Drycore Appears to Result from an Interaction between Rhizoctonia solani and Wireworm (Agriotes ssp.)—Evidence from a 3-Year Field Survey

Drycore is an important quality deficiency in Europe especially in organic potato production and after grass clover leys. The drycore symptom is attributed to Rhizoctonia solani Kühn (teleomorph: Thanatephorus cucumeris (Frank) Donk). In the framework of a 3-year survey (2001–2003), data concerning potato quality, crop rotation, management, and site parameters were analysed from 185 potato fields. The hypothesis was tested that injuries on potatoes caused by wireworms facilitate the penetration of R. solani and favour the formation of drycore. Analysis of variance showed a significant influence of wireworm damage, seed quality, and grass clover leys in the crop on the level of drycore damage. On fields which had both a low occurrence of black scurf on the seed tubers and a low occurrence of wireworm damage at harvest, significant drycore damage was never observed. The relative risk for drycore damage on tubers was significantly higher if black scurf or wireworm damage was on the same tuber. In contrast, no higher risk for drycore was observed on tubers with slug damage. Abiotic factors like farm manure application, organic matter content, texture, and pH of the soil also had no significant influence on the level of drycore. Thus, the wounding of potatoes by wireworm could be confirmed as the major variable for drycore. The mode of action has to be clarified under controlled conditions

Evaluation of fluopyram for the control of Ditylenchus dipsaci in sugar beet

Fluopyram, a succinate dehydrogenase inhibitor fungicide, has shown potential in controlling Meloidogyne incognita and Rotylenchus reniformis in tomato. The effectiveness of this compound for the control of Ditylenchus dipsaci in sugar beet was evaluated. In this study, laboratory, growth chamber, glasshouse, and field experiments were conducted. In a motility bioassay, the EC50 value was determined with 3.00 μg/ml a.i. after 72 h exposure to fluopyram. The growth chamber experiment did not show any effects on D. dipsaci penetration rate; however, field experiments revealed a positive effect of fluopyram applied at planting in reducing D. dipsaci infectivity. The glasshouse experiment confirmed a limited effect of fluopyram on D. dipsaci population development. Under field conditions, despite a reduction of D. dipsaci penetration rates in spring, fluopyram was not effective in reducing the population development until harvest. Consequently, D. dipsaci densities in plant tissue and soil were high at harvest and not different among treatments. However, root-rot symptoms were significantly reduced at harvest. Fluopyram applied at planting showed good potential to reduce root-rot symptoms caused by D. dipsaci in sugar beet. However, for the long-term reduction of nematode populations in soil, further integrated control measures are needed to reduce the risks of substantial yield losses by D. dipsaci

Bestimmung der Kocheigenschaften von Kartoffeln im Handel

Mit Hilfe eines Farbleitsystems werden Speisekartoffeln zunehmend nach ihren Kocheigenschaften (Kochtyp) deklariert und verkauft. Der Handel stützt sich dabei auf einen sortentypischen Kochtyp. Warenpartien, welche aufgrund von Umwelteinflüssen davon abweichen, führen zu Kundenunzufriedenheit. In einem dreijährigen Projekt, untersuchten wir den Einfluss der Sorte, der Knollendichte (d.h. Stärkegehalt) und der Herkunft auf die Kochqualität von Kartoffeln und entwickelten Möglichkeiten zur Einschätzung einzelner Warenpartien. Das Projekt wurde durch die Förderorganisation für Innovation des Bundes (KTI) und swisspatat unterstützt. Knollen von fünf Sorten und 65 Parzellen wurden aufgrund ihrer Dichte in 192 Fraktionen eingeteilt und sensorisch sowie gerätetechnisch geprüft. Die Kocheigenschaften variierten mit der Dichte sowohl zwischen als auch innerhalb von Parzellen deutlich. Sie wurden im Wesentlichen durch die beiden Faktoren Sorte und Knollendichte bestimmt. Die Ergebnisse deuten zudem darauf hin, dass mit einer Kombination der Dichtebestimmung und einer visuellen Bonitur des Zerkochens wichtige Kocheigenschaften auch ohne Vorkenntnisse zur Sorte eingeschätzt werden können. Die Erkenntnisse tragen dazu bei, die Verwertung der Kartoffelpartien weiter zu optimieren

Optimisation de la fumure soufrée par estimation du risque de carence

Les résultats d'essais de fertilisation soufrée conduits pendant quatre saisons de cultures ont permis d'améliorer un système de prévision du risque de carence en soufre présenté en 2001 dans les Données de Base pour la Fumure des grandes Cultures et des Herbages (RYSER et al., 2001). Ce modèle à points, basé sur des critères agronomiques et pedo-climatiques, a permis d'expliquer 85% de la variabilité du rendement du colza d'automne en réponse à la fumure soufrée. Dans l'ordre d'importance, les facteurs explicatifs étaient la profondeur du sol, le pourcentage d'argile, la matière organique et l'azote disponible. De plus, les précipitations d'octobre à mars, la pierrosite du soi et la fréquence d'application d'engrais organique ont également été prises en compte dans l'attri-bution des points. Le risque de carence a été divisé en trois catégories. Le seuil du risque de carence faible a été fixé à 24 points et aucune fertilisation soufrée n'est préconisée pour ce niveau de risque. La fumure optimale pour un risque modéré de 15 à 23 points a été établie à 35 kg S/ha. Le risque élevé de carence (inférieur à 15 points) n'était pas présent dans les essais mais une recommandation de 60 kg S/ha a été fixée pour ce niveau. La fumure soufrée a entraîné un accroissement significatif du prélèvement de S par la plante. Après l'application de fumure soufrée, la teneur en glucosinolates des grains de colza était significativement plus élevée dans tous les cas de risque de carence modéré et dans trois cas sur six dans les situations de risque de carence faible. Concernant la teneur en huile, le soufre a eu une influence positive dans quatre cas de risque de carence modéré sur neuf et aucun effet sur les cas de risque faible. Cette méthode de prévision du risque doit permettre aux agriculteurs d'optimiser la fumure soufrée du colza d'automne sans en pénaliser la qualité.The experimental results of four growing seasons (1999-2002) were analysed to im-prove a prediction model of sulphur deficiency for winter oilseed rape previously pre-sented in the «DBF 2001» (RYSER et al., 2001). This scoring model based on agrono-mic pedologic and climatic criteria explained 85% of yield variability in response to sulphur fertilisation. In order of importance, the parameters of the model were soil depth, clay content, organic matter and plant-available nitrogen. Moreover, rainfall between October to March, stone content and frequency of organic fertiliser applica-tions were also taken into account. The risk of deficiency was divided into 3 catego-ries. The threshold for low risk was set at a score of 24 points and no S fertilisation was required for oilseed rape grown at low risk sites. The optimum S application of the medium risk with a score from 15 to 23 points was determined at 35 kg S/ha. The high risk of deficiency (score under 15 points) was not represented in the experiment but a proposition of fertilisation as high as 60 kg S/ha has been made. The effects of S fertilisation on total S uptake in the aerial biomass and quality of the harvested grains were also evaluated. A significant increase of total S uptake in response to S fertilisa-tion was observed. Besides, the glucosinolates concentration in the grains also increa-sed significantly with S application for all cases of moderate risk and for 3 out of 6 cases at low risk sites. Finally, sulphur had a positive influence on seed oil content of 4 out of 9 cases of moderate risk and no effect on the low risk sites.Die Resultate von Schwefeldüngungsversuchen über eine Periode von vier Jahren (1999-2002) dienten der Verbesserung einer Methode zur Abschtzung des Risikos für Schwefelmangel bei Winterraps. Diese wurden in den G•undlagen put- Düngungs-planutig im Acket-bau und Futterbau vorgestellt (RYSER et al., 2001). Mit dieser Methode zur Risikoabschützung, welche auf agronomischen, pedolo-gischen und klimatischen Kriterien beruht, konnten 85% der Variabilitüt des Ertrages als Folge der Schwefeldüngung erklürt werden. Die wichtigsten Parameter bei der Verteilung der Risikopunkte geordnet nach ihrer Bedeutung waren die Tiefgründigkeit des Bodens, der Tongehalt des Bodens in %, die organische Substanz und der verfüg-bare Stickstoff. Weitere berücksichtigte Parameter waren die Niederschlüge von Okto-ber bis Mürz, der Gehalt an Steinen und die Hüufigkeit der Hofdüngeranwendung. Das Risiko für Schwefelmangel wurde in drei Kategorien eingeteilt. Die Schwelle für ein geringes Risiko wurde bei 24 Punkten festgelegt. In dieser Kategorie wird keine Schwefeldüngung empfohlen. Für den Bereich mit einem mittleren Risiko (15-23 Punkte) wurde eine optimale Schwefeldüngung von 35 kg/ha ermittelt. Die Kategorie mit einem hohen Risiko für Schwefelmangel « 15 Punkte) war in den Versuchen nicht vertreten. Hier wurde eine empfohlene Schwefelgabe von 60 kg /ha festgelegt. Die Schwefeldüngung führte zu einer signifikant hôheren Aufnahme dieses Nühr-stoffes durch die Pflanzen. Zudem war der Glucosinolatgehalt in den Samen als Folge der Schwefeldüngung in allen Versuchen mit einem mittleren Risiko für Schwefel-mangel und in 3 von 6 Versuchen mit einem geringen Risiko signifikant hôher. Der Oelgehalt wurde in 4 von 9 Versuchen mit mittleren Mangelrisiko positiv beeinflusst, wdhrend der Oelgehalt in den Versuchen mit geringen Risiko nicht erhôht wurde. Diese Methode zur Abschützung des Risikos für Schwefelmangel ermbglicht den Landwirten eine gezielte Schwefeldüngung von Winterraps

Screening of sugar beet pre-breeding populations and breeding lines for resistance to Ditylenchus dipsaci penetration and reproduction

Ditylenchus dipsaci is an economically important plant-parasitic nematode affecting European sugar beets. To date, no sugar beet cultivars carrying resistance against D. dipsaci are available to farmers. To find potentially resistant sugar beet lines restricting reproduction and penetration of D. dipsaci, three consecutive in vivo bioassays were carried out. The first experiment determined the penetration rate of D. dipsaci in 79 breeding lines and 14 pre-breeding populations. Based on these results, D. dipsaci penetration and reproduction resistance of eight genotypes was intensively investigated. It could be demonstrated that none of the genotypes showed resistance towards D. dipsaci. However, a high variation of the penetration rate by D. dipsaci was observed among the genotypes. The breeding line ‘DIT_119’ effectively reduced D. dipsaci penetration (34.4 ± 8.8 nematodes/plant at 22 days post-planting) compared to the susceptible control (109.0 ± 16.9) while ensuring a yield comparable to non-inoculated plants. However, the breeding line ‘DIT_119’ did not reduce D. dipsaci reproduction. The paternal line of the cultivar BERETTA KWS, demonstrating a high tolerance to D. dipsaci crown rot symptoms, did not reduce penetration and reproduction. Thus, no correlation can be established between reduced penetration rates, reproduction, and tolerance to D. dipsaci. This study provides an essential basis for the development of resistant sugar beet cultivars to D. dipsaci. The variations observed among genotypes now need to be confirmed with larger-scale screenings

Potential for acrylamide formation in potatoes: data from the 2003 harvest

Reducing sugars, free amino acids, and the potential for acrylamide formation were determined in more than 50 potato samples from the 2003 harvest in Switzerland. The reducing sugar content strongly correlated with acrylamide, whereas no correlation was found between acrylamide and free asparagine or the pool of free amino acids. The reducing sugar contents and the acrylamide potentials were higher in most of the cultivars tested than in the samples from 2002. This was probably due to the hot and dry summer of 2003. Monitoring sugars and amino acids during heating at 120°C and 180°C showed that glucose and fructose reacted much faster than sucrose and the amino acids. Glutamine was consumed to a larger extent than any of the other amino acids. During prolonged storage, the reducing sugars decreased considerably while only moderate changes in the free amino acids were observed. Altogether, glucose and fructose remain the critical factors for acrylamide formation in potatoes and represent the most feasible way of reducing the formation of acrylamide in potato product

All-Cause Mortality and Causes of Death in the Swiss Hepatitis C Cohort Study (SCCS).

With direct-acting antiviral agents (DAAs), mortality rates and causes of death among persons with hepatitis C virus (HCV) infection may change over time. However, the emergence of such trends may be delayed by the slow progression of chronic hepatitis C. To date, detailed analyses of cause-specific mortality among HCV-infected persons over time remain limited. We evaluated changes in causes of death among Swiss Hepatitis C Cohort Study (SCCS) participants from 2008 to 2016. We analyzed risk factors for all-cause and cause-specific mortality, accounting for changes in treatment, fibrosis stage, and use of injectable drugs over time. Mortality ascertainment was completed by linking lost-to-follow-up participants to the Swiss Federal Statistical Office death registry. We included 4700 SCCS participants, of whom 478 died between 2008 and 2016. The proportion of unknown causes of death decreased substantially after linkage, from 42% to 10%. Leading causes of death were liver failure (crude death rate 4.4/1000 person-years), liver cancer (3.4/1000 person-years), and nonliver cancer (2.8/1000 person-years), with an increasing proportion of cancer-related deaths over time. Cause-specific analysis showed that persons with sustained virologic response were less at risk for liver-related mortality than those never treated or treated unsuccessfully. Although the expected decrease in mortality is not yet observable, causes of death among HCV-infected persons have evolved over time. With the wider use of DAAs, liver-related mortality is expected to decline in the future. Continued monitoring of cause-specific mortality will remain important to assess the long-term effect of DAAs and design effective interventions

Diagnosis and management of antiretroviral-therapy failure in resource-limited settings in sub-Saharan Africa: challenges and perspectives.

Despite the enormous progress made in scaling up antiretroviral therapy (ART) in sub-Saharan Africa, many challenges remain, not least of which are the identification and management of patients who have failed first-line therapy. Less than 3% of patients are receiving second-line treatment at present, whereas 15-25% of patients have detectable viral loads 12 months or more into treatment, of whom a substantial proportion might have virological failure. We discuss the reasons why virological ART failure is likely to be under-diagnosed in the routine health system, and address the current difficulties with standard recommended second-line ART regimens. The development of new diagnostic tools for ART failure, in particular a point-of-care HIV viral-load test, combined with simple and inexpensive second-line therapy, such as boosted protease-inhibitor monotherapy, could revolutionise the management of ART failure in resource-limited settings