psbA mutation (Ala251 to Val) in Chenopodium album resistant to triazinones

C

Differential sensitivity of locally naturalized Panicum species to HPPD- and ALS-inhibiting herbicides

Panicum schinzii (Transvaal millet), P. dichotomiflorum (Fall panicum) and P. capillare (Witchgrass) are alien panicoid grasses that have gradually spread and are now locally naturalized in corn fields in Belgium. One of the possible reasons for their expansion in corn fields might be a lower sensitivity to post-emergence herbicides acting against panicoid grasses, in particular those inhibiting 4-hydroxyphenyl pyruvate dioxygenase (HPPD) and acetolactate synthase (ALS). Dose-response pot experiments were conducted in the greenhouse to evaluate the effectiveness of five HP-PD-inhibiting herbicides (sulcotrione, mesotrione, isoxaflutole, topramezone, tembotrione) and two AILS-inhibiting herbicides (nicosulfuron, foramsulfuron) for controlling populations of P. schinzii, P. dichotomiflorum and P. capillare (all naturalized Belgian populations except for P. capillare). In another dose-response pot experiment, sensitivity of five local P. dichotomiflorum populations to HPPD-inhibitors and nicosulfuron was investigated. Finally, the influence of growth stage at time of herbicide application on efficacy of topramezone and nicosulfuron for Panicum control was evaluated. Large interspecific differences in sensitivity to HPPD-inhibiting herbicides were observed. Panicum schinzii was sensitive to tembotrione but moderately sensitive to topramezone and poorly sensitive to mesotrione and sulcotrione. However, P. dichotomiflorum was sensitive to mesotrione and topramezone but moderately sensitive to tembotrione. All Panicum species were sensitive to low doses of nicosulfuron and foramsulfuron. Naturalized P. dichotomiflorum populations exhibited differential herbicide sensitivity profiles. All species tested showed a progressive decrease in sensitivity to topramezone and nicosulfuron with seedling age. A satisfactory post-emergence control of Panicum species in the field will require appropriate choice of herbicide and dose, as well as a more timely application (i.e. before weeds reach the four leaves stage)

Impact of the quality of organic amendments on size and composition of the weed seed bank

In addition to improving the soil quality, organic amendments of soils may affect weed seed survival, emergence, growth and reproduction. This study evaluated the effects of applications of different qualities of organic amendments on size and composition of the weed seed bank in a field under sequential cropping over 4 years. Fertilisation systems tested included farmyard manure, vegetable fruit and garden waste compost, two types of farm compost differing in carbon:nitrogen (C:N) ratio, cattle slurry and mineral fertiliser. All organically amended plots received equal amounts of C. Crop growth was equalised on all plots by applying supplemental mineral N. Seed bank sampling took place in May 2009 to a depth of 10 cm. The weed seed bank was analysed using the seedling emergence method. Despite equal crop growth in fertilised plots, total seed bank density was lowest in plots amended with compost with low C:N ratio and highest in slurry-amended plots. Observed differences in seed bank densities reflected differences in soil organic carbon content and microbial biomass. At plot level, hard-coated seeds in the seed bank (e.g. Chenopodium spp.) were inversely related to soil microbial activity. Observed differential responses of species to applied fertilisers might be attributed to interspecific differences in resistance against microbial seed degradation. Compost-based fertilisation systems could be sustainable tools for incorporation into integrated weed control strategies aiming at depleting the weed seed bank

Differential sensitivity of locally naturalized Panicum species to 4-hydroxyphenyl pyruvate dioxygenase and acetolactate synthase-inhibiting herbicides

One of the possible reasons for the expansion of the alien panicoid grasses Panicum schinzii (Transvaal millet), Panicum dichotomiflorum (Fall panicum) and Panicum capillare (Witchgrass) in maize fields in Belgium might be a lower sensitivity to post-emergence herbicides acting against panicoid grasses, in particular those inhibiting 4-hydroxyphenyl pyruvate dioxygenase (HPPD) and acetolactate synthase (ALS). Dose-response pot experiments were conducted in the greenhouse to evaluate the effectiveness of five HPPD-inhibiting herbicides (sulcotrione, mesotrione, isoxaflutole, topramezone, tembotrione) and two ALS-inhibiting herbicides (nicosulfuron, foramsulfuron) for controlling naturalized Belgian populations of P. schinzii, P. dichotomiflorum and P. capillare. In another dose-response pot experiment, sensitivity of five local P. dichotomiflorum populations to HPPD-inhibitors and nicosulfuron was investigated. Finally, the influence of growth stage at time of herbicide application on efficacy of topramezone and nicosulfuron for Panicum control was evaluated. Large interspecific differences in sensitivity to HPPD-inhibiting herbicides were observed. Panicum schinzii was sensitive (i.e., required a three-fold lower dose than maximum authorized field dose to achieve 90% reduction in biomass) to tembotrione but moderately sensitive (i.e. required maximum field dose) to topramezone and poorly sensitive (i.e. required three-fold higher dose than maximum field dose) to mesotrione and sulcotrione. However, P. dichotomiflorum, a species that morphologically closely resembles P. schinzii, was sensitive to mesotrione and topramezone but moderately sensitive to tembotrione. Panicum capillare was sensitive to sulcotrione and topramezone, moderately sensitive to tembotrione and poorly sensitive to mesotrione. All Panicum species were sensitive to low doses of nicosulfuron and foramsulfuron. Naturalized Panicum dichotomiflorum populations exhibited differential herbicide sensitivity profiles. All species tested showed a progressive decrease in sensitivity to topramezone and nicosulfuron with seedling age. A satisfactory post-emergence control of Panicum species in the field will require appropriate choice of herbicide and dose, as well as a more timely application (i.e. before weeds reach the four leaves stage).Keywords: Bioassay, herbicide sensitivity, leaf stage, nicosulfuron, panicoid grasses, triketoneDifferentielle Sensitivität von lokal naturalisierten Panicum-Arten gegenüber 4-Hydroxyphenylpyruvat-Dioxygenase und Acetolactat- Synthase hemmenden HerbizidenZusammenfassungEiner der möglichen Gründe für die rasche Ausbreitung der standortfremden Unkrauthirsen Panicum schinzii (Glattblättrige Hirse), Panicum dichotomiflorum (Gabelästige Rispenhirse) und Panicum capillare (Haarästige Rispenhirse) in Maisfeldern in Belgien könnte eine geringere Empfindlichkeit gegenüber Nachauflaufherbiziden sein, insbesondere 4-Hydroxyphenylpyruvat-Dioxygenase (HPPD)- und Acetolactat-Synthase (ALS)-Hemmer. Dosis-Wirkungs-Experimente wurden im Gefäßversuch im Gewächshaus durchgeführt, um die Wirksamkeit von fünf HPPD-inhibierenden Herbizidwirkstoffen (Sulcotrione, Mesotrione, Isoxaflutole, Topramezone, Tembotrione) und zwei ALS-inhibierenden Herbizidwirkstoffen (Nicosulfuron, Foramsulfuron) gegen naturalisierte belgische Populationen von P. schinzii, P. dichotomiflorum und P. capillare zu beurteilen. In einem weiteren Dosis-Wirkungs-Topf Experiment wurde die Empfindlichkeit von fünf lokal eingewanderten P. dichotomiflorum-Populationen gegenüber HPPD-Inhibitoren und Nicosulfuron untersucht. Schließlich wurde der Einfluss des Blattstadiums zum Zeitpunkt der Herbizid-Anwendung auf Wirksamkeit von Topramezone und Nicosulfuron für Panicum-Bekämpfung ausgewertet. Große interspezifische Unterschiede in der Empfindlichkeit gegenüber HPPD-inhibierenden Herbiziden wurden beobachtet. Panicum schinzii war empfindlich gegenüber Tembotrione aber mäßig empfindlich gegenüber Topramezone und leicht empfindlich gegenüber Mesotrione und Sulcotrione. Dagegen war P. dichotomiflorum empfindlich gegenüber Mesotrione und Topramezone aber mäßig empfindlich gegenüber Tembotrione. Panicum capillare war empfindlich gegenüber Sulcotrione und Topramezone, mäßig empfindlich gegenüber Tembotrione und leicht empfindlich gegenüber Mesotrione. Alle Panicum-Arten waren empfindlich gegenüber niedrigen Dosen von Nicosulfuron und Foramsulfuron. Eingebürgerte Panicum dichotomiflorum-Populationen zeigten differentielle Herbizid-Empfindlichkeitsprofile. Alle untersuchten Arten zeigten eine fortschreitende Abnahme der Empfindlichkeit gegenüber Topramezone und Nicosulfuron mit zunehmendem Blattstadium. Eine befriedigende Nachauflaufbekämpfung von Panicum-Arten in Maisäckern benötigt eine angemessene Wahl von Herbizid und Dosis sowie eine rechtzeitige Anwendung (das heißt vor dem Vierblattstadium).Stichwörter: Biotest, Blattstadium, Herbizidempfindlichkeit, Nicosulfuron, Triketone, Unkrauthirse

Outcome in patients perceived as receiving excessive care across different ethical climates: a prospective study in 68 intensive care units in Europe and the USA

Purpose: Whether the quality of the ethical climate in the intensive care unit (ICU) improves the identification of patients receiving excessive care and affects patient outcomes is unknown. Methods: In this prospective observational study, perceptions of excessive care (PECs) by clinicians working in 68 ICUs in Europe and the USA were collected daily during a 28-day period. The quality of the ethical climate in the ICUs was assessed via a validated questionnaire. We compared the combined endpoint (death, not at home or poor quality of life at 1 year) of patients with PECs and the time from PECs until written treatment-limitation decisions (TLDs) and death across the four climates defined via cluster analysis. Results: Of the 4747 eligible clinicians, 2992 (63%) evaluated the ethical climate in their ICU. Of the 321 and 623 patients not admitted for monitoring only in ICUs with a good (n = 12, 18%) and poor (n = 24, 35%) climate, 36 (11%) and 74 (12%), respectively were identified with PECs by at least two clinicians. Of the 35 and 71 identified patients with an available combined endpoint, 100% (95% CI 90.0–1.00) and 85.9% (75.4–92.0) (P = 0.02) attained that endpoint. The risk of death (HR 1.88, 95% CI 1.20–2.92) or receiving a written TLD (HR 2.32, CI 1.11–4.85) in patients with PECs by at least two clinicians was higher in ICUs with a good climate than in those with a poor one. The differences between ICUs with an average climate, with (n = 12, 18%) or without (n = 20, 29%) nursing involvement at the end of life, and ICUs with a poor climate were less obvious but still in favour of the former. Conclusion: Enhancing the quality of the ethical climate in the ICU may improve both the identification of patients receiving excessive care and the decision-making process at the end of life