A Review of Sooty Blotch and Flyspeck Disease in German Organic Apple Production

Sooty blotch and flyspeck (SBFS) fungi colonise the surface of a range of fruits, especially apple, without penetrating the cuticle. Economic damage results from the exclusion of severely affected fruit batches from being marketed as table apples. A study of SBFS was conducted in 2007–2012 in the two largest German apple production areas, i.e. the Lake Constance and Lower Elbe regions. The absence of this disease complex from orchards under integrated pest management in both regions in all years was explained by the collateral effects of scab and storage-rot sprays with captan and quinone-outside inhibitors (QoI) such as trifloxystrobin. However, SBFS was economically relevant in organically managed orchards, being generally more severe in Southern Germany than in the North. In both regions, Peltaster cerophilus was the most frequently isolated SBFS fungus and was chiefly responsible for crop losses. Cyphellophora sessilis, Microcyclosporella mali and Schizothyrium pomi also contributed to SBFS in some organic orchards, whereas a diversity of additional species was confined to untreated orchards. Evidence was obtained that P. cerophilus overwinters within orchards, fruit mummies being one of presumably several colonised plant organs. Infections of young apple fruits were initiated at any time following the end of flowering, and P. cerophilus was capable of causing several infection cycles per season by means of conidial inoculum. The colonisation of sheets of waxed paper by P. cerophilus indicated that this species does not require fruit leachates for growth. No further expansion of colonies was observed during cold storage; instead, P. cerophilus was gradually displaced by other fungi. Differences in the susceptibility of apple varieties to P. cerophilus were due to fruit ripening, late-maturing cultivars being most heavily colonised, and to surface properties, varieties with a waxy bloom being conspicuously less strongly colonised than others. This fungus was unable to colonise russeted fruit areas. Repeated spray treatments with lime-sulphur and potassium bicarbonate throughout the season were effective and necessary to control SBFS in organic production. This strategy threatens the fungicide-saving potential offered by scab-resistant apple varieties. Cultural measures against SBFS include summer pruning as well as the manual removal of fruit mummies in winter.     

Dissolved and colloidal phosphorus fluxes in forest ecosystems—an almost blind spot in ecosystem research

Understanding and quantification of phosphorus (P) fluxes are key requirements for predictions of future forest ecosystems changes as well as for transferring lessons learned from natural ecosystems to croplands and plantations. This review summarizes and evaluates the recent knowledge on mechanisms, magnitude, and relevance by which dissolved and colloidal inorganic and organic P forms can be translocated within or exported from forest ecosystems. Attention is paid to hydrological pathways of P losses at the soil profile and landscape scales, and the subsequent influence of P on aquatic ecosystems. New (unpublished) data from the German Priority Program 1685 “Ecosystem Nutrition: Forest Strategies for limited Phosphorus Resources” were added to provide up‐to‐date flux‐based information. Nitrogen (N) additions increase the release of water‐transportable P forms. Most P found in percolates and pore waters belongs to the so‐called dissolved organic P (DOP) fractions, rich in orthophosphate‐monoesters and also containing some orthophosphate‐diesters. Total solution P concentrations range from ca. 1 to 400 µg P L^?1, with large variations among forest stands. Recent sophisticated analyses revealed that large portions of the DOP in forest stream water can comprise natural nanoparticles and fine colloids which under extreme conditions may account for 40–100% of the P losses. Their translocation within preferential flow passes may be rapid, mediated by storm events. The potential total P loss through leaching into subsoils and with streams was found to be less than 50 mg P m^?2 a^?1, suggesting effects on ecosystems at centennial to millennium scale. All current data are based on selected snapshots only. Quantitative measurements of P fluxes in temperate forest systems are nearly absent in the literature, probably due to main research focus on the C and N cycles. Therefore, we lack complete ecosystem‐based assessments of dissolved and colloidal P fluxes within and from temperate forest systems.     

Trawl fishing impacts on the status of seabed fauna in diverse regions of the globe

Bottom trawl fishing is a controversial activity. It yields about a quarter of the world's wild seafood, but also has impacts on the marine environment. Recent advances have quantified and improved understanding of large‐scale impacts of trawling on the seabed. However, such information needs to be coupled with distributions of benthic invertebrates (benthos) to assess whether these populations are being sustained under current trawling regimes. This study collated data from 13 diverse regions of the globe spanning four continents. Within each region, we combined trawl intensity distributions and predicted abundance distributions of benthos groups with impact and recovery parameters for taxonomic classes in a risk assessment model to estimate benthos status. The exposure of 220 predicted benthos‐group distributions to trawling intensity (as swept area ratio) ranged between 0% and 210% (mean = 37%) of abundance. However, benthos status, an indicator of the depleted abundance under chronic trawling pressure as a proportion of untrawled state, ranged between 0.86 and 1 (mean = 0.99), with 78% of benthos groups > 0.95. Mean benthos status was lowest in regions of Europe and Africa, and for taxonomic classes Bivalvia and Gastropoda. Our results demonstrate that while spatial overlap studies can help infer general patterns of potential risk, actual risks cannot be evaluated without using an assessment model that incorporates trawl impact and recovery metrics. These quantitative outputs are essential for sustainability assessments, and together with reference points and thresholds, can help managers ensure use of the marine environment is sustainable under the ecosystem approach to management.     

Bioindication and modelling of atmospheric deposition in forests enable exposure and effect monitoring at high spatial density across scales

Key message

Moss surveys provide spatially dense data on environmental concentrations of heavy metals and nitrogen which, together with other biomonitoring and modelling data, can be used for indicating deposition to terrestrial ecosystems and related effects across time and areas of different spatial extension.

Context

For enhancing the spatial resolution of measuring and mapping atmospheric deposition by technical devices and by modelling, moss is used complementarily as bio-monitor.

Aims

This paper investigated whether nitrogen and heavy metal concentrations derived by biomonitoring of atmospheric deposition are statistically meaningful in terms of compliance with minimum sample size across several spatial levels (objective 1), whether this is also true in terms of geostatistical criteria such as spatial auto-correlation and, by this, estimated values for unsampled locations (objective 2) and whether moss indicates atmospheric deposition in a similar way as modelled deposition, tree foliage and natural surface soil at the European and country level, and whether they indicate site-specific variance due to canopy drip (objective 3).

Methods

Data from modelling and biomonitoring atmospheric deposition were statistically analysed by means of minimum sample size calculation, by geostatistics as well as by bivariate correlation analyses and by multivariate correlation analyses using the Classification and Regression Tree approach and the Random Forests method.

Results

It was found that the compliance of measurements with the minimum sample size varies by spatial scale and element measured. For unsampled locations, estimation could be derived. Statistically significant correlations between concentrations of heavy metals and nitrogen in moss and modelled atmospheric deposition, and concentrations in leaves, needles and soil were found. Significant influence of canopy drip on nitrogen concentration in moss was proven.

Conclusion

Moss surveys should complement modelled atmospheric deposition data as well as other biomonitoring approaches and offer a great potential for various terrestrial monitoring programmes dealing with exposure and effects.

     

Determination of irritant threshold concentrations to weeds,trees and grasses through serial dilutions in intradermal testing on healthy clinically nonallergic dogs

Irritant threshold concentration (ITC) for intradermal testing (IDT) was determined in 31 healthy, clinically nonallergic dogs. Twenty‐three allergens were tested at five variable concentrations ranging from 1000 to 8000 PNU/mL. To distinguish irritant reactions from subclinical IgE‐mediated hypersensitivities, serum allergy testing was performed. ITCs were determined by evaluating the lowest concentration to which no dogs (0% cut‐off) and to which at least 10% of dogs (≥10% cut‐off) reacted. ITCs at the 0% cut‐off were: 1000 PNU/mL (Johnson grass), 2000 PNU/mL (Ash, Lamb’s Quarter and Bermuda), 3000 PNU/mL (Bahia, Rye, Pig Weed and Virginia Oak), 4000 PNU/mL (Marsh Elder and Maple), 5000 PNU/mL (Sorrel sheep) and 7000 PNU/mL (Cocklebur and Black Willow). ITC for Dog Fennel, Box Elder and Red Cedar was <1000 PNU/mL. ITCs at the ≥10% cut‐off were: 2500 PNU/mL (Johnson), 3000 PNU/mL (Box Elder), 5000 PNU/mL (Bahia), 6000 PNU/mL (Pigweed and Marsh Elder) and 8000 PNU/mL (Virginia Oak and Black Willow). For all other allergens, the ITC was >8000 PNU/mL and could not be determined. No significant agreement between positive values was found for the same allergen on IDT and serum allergy testing for each dog suggesting reactions caused by the determined ITCs are less likely subclinical IgE‐mediated reactions. These results suggest that ITCs may vary, also they may be very high for the allergens tested and that higher test concentrations may be used for IDT for the tested allergens without inducing an irritant reaction. Further studies are needed to evaluate the benefit of higher IDT concentrations in atopic dogs.     

Ten-year regeneration responses to varying levels of overstory retention in two productive southern British Columbia ecosystems

We investigated survival and growth responses of planted and advance natural regeneration species of varying shade tolerance to partial retention harvesting in moist warm Interior Cedar-Hemlock (ICHmw2) and dry cool Montane Spruce (MSdk) ecosystems of southeastern British Columbia, Canada. Treatments included three levels of overstory basal area retention (none, light (∼25%), or heavy (∼50%)) installed by two harvest methods (handfelled or a pushover falling technique being tested for its ability to control the spread of root disease). After 10 years, growth of both planted and natural regeneration species of varying shade tolerance tended to increase with decreasing overstory retention and associated increases in light availability. In contrast, significant survival responses to retention level were lacking except in the case of shade-intolerant western larch. Harvest method had a variable effect on regeneration survival and growth. Where significant responses did occur, they were generally attributed to harvesting effects on the characteristics of planting microsites rather than root disease spread. Natural regeneration densities at the ICHmw2 site were high at all retention levels, whereas stocking was less consistent at the MSdk site. We concluded that moderately shade-tolerant to shade-tolerant interior spruce and western redcedar can, under conditions similar to those of our study sites, be successfully established under overstories of up to approximately 25 m²/ha basal area, but that growth performance is likely to be significantly lower than in clearcuts. Despite early survival issues, conclusions regarding Douglas-fir were similar. Poorer survival and vigour of shade-intolerant western larch suggested this species is not suitable for regeneration in partial retention systems where timber production is the primary objective. Where non-timber objectives predominate, survival and acceptable growth of even a small proportion of larch could add to the diversity of the regenerating stand.     

Heavy Metals Removal in a Horizontal Rotating Tubular Bioreactor

Mixed microbial culture was isolated from heavy metal-contaminated ground soils located inside iron, vinyl and cement factory area. Isolated mixed microbial culture was used for the heavy metal ions (Fe²⁺, Cu²⁺, Ni²⁺ and Zn²⁺) removal process in horizontal rotating tubular bioreactor (HRTB). In this research, the effect of bioreactor process parameters on the bioprocess dynamics in the HRTB was studied. Results of this research have shown that profiles of heavy metals concentration were gradually reduced along HRTB at all combinations of bioreactor process parameters [inflow rates (0.5?C2.0 L?h^-1) and rotation speed (5?C30 min^-1)]. Hydrodynamic conditions and biomass sorption capacity have main impact on the metal ions removal efficiency that was varied in the range of 38.1% to 95.5%. Notable pH gradient (cca 0.7 pH unit) along the HRTB was only observed at the inflow rate of 2.0 L?h^-1. On the basis of obtained results, it is clear that medium inflow rate (F) has higher impact on the heavy metal removal process than bioreactor rotation speed (n) due to the fact that increase of inflow rate was related to the reduction of equilibrium time for all examined metal ions. Furthermore, equilibrium times for all metal ions are significantly shorter than medium residence times at all examined combinations of bioreactor process parameters. The main impact on the biofilm sorption capacity has covalent index of metal ions and biofilm volumetric density. The sorption capacity of suspended microbial biomass is closely related to its concentration. Results of this research have also shown that the removal of heavy metals ion can be successfully conducted in an HRTB as a one-step process.     

Analysis of the Mycosporine-Like Amino Acid (MAA) Pattern of the Salt Marsh Red Alga Bostrychia scorpioides

This study presents the validation of a high-performance liquid chromatography diode array detector (HPLC-DAD) method for the determination of different mycosporine-like amino acids (MAAs) in the red alga Bostrychia scorpioides. The investigated MAAs, named bostrychines, have only been found in this specific species so far. The developed HPLC-DAD method was successfully applied for the quantification of the major MAAs in Bostrychia scorpioides extracts, collected from four different countries in Europe showing only minor differences between the investigated samples. In the past, several Bostrychia spp. have been reported to include cryptic species, and in some cases such as B. calliptera, B. simpliciuscula, and B. moritziana, the polyphyly was supported by differences in their MAA composition. The uniformity in the MAA composition of the investigated B. scorpioides samples is in agreement with the reported monophyly of this Bostrychia sp.     

Comparison of methods to quantify loss of hydraulic conductivity in Norway spruce

? Percent loss of hydraulic conductivity (PLC) is an important measure in plant water relations, but the available methods differ and results have rarely been compared.

? We compared PLC measured in Norway spruce (Picea abies) by quantifying conductivity before and after removing emboli, either by flushing with high water pressure or by infiltration under a partial vacuum, with relative water loss and staining conductive xylem to test advantages and possible problems of commonly applied methods.

? Infiltration removed nearly all gas from sections of drought-stressed and unstressed twigs, and flushing and infiltration efficiently removed emboli. Infiltration appears less prone to producing clogged xylem elements than high pressure flushing. Relative water loss (RWL) and the proportion of xylem stained with phloxine B (PSX) was also highly correlated with PLC, the latter can be quantified by image analysis, and also shows the pattern of xylem dysfunction. Loss of conductivity was more common in the inner annual rings, in early wood within an annual ring, and in compression wood, though pattern differed substantially between branches.

? Advantages and potential problems of these methods are discussed and it is suggested that RWL or PSX may be used as proxy measures for PLC in species when the correlations have been established.