Population dynamics of Heterodera schachtii Schm. and yield response of susceptible and resistant sugar beet (Beta vulgaris L.) after cultivation of susceptible and resistant oilseed radish (Raphanus sativus L.)

Heterodera schachtii zählt zu den wichtigsten Schädlingen der Zuckerrübe. Feldversuche mit dem Ziel, die Ertragsreaktion von Zuckerrübensorten auf Befall mit H. schachtii zu quantifizieren oder den Einfluss der Sorte auf die Populationsdynamik der Nematoden zu beschreiben, werden durch das nesterweise Auftreten im Feld erschwert. Ziel der Untersuchung war es, ein Verfahren zu entwickeln, mit dem eine homogenere Verteilung der Nematoden im Feld erreicht werden kann, sowie den Einfluss unterschiedlicher Populationsdichten von H. schachtii auf den Ertrag einer anfälligen und einer resistenten Zuckerrübensorte zu untersuchen. In den Jahren 2002 bis 2005 wurden 13 Feldversuche in vier Anbauregionen in Deutschland durchgeführt. Im Jahr vor dem Anbau der Zuckerrüben wurden eine anfällige und eine resistente Ölrettichsorte oder eine 50/50-Mischung aus beiden in Streifen angebaut, um die Populationsdichte der Nema­toden an jedem der Standorte zu variieren. Signifikante Unterschiede in der Populationsdichte wurden dabei an sechs der 13 Standorte erzielt. Die anfällige Zuckerrübensorte hatte in allen Versuchen höhere Vermehrungsraten als die resistente, generell nahm die Vermehrungsrate mit steigender Ausgangsdichte der Nematoden (Pi) ab. Mit steigendem Pi-Wert ging der bereinigte Zuckerertrag beider Sorten zurück. Diese Beziehung wurde allerdings nicht an allen Standorten bestätigt. Die Qualität der Rüben wurde nicht durch den Pi-Wert beeinflusst. Insgesamt erscheint die vorgestellte Methodik als zu aufwendig und nicht ausreichend verlässlich für umfangreiche Feldversuchsserien. DOI: 10.5073/JfK.2014.09.01, https://doi.org/10.5073/JfK.2014.09.01Heterodera schachtii is an important pest of sugar beet. Field trials to quantify yield responses of sugar beet varieties to H. schachtii or to assess the effect of variety on population dynamics of the nematode are difficult due to its patchy distribution in the field. The aim of the present study was to develop an experimental method to achieve a more homogeneous distribution of the nematode and to relate yield of susceptible and resistant sugar beet to population density of H. schachtii. From 2002 to 2005, thirteen field trials were conducted in four regions of Germany. In the year prior to sugar beet cultivation, a susceptible and a resistant oilseed radish variety or a 50/50 mix of both were grown in strips to vary population densities of the nematode at each trial site. Significant differences in population densities after oilseed radish cultivation were obtained in six of the thirteen trials. The reproductive rates of H. schachtii were higher under the susceptible than under the resistant sugar beet variety in all trials and generally decreased with increasing initial population density (Pi). In both varieties, white sugar yields decreased with increasing Pi. This relation was not confirmed in all trials. Root quality was not related to Pi. It was concluded that the introduced methodology is too costly and not sufficiently reliable for extensive series of field trials. DOI: 10.5073/JfK.2014.09.01, https://doi.org/10.5073/JfK.2014.09.0

Efficacy of different strategies using an ALS-inhibitor herbicide for weed control in sugar beet (Beta vulgaris L.)

In den Jahren 2013 und 2014 wurden in sechs Umwelten in Deutschland Feldversuche durchgeführt, um die Wirksamkeit eines neuen ALS-Inhibitor Herbizids (F/T) zur Unkrautkontrolle im Zuckerrübenanbau zu bewerten. Fünf Herbizidstrategien mit verschiedenen Anwendungen von F/T (50 g Foramsulfuron ha–1 + 30 g Thiencarbazone-methyl ha–1) und eine klassische Herbizidstrategie mit drei Applikationen von Phenmedipham (75 g Wirkstoff ha–1), Desmedipham (59 g Wirkstoff ha–1), Ethofumesat (94 g Wirkstoff ha–1), Lenacil (34 g Wirkstoff ha–1) und Metamitron (700 g Wirkstoff ha–1) wurden miteinander verglichen. Die Wirksamkeit der klassischen Herbizidstrategie lag zwischen 84 und 99% durch nicht voll­ständig kontrollierte Chenopodium album L., Matricaria recutita L., Mercurialis annua L. und Solanum tuberosum L. Die durchschnittliche Wirksamkeit von F/T lag bei 95% in der einmaligen Applikation. Strategien mit zwei Applikationen in Kombination von klassischen Herbiziden und F/T erreichten eine Wirksamkeit über 97%. Dies führt zu einer höheren Flexibilität der Unkrautkontrolle in Zuckerrüben.In 2013 and 2014, field trials were conducted at six environments in Germany to evaluate the efficacy of a new ALS-inhibiting herbicide containing foramsulfuron and thiencarbazone-methyl (F/T) for weed control in sugar beet cultivation. Five herbicide strategies with different application frequencies of F/T (50 g foramsulfuron ha–1 + 30 g thiencarbazone-methyl ha–1) and a classic herbicide strategy with three applications of phenmedipham (75 g ai ha–1), desmedipham (59 g ai ha–1), ethofumesate (94 g ai ha–1), lenacil (34 g ai ha–1) and metamitron (700 g ai ha–1) were compared. The efficacy of the classic herbicide strategy was between 84 and 99% due to surviving Chenopodium album L., Matricaria recutita L., Mercurialis annua L. and Solanum tuberosum L. Average efficacy of F/T was 95% in the single application treatment. Strategies with two applications combining classic herbicides and F/T achieved an efficacy beyond 97%. This points to an increased flexibility of weed control in sugar beet

Übersicht zu Wirksamkeitsversuchen von Conviso® One in Zuckerrüben

Das Herbizid Conviso One mit den beiden Wirkstoffen Foramsulfuron 50 g l-1 und Thiencarbazone-Methyl 30 g l-1 (HRAC-Gruppe B) benötigt im Zuckerrübenanbau komplementär eine resistente Sorte (sortenspezifische Selektivität). Erfahrungen mit diesen Wirkstoffen in Mais zeigen, dass eine hohe Wirksamkeit auch bei Unkräutern in späteren Wachstumsstadien gegeben ist, während die bisher im Zuckerrübenanbau eingesetzten Herbizide die höchste Effizienz im Keimblattstadium der Unkräuter haben. Um Erkenntnisse bezüglich der Wirkdauer im Boden, der Sensitivität von Unkräutern in verschiedenen Wachstumsstadien und des optimalen Einsatztermins zu gewinnen, wurden in den Jahren 2013 und 2014 vom Institut für Zuckerrübenforschung mehrere Feldversuche angelegt. Dabei wurden Unkräuter der Arten Chenopodium album, Brassica napus, Galium aparine, Matricaria chamomilla und Polygonum convolvulus ausgesät, um die Bodenwirksamkeit (Applikation vor Aussaat der Unkräuter) sowie die Wirksamkeit nach Spritzapplikation in unterschiedlichen Stadien der Unkräuter zu testen. Weitere Versuche auf Praxisflächen unter standorttypischer Verunkrautung dienten zur Ermittlung der Wirksamkeit von Conviso One gegenüber einer Standard- Herbizidstrategie sowie gegenüber Tankmischungen und Spritzfolgen unter Zugabe von Conviso One. Die Ergebnisse zeigen eine abnehmende Wirksamkeit mit zunehmenden Entwicklungsstadien der Unkräuter, vor allem bei C. album. Im Vergleich zu praxisüblichen Herbizidstrategien, die eine erste Behandlung im Keimblattstadium der Unkräuter vorsehen, kann bei Conviso One ein wirksamer Einsatz bis BBCH 14 von C. album erfolgen. Verglichen mit einer Standard-Herbizidstrategie kann durch den Einsatz von Conviso One eine höhere Wirksamkeit gegenüber schwer bekämpfbaren Unkrautarten wie Mercurialis annua und Durchwuchs-Kartoffel (Solanum tuberosum) erreicht werden und die Anzahl der notwendigen Spritzapplikationen sinkt. Die Bodenwirksamkeit betrug im Mittel der Versuche und Jahre 15-20 Tage

XBootes: An X-Ray Survey of the NDWFS Bootes Field - Paper I Overview and Initial Results

We obtained a 5 ksec deep Chandra X-ray Observatory ACIS-I map of the 9.3 square degree Bootes field of the NOAO Deep Wide-Field Survey. Here we describe the data acquisition and analysis strategies leading to a catalog of 4642 (3293) point sources with 2 or more (4 or more) counts, corresponding to a limiting flux of roughly 4(8)x10^{-15} erg cm^{-2}s^{-1} in the 0.5-7 keV band. These Chandra XBootes data are unique in that they consitute the widest contiguous X-ray field yet observed to such a faint flux limit. Because of the extraordinarily low background of the ACIS, we expect only 14% (0.7%) of the sources to be spurious. We also detected 43 extended sources in this survey. The distribution of the point sources among the 126 pointings (ACIS-I has a 16 x 16 arcminute field of view) is consistent with Poisson fluctuations about the mean of 36.8 sources per pointing. While a smoothed image of the point source distribution is clumpy, there is no statistically significant evidence of large scale filamentary structure. We do find however, that for theta>1 arcminute, the angular correlation function of these sources is consistent with previous measurements, following a power law in angle with slope -0.7. In a 1.4 deg^{2} sample of the survey, approximately 87% of the sources with 4 or more counts have an optical counterpart to R ~26 mag. As part of a larger program of optical spectroscopy of the NDWFS Bootes area, spectra have been obtained for \~900 of the X-ray sources, most of which are QSOs or AGN.Comment: 18 Pages, 10 figures (AASTex Preprint format

The Chandra XBootes Survey - III: Optical and Near-IR Counterparts

The XBootes Survey is a 5-ks Chandra survey of the Bootes Field of the NOAO Deep Wide-Field Survey (NDWFS). This survey is unique in that it is the largest (9.3 deg^2), contiguous region imaged in X-ray with complementary deep optical and near-IR observations. We present a catalog of the optical counterparts to the 3,213 X-ray point sources detected in the XBootes survey. Using a Bayesian identification scheme, we successfully identified optical counterparts for 98% of the X-ray point sources. The optical colors suggest that the optically detected galaxies are a combination of z<1 massive early-type galaxies and bluer star-forming galaxies whose optical AGN emission is faint or obscured, whereas the majority of the optically detected point sources are likely quasars over a large redshift range. Our large area, X-ray bright, optically deep survey enables us to select a large sub-sample of sources (773) with high X-ray to optical flux ratios (f_x/f_o>10). These objects are likely high redshift and/or dust obscured AGN. These sources have generally harder X-ray spectra than sources with 0.1<f_x/f_o<10. Of the 73 X-ray sources with no optical counterpart in the NDWFS catalog, 47 are truly optically blank down to R~25.5 (the average 50% completeness limit of the NDWFS R-band catalogs). These sources are also likely to be high redshift and/or dust obscured AGN.Comment: 19 pages, 13 figures, ApJ accepted. Catalog can be found at: http://www.noao.edu/noao/noaodeep or ftp://archive.noao.edu/pub/catalogs/xbootes

Tracing the Nuclear Accretion History of the Red Galaxy Population

We investigate the evolution of the hard X-ray luminosity of the red galaxy population using a large sample of 3316 red galaxies selected over a wide range in redshift (0.3<z<0.9) from a 1.4 deg^2 region in the Bootes field of the NOAO Deep Wide-Field Survey (NDWFS). The red galaxies are early-type, bulge-dominated galaxies and are selected to have the same evolution corrected, absolute R-band magnitude distribution as a function of redshift to ensure we are tracing the evolution in the X-ray properties of a comparable optical population. Using a stacking analysis of 5-ks Chandra/ACIS observations within this field to study the X-ray emission from these red galaxies in three redshift bins, we find that the mean X-ray luminosity increases as a function of redshift. The large mean X-ray luminosity and the hardness of the mean X-ray spectrum suggests that the X-ray emission is largely dominated by AGN rather than stellar sources. The hardness ratio can be reproduced by either an absorbed (N_H ~2 x 10^22 cm^-2) Gamma=1.7 power-law source, consistent with that of a population of moderately obscured Seyfert-like AGN, or an unabsorbed Gamma=0.7 source suggesting a radiatively inefficient accretion flow (e.g., an advection-dominated accretion flow). We also find that the emission from this sample of red galaxies constitutes at least 5% of the hard X-ray background. These results suggest a global decline in the mean AGN activity of normal early-type galaxies from z~1 to the present, which indicates that we are witnessing the tailing off of the accretion activity onto SMBHs in early-type galaxies since the quasar epoch.Comment: 23 pages, accepted for publication in Ap

The Star Formation and Nuclear Accretion Histories of Normal Galaxies in the AGES Survey

We combine IR, optical and X-ray data from the overlapping, 9.3 square degree NOAO Deep Wide-Field Survey (NDWFS), AGN and Galaxy Evolution Survey (AGES), and XBootes Survey to measure the X-ray evolution of 6146 normal galaxies as a function of absolute optical luminosity, redshift, and spectral type over the largely unexplored redshift range 0.1 < z < 0.5. Because only the closest or brightest of the galaxies are individually detected in X-rays, we use a stacking analysis to determine the mean properties of the sample. Our results suggest that X-ray emission from spectroscopically late-type galaxies is dominated by star formation, while that from early-type galaxies is dominated by a combination of hot gas and AGN emission. We find that the mean star formation and supermassive black hole accretion rate densities evolve like (1+z)^3, in agreement with the trends found for samples of bright, individually detectable starburst galaxies and AGN. Our work also corroborates the results of many previous stacking analyses of faint source populations, with improved statistics.Comment: 19 pages, 15 figures, 3 tables, accepted for publication in Ap

Host galaxies, clustering, Eddington ratios, and evolution of radio, X-ray, and infrared-selected AGNs

We explore the connection between different classes of active galactic nuclei (AGNs) and the evolution of their host galaxies, by deriving host galaxy properties, clustering, and Eddington ratios of AGNs selected in the radio, X-ray, and infrared. We study a sample of 585 AGNs at 0.25 < z < 0.8 using redshifts from the AGN and Galaxy Evolution Survey (AGES) and data in the radio (WSRT 1.4 GHz), X-rays (Chandra XBootes), and mid-IR (IRAC Shallow Survey). The radio, X-ray, and IR AGN samples show modest overlap, indicating that to the flux limits of the survey, they represent largely distinct classes of AGNs. We derive host galaxy colors and luminosities, as well as Eddington ratios (lambda), for obscured or optically faint AGNs. We also measure the two-point cross-correlation between AGNs and galaxies on scales of 0.3-10 h^-1 Mpc, and derive typical dark matter halo masses. We find that: (1) radio AGNs are mainly found in luminous red galaxies, are strongly clustered (with M_halo ~ 3x10^13 h^-1 M_sun), and have very low lambda <~ 10^-3; (2) X-ray-selected AGNs are preferentially found in galaxies in the "green valley" of color-magnitude space and are clustered similarly to typical AGES galaxies (M_halo ~ 10^13 h^-1 M_sun), with 10^-3 <~ lambda <~ 1; (3) IR AGNs reside in slightly bluer, less luminous galaxies than X-ray AGNs, are weakly clustered (M_halo <~ 10^12 h^-1 M_sun), and have lambda > 10^-2. We interpret these results in terms of a simple model of AGN and galaxy evolution, whereby a "quasar" phase and the growth of the stellar bulge occurs when a galaxy's dark matter halo reaches a critical mass between ~10^12 and 10^13 M_sun. Subsequently, star formation ceases and AGN accretion shifts from radiatively efficient (optical- and IR- bright) to radiatively inefficient (optically-faint, radio-bright) modes.Comment: 30 emulateapj pages, 21 figures, 3 tables, v2: minor changes match version to appear in Ap

Guided online treatment in routine mental health care: an observational study on uptake, drop-out and effects

<p>Abstract</p> <p>Background</p> <p>Due to limited resources patients in the Netherlands often have to wait for a minimum of six weeks after registration for mental health care to receive their first treatment session. Offering guided online treatment might be an effective solution to reduce waiting time and to increase patient outcomes at relatively low cost. In this study we report on uptake, drop-out and effects of online problem solving treatment that was implemented in a mental health center.</p> <p>Methods</p> <p>We studied all 104 consecutive patients aged 18–65 years with elevated symptoms of depression, anxiety and/or burnout who registered at the center during the first six months after implementation. They were offered a five week guided online treatment. At baseline, five weeks and twelve weeks we measured depressive (BDI-II), anxiety (HADS-A) and burnout symptoms (MBI).</p> <p>Results</p> <p>A total of 55 patients (53%) agreed to start with the online treatment. Patients who accepted the online treatment were more often female, younger and lower educated than those who refused. There were no baseline differences in clinical symptoms between the groups. There were large between group effect sizes after five weeks for online treatment for depression (<it>d</it> = 0.94) and anxiety (<it>d</it> = 1.07), but not for burnout (<it>d</it> = −.07). At twelve weeks, when both groups had started regular face-to-face treatments, we no longer found significant differences between the groups, except for anxiety (<it>d</it> = 0.69).</p> <p>Conclusion</p> <p>The results of this study show that the majority of patients prefer online guided online treatment instead of waiting for face-to-face treatment. Furthermore, online PST increases speed of recovery and can therefore be offered as a first step of treatment in mental healthcare.</p