Evolution of Qol resistance in <Emphasis Type="Italic">Plasmopara viticola</Emphasis> oospores

QoI resistance in P. viticola was first detected in France and Italy in 1999. Molecular and biological assays have been carried out since 2000 in order to provide reliable methods of detecting and quantifying resistance. Oospores were collected in vineyards located in northern and southern Italy. QoI resistance was evaluated by the germination rate of oospores on azoxystrobin amended medium and the frequency of mutant alleles in the DNA extracted from oospores. Both methods correlated to each other and were used side by side to test QoI resistance. Due to the spontaneous occurrence of the G143A mutation in wild type populations and the immigration from surrounding vineyards, resistance frequencies up to 10% were found in samples collected from vineyards never treated with QoIs. Particularly high values, about 90%, were associated with the application of five to six QoI treatments within the same season, while lower percentages, about 30%, were detected in vineyards treated with QoI used in mixture with fungicides belonging to a different resistance group. A progressive decrease of resistance frequency was observed when QoI applications were reduced in number or completely suspended for at least one season. Therefore, a full recovery of sensitivity may be achieved even in vineyards characterized by high levels of resistance, if particular care is taken during disease control by using QoIs only in mixtures and reducing the number of QoI treatments.     

Testing Snow Mould Resistance of Winter Wheat: Inoculation Experiments with Microdochium nivale in the Field

Winter survival of 24 winter wheat lines was evaluated at three locations in south-eastern Norway in 1996-97 and 1997-98. Plants were inoculated with a mycelial suspension of Microdochium nivale or a preparation of M. nivale mycelium grown on boiled wheat grains, or they remained uninoculated. Artificially applied inoculum led to a higher disease pressure in some of the trials only. The effect of environmental conditions on variation in winter survival among wheat lines was greater than that of inoculation, and it was therefore difficult to draw a definite conclusion on the variation in specific snow mould resistance.     

Mediterranean moisture source for an early-Holocene humid period in the northern Red Sea

Paleosalinity and terrigenous sediment input changes reconstructed on two sediment cores from the northernmost Red Sea were used to infer hydrological changes at the southern margin of the Mediterranean climate zone during the Holocene. Between approximately 9.25 and 7.25 thousand years ago, about 3 per thousand reduced surface water salinities and enhanced fluvial sediment input suggest substantially higher rainfall and freshwater runoff, which thereafter decreased to modern values. The northern Red Sea humid interval is best explained by enhancement and southward extension of rainfall from Mediterranean sources, possibly involving strengthened early-Holocene Arctic Oscillation patterns and a regional monsoon-type circulation induced by increased land-sea temperature contrasts. We conclude that Afro-Asian monsoonal rains did not cross the subtropical desert zone during the early to mid-Holocene.     

Impact of grass silage quality on greenhouse gas emissions from dairy and beef production

High‐quality grass silages may represent a mitigation option by reducing enteric methane production and by increasing productivity, thus reducing greenhouse gas emissions per kg of product (emission intensity). Two previous studies found considerable effects of three different silage qualities cut at different maturity stages (very early [H1], early [H2] and normal [H3]) offered ad libitum with various levels of concentrate supplementation, on animal performances of growing/finishing bulls and dairy cows in early lactation, indicating that emission intensities may also vary. Based on results from these previous studies, the aim of this study was to estimate emission intensities for milk and beef carcasses for the included combinations of silage qualities and concentrate levels, by using the farm‐scale model HolosNor. The emissions intensities were lowest for the H1 silage, and highest for the H3 silage, independent of concentrate levels for both milk and beef. Thus, increasing concentrate levels did not compensate for lower grass silage quality. Improvements in silage quality from H3 silage to H2 is realistic and has the potential to reduce emission intensities with approximately 10% while keeping the milk yield per cow constant and reducing the use of concentrates considerably. For beef production, the potential is even larger, with a reduction in emission intensity of approximately 17%. We conclude that improving grass silage quality may be a mitigation option that will also reduce the dependence on concentrates.     

Correspondence of the fine-scale spatial variation in soil chemistry and the herb layer vegetation in beech forests

The objective of this paper is to analyse the degree to which the variation in soil conditions corresponds to the occurrence of specific plant species at micro-scale. The investigation was performed in beech forests with seven plant species growing on three sites with different geological substrates of the Triassic period (Muschelkalk, Oberer and Mittlerer Buntsandstein). At each site three to five plant species of ca. 20 individuals each were selected by stratified random sampling. The growth location of a plant individual was considered to be a potential microsite. At the gowth locations, soil solution was exctracted in situ by low tension lysimetry from the rooted topsoil exactly beneath the selected plant individuals. A soil sample was taken from the same spot and analysed for pH(H₂O) and exchangeable cations. In addition, the vegetation was recorded around each target individual and species composition was related to chemical soil properties by multivariate analyses.

The three sites were found to form a gradient with respect to most analysed soil parameters. Variation coefficients of soil properties increased in the sequence pH, exchangeable Ca, K, Mg, Al, Fe, Mn. Concentrations of cations in the soil solution varied to a higher degree than those of exchangeable cations with the sole exception of Fe that showed a lower variation in the soil solution. Averaged over all sites, the microsite values for pH and exchangeable Ca exhibited a distinct sequence for the investigated species with decreasing values in the root horizon in the sequence Mercurialis perennis, Arum maculatum, Lamiastrum galeobdolon, Galium odoratum, Viola reichenbachiana, Oxalis acetosella and Luzula luzuloides. Within sites, only few significant differences were found between the potential microsites of specific species. The microsites of species on Muschelkalk differed in pH, concentrations of exchangeable Ca and K and of Ca in the soil solution. The microsites on Mittlerer Buntsandstein differed in pH and concentration of exchangeable Fe. No significant differences between species were found on Oberer Buntsandstein. Species composition in a area of 3.14 m² around the sample locations varied only to a minor degree as was revealed by canonical correspondence analysis (CCA). In addition, the low level of encountered variation could only be explained to a small degree by the soil variables.

It is concluded that the analysed environmental factors are of minor importance for fine-scale species occurrences. At a scale of meters or less, biotic parameters might exert a greater influence than soil parameters.     

Household Biowaste Containers (Bio-Bins) – Potential Incubators For Clostridium Botulinum and Botulinum Neurotoxins

In previously conducted research, Clostridium botulinum spores were found in bio-waste compost. Household bio-waste, collected in `bio-bins', was suspected to be one of the reasons for contamination. Maggots of Calliphoridae were collectedinside and outside of bio-bins from 8 different locations in central Germany and examined for C. botulinum toxin and/orbacterial forms using standard mouse bioassay. Young maggots (instar 1) contained neither C. botulinum nor toxin, but these were found in instar 2 and 3 larvae. For the first time these results show that fly larvae out of bio-bins are not onlya nuisance, but may be vectors of the potentially lethal C.botulinum.     

The formation of maghemite and hematite from lepidocrocite and goethite in a Cambisol from Corsica,France

The influence of a recent forest fire on the iron oxide phases, present in the A and the B horizon of a brown earth from Corsica, was examined by X-ray diffraction and chemical analysis. In the B horizon goethite and lepidocrocite, in the A horizon maghemite and hematite were identified. From the Al/(Al+Fe) ratio, which was determined for all four minerals by XRD, it was concluded that goethite was the precursor of hematite and lepidocrocite the precursor of maghemite respectively. The proportion of maghemite formed in the A horizon was calculated from the difference in Fe_d between the untreated sample and that free of maghemite. Because of substantial dissolution of clay minerals even after 5 citrate-bicarbonate treatments, it was not possible to determine Al_d correctly.     

Influence of the Atlantic subpolar gyre on the thermohaline circulation

During the past decade, record-high salinities have been observed in the Atlantic Inflow to the Nordic Seas and the Arctic Ocean, which feeds the North Atlantic thermohaline circulation (THC). This may counteract the observed long-term increase in freshwater supply to the area and tend to stabilize the North Atlantic THC. Here we show that the salinity of the Atlantic Inflow is tightly linked to the dynamics of the North Atlantic subpolar gyre circulation. Therefore, when assessing the future of the North Atlantic THC, it is essential that the dynamics of the subpolar gyre and its influence on the salinity are taken into account.