0 years of follow-up, progression of kidney disease or death from cardiovascular causes occurred in 432 of 3304 patients (13.1%) in the empagliflozin group and in 558 of 3305 patients (16.9%) in the placebo group (hazard ratio, 0.72; 95% confidence interval [CI], 0.64 to 0.82; P < 0.001). Results were consistent among patients with or without diabetes and across subgroups defined according to eGFR ranges. The rate of hospitalization from any cause was lower in the empagliflozin group than in the placebo group (hazard ratio, 0.86; 95% CI, 0.78 to 0.95; P=0.003), but there were no significant between-group differences with respect to the composite outcome of hospitalization for heart failure or death from cardiovascular causes (which occurred in 4.0% in the empagliflozin group and 4.6% in the placebo group) or death from any cause (in 4.5% and 5.1%, respectively). The rates of serious adverse events were similar in the two groups. Conclusions Among a wide range of patients with chronic kidney disease who were at risk for disease progression, empagliflozin therapy led to a lower risk of progression of kidney disease or death from cardiovascular causes than placebo