Pathogenicity of <Emphasis Type="Italic">Stemphylium vesicarium</Emphasis> from different hosts causing brown spot in pear     

Jürgen Köhl  Belia Groenenboom-de Haas  Helen Goossen-van de Geijn  Adrianus Speksnijder  Pieter Kastelein  Sybren de Hoog  Bert Gerrits van den Ende 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(1):151-162

Stemphylium vesicarium (teleomorph: Pleospora herbarum) is the causal agent of brown spot disease in pear. The species is also able to cause disease in asparagus, onion and other crops. Saprophytic growth of the fungus on plant debris is common. The objective of this study was to investigate whether isolates of S. vesicarium from different hosts can be pathogenic to pear. More than hundred isolates of Stemphylium spp. were obtained from infected pear fruits, dead pear leaves, dead grass leaves present in pear orchard lawns as well as from necrotic leaf parts of asparagus and onion. Only isolates originating from pear orchards, including isolates from dead grass leaves, were pathogenic on pear leaves or fruits in bioassays. Non-pathogenic isolates were also present in pear orchards. Stemphylium vesicarium from asparagus or onion, with one exception, were not pathogenic to pear. Analysis of the genetic variation between isolates using Amplified Fragment Length Polymorphism (AFLP) showed significant concordance with host plants. Isolates from asparagus or onion belonged to clusters separate from the cluster with isolates from pear or grass leaves collected in pear orchards. Multilocus sequencing of a subset of isolates showed that such isolates were similar to S. vesicarium.  相似文献   

Surface‐applied insecticide treatments for quarantine control of Japanese beetle,Popillia japonica Newman (Coleoptera: Scarabaeidae), larvae in field‐grown nursery plants     

Jason B Oliver  Michael E Reding  Nadeer N Youssef  Michael G Klein  Bert L Bishop  Phil A Lewis 《Pest management science》2009,65(4):381-390

BACKGROUND: Japanese beetles, Popillia japonica Newman, are a quarantine challenge for nursery shipments from infested to non‐infested states. Marathon (imidacloprid) and Discus (imidacloprid + cyfluthrin) are approved preharvest nursery treatments (US Domestic Japanese Beetle Harmonization Plan; DJHP). This study evaluated approved and non‐approved (acephate, carbaryl, clothianidin, dinotefuran, halofenozide, thiamethoxam, trichlorfon) preharvest treatments, optimal rates (labeled 1×, 0.3–0.75× or 2–3×) and optimal timings (June, July, August and September) to control early‐instar (grubs) P. japonica in field nurseries. RESULTS: Most insecticides effectively reduced grub densities, except for acephate, carbaryl and trichlorfon. Clothianidin, thiamethoxam and halofenozide provided grub control equivalent to DJHP standards during most years. Across all test years and timings, percentage grub reductions were: Marathon (1×: 59.2–100; 3×: 78.9–100), Discus (1×: 60.7–100), clothianidin (1×: 96.1–100; 3×: 97.4–100), thiamethoxam (1×: 75.0–100; 3×: 80.0–100), halofenozide (1×: 70.0–100; 3×: 90.0–100) and dinotefuran (1×: 13.2–88.2; 3×: 71.1–93.4). CONCLUSIONS: July application was more consistent and effective than other timings, and higher rates (2× and 3×) did not generally improve grub control. Overall, clothianidin, thiamethoxam and halofenozide (and dinotefuran applied in August) were equivalent to current DJHP standards. These insecticides may be suitable for DJHP Category 2 states, potentially lowering grower costs. Copyright © 2009 Society of Chemical Industry  相似文献   

Material properties determining the insecticidal activity of highly divided porous materials on the pharaoh ant (Monomorium pharaonis)          下载免费PDF全文

Heleen Van Den Noortgate  Bert Lagrain  Sreeprasanth Pulinthanathu Sree  Stef Kerkhofs  Tom Wenseleers  Johan A Martens 《Pest management science》2018,74(6):1374-1385

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<Emphasis Type="Italic">Aphelenchoides gorganensis</Emphasis> n. sp. (Nematoda: Aphelenchoididae)<Emphasis Type="Italic">,</Emphasis> a new species from Iran     

Esmaeil Miraeiz  Ramin Heydari  Wim Bert 《European journal of plant pathology / European Foundation for Plant Pathology》2017,147(1):157-166

Phytophthora capsici infection of chili pepper seedlings can cause substantial losses due to damping-off and collar rot diseases. Chemical control is no longer effective due to reported resistance development, on top of the related environmental concerns and the consumer demands for reduced use of fungicides. Biological control is a sustainable option, with several agents having been reported to be effective against this pathogen. This research focused on optimizing the application of strain THSW13 of Trichoderma hamatum and a bacterial isolate BJ10–86 with the objectives of improving chili pepper seed germination, reduce damping-off disease incidence, and improve the growth of the seedlings. Bacterial isolate BJ10–86 was subjected to molecular identification and found to be Pseudomonas aeruginosa. Chili pepper seeds treated with the biocontrol agents, individually or in combination, were seeded into commercial nursery media that had been pre-inoculated with P. capsici zoospores. Over a period of 35 days the chili pepper seed treatments significantly (P = 0.008) reduced the disease incidence of seedlings damping-off. Combined application of T. hamatum and P. aeruginosa was the best biocontrol treatment with an area under disease curve of only 36.61 units compared to 92.87 units for the control treatment. Similar results were observed in vitro where T. hamatum and P. aeruginosa synergistically inhibited P. capsici growth by 73.2 %. The inhibition activity of this treatment was similar to mefenoxam treatment, which implies that it is an effective and sustainable alternative for chili pepper seed treatment. The biocontrol seed treatment had no effect on seed germination and seedling growth.  相似文献   

The impact of redox agents on sugar-snap cookie making     

Bram Pareyt  Bénédicte Van SteertegemKristof Brijs  Bert LagrainJan A. Delcour 《Journal of Cereal Science》2010

The impact of the oxidants potassium bromate and potassium iodate and the reducing agents L-cysteine, glutathione and sodium metabisulfite on sugar-snap cookie making was investigated. Spread behavior of cookie dough during baking (spread rate, set time and collapse) was monitored and texture properties of the baked cookies were determined. Low levels of redox agents impacted neither dough nor cookie properties. High levels of reducing agents (10,000 ppm on a flour base) significantly decreased set time, and, hence, cookie diameter. They also decreased the degree of collapse, which then, evidently, also increased cookie height. Earlier setting and higher resistance to structural collapse, but also the higher intrinsic break strength of the cookie material when adding high levels of reducing agents could be explained on a molecular level as resulting from earlier and more pronounced gliadin–glutenin cross-linking. In contrast, when high levels of oxidizing agents were added, a postponed setting, a more pronounced collapse and decreased intrinsic cookie break strength were observed. The present work demonstrates the importance of heat-induced gluten polymerization during cookie baking and confirms that free sulfhydryl groups are necessary for the polymerization reactions. A model illustrating the role of gluten cross-linking during cookie making is put forward.  相似文献   

Fate of vinclozolin,thiabendazole and dimethomorph during storage,handling and forcing of chicory     

Pieter Spanoghe  Bert Ryckaert  Cindy Van Gheluwe  Marie‐Christine Van Labeke 《Pest management science》2010,66(2):126-131

BACKGROUND: As part of ongoing research for a sustainable production of Belgian endives, the fate of three fungicides during storage, handling and forcing of witloof chicory roots was investigated. Storage roots are protected against Sclerotinia sp. Fuckel and Phoma exigua var. exigua Desm. by means of vinclozolin and thiabendazole respectively. During hydroponic forcing, the most imminent pathogen is Phytophthora cryptogea Pethybr. & Laff., which is controlled by the use of dimethomorph. RESULTS: Vinclozolin and thiabendazole concentrations on roots remained constant during storage at ?1 °C. Dermal exposure of the workers in hydroponics was exceeded. Vinclozolin and thiabendazole residues were not detected 2 weeks after hydroponic forcing; dimethomorph was still detected at harvest. At harvest, the vinclozolin concentration in the chicory heads was below the maximum residue limit, but the chicory roots contained residues much above the thiabendazole and dimethomorph maximum residue level. CONCLUSION: Vinclozolin and thiabendazole residues applied before storage are still present on the roots at the start of the forcing cycle. During the set‐up of chicory roots, preventive measures are recommended, as effects of repeated human exposure to low doses of applied fungicides cannot be excluded. Dimethomorph applied at the start of the hydroponic forcing is the only pesticide detected in the drainage water at harvest. The chicory heads were safe for human consumption. However, more attention should be paid to the residues of fungicides in the roots used for cattle feeding. Copyright © 2009 Society of Chemical Industry  相似文献   

Organic carbon sequestration in earthworm burrows     

Axel Don  Bert Steinberg  Ingo Schöning  Karin Pritsch  Monika Joschko  Gerd Gleixner  Ernst-Detlef Schulze 《Soil biology & biochemistry》2008,40(7):1803-1812

Earthworms strongly affect soil organic carbon cycling. The aim of this study was to determine whether deep burrowing anecic earthworms enhance carbon storage in soils and decrease C turnover. Earthworm burrow linings were separated into thin cylindrical sections with different distances from the burrow wall to determine gradients from the burrow wall to the surrounding soil. Organic C, total N, radiocarbon (¹⁴C) concentration, stable isotope values (δ¹³C, δ¹⁵N) and extracellular enzyme activities were measured in these samples. Anecic earthworms increased C stocks by 270 and 310 g m^?2 accumulated in the vertical burrows. C-enrichment of the burrow linings was spatially highly variable within a distance of millimetres around the burrow walls. It was shown that C accumulation in burrows can be fast with C sequestration rates of about 22 g C m^?2 yr^?1 in the burrow linings, but accumulated C in the burrows may be mineralised fast with turnover times of only 3–5 years. Carbon stocks in earthworm burrows strongly depended on the earthworm activity which maintains continuous C input into the burrows. The enhanced extracellular enzyme activity of fresh casts was not persistent, but was 47% lower in inhabited burrows and 62% lower in abandoned burrows. Enzyme activities followed the C concentrations in the burrows and were not further suppressed due to earthworms. Radiocarbon concentrations and stable isotopes in the burrow linings showed an exponential gradient with the youngest and less degraded organic matter in the innermost part of the burrow wall. Carbon accumulation by anecic earthworm is restricted to distinct burrows with less influence to the surrounding soil. Contrary to the initial hypothesis, that organic C is stabilised due to earthworms, relaxation time experiments with nuclear magnetic resonance spectroscopy (NMR) did not reveal any enhanced adsorption of C on iron oxides with C stabilising effect. Our results suggest that earthworm activity does not substantially increase subsoil C stocks but burrows serve as fast ways for fresh C transport into deep soil horizons.  相似文献   

Effects of iron-ore mining and processing on metal bioavailability in a tropical coastal lagoon     

Adriana Alves Pereira  Bert van Hattum  Abraham Brouwer  Peter Michiel van Bodegom  Carlos Eduardo Rezende  Wim Salomons 《Journal of Soils and Sediments》2008,8(4):239-252

Background, aim, and scope

In water systems, water quality and geochemical properties of sediments determine the speciation of trace metals, metal transport, and sediment–water exchange, influencing metal availability and its potential effects on biota. Studies from temperate climates have shown that iron-ore mining and tailing wastewaters, besides being a source of trace metals, usually show high levels of dissolved ions and particulate suspended matter, thus having the potential of indirectly changing metal bioavailability. For the first time in the tropics, we identified the effects of iron-ore mining and processing on metal bioavailability in a coastal lagoon. With an extensive sampling scheme, we investigated the potential sources of metals; the links among metal levels in water, sediments, and invertebrates; and the contrasting effects on metal speciation and bioavailability.

Methodology

The metals Fe, Mn, Al, Cr, Zn, Cu, Ni, Pb, Cd, Hg, and As were measured in water, sediments (surface and profiles), and invertebrates from Mãe-Bá Lagoon and in the sites directly influenced by the mining operations (tailing dams and nearby rivers). In addition, samples from two other lagoons, considered pristine, were analyzed. The study area is located in the southeast of Brazil (Iron Quadrangle Region and a coastal area of Espírito Santo State). General water characteristics included pH, dissolved organic carbon, alkalinity, and anion composition. Water metal speciation was assessed by a speciation model (Chemical Equilibria in Aquatic Systems). Grain-size distribution, organic carbon, carbonate, and acid volatile sulfide (AVS) were determined in sediments. Statistical methods included comparison of means by Mann–Whitney test, ordination and correlation analyses, and analysis of regression for geochemical normalization of metals with grain size.

Results and discussion

The dissolved metal concentrations, the total metal levels in sediments, and the normalization based on the fine sediment fraction showed that the mining operations constitute potential sources of Fe, Mn, Cr, Cu, Ni, Pb, As, and Hg to Mãe-Bá Lagoon. However, trace metal availability was reduced because of increased pH, hardness, and sulfide content (356 μmol/g) in the sites influenced by the mining. The lagoon showed similar water chemistry as in the mining sites, with metal bioavailability further decreased by the presence of dissolved organic carbon and chloride. Although AVS levels in the lagoon were low (0.48–56 μmol/g), metal bioavailability was reduced because of the presence of organic matter. Metal levels in invertebrates confirmed the predicted low metal bioavailability in Mãe-Bá Lagoon. The lagoon was considered moderately contaminated only by Hg and As.

Conclusions

The iron-ore mining and processing studied here constitute potential sources of metal pollution into the tropical lagoon. Contrary to expectations, however, it also contributes to reducing the overall metal bioavailability in the lagoon.

Recommendations and perspectives

These findings are believed to be useful for evaluating metal exposure in a more integrated way, identifying not only the sources of pollution but also how they can affect the components involved in metal speciation and bioavailability in water systems, leading to new insights.  相似文献   

Xylanases from microbial origin induce syrup formation in dough     

Peter De Schryver  Susana Seseña  Bert Decaigny  Tom Van de Wiele  Willy Verstraete  Nico Boon 《Journal of Cereal Science》2008

Syrup formation in refrigerated doughs is a problem since it reduces the doughs’ shelf life. Microbial exogenous xylanases associated with wheat kernels were found to play a role in this syruping phenomenon. Using xylanase-producing microorganisms isolated from wheat kernels, we investigated their potency to induce syruping in dough. Growth of the fungal xylanase producer Fusarium sp. (10² colony forming units (CFU)/g dough) and the bacterial xylanase producer Paenibacillus sp. (10⁴ CFU/g dough) in synthetic media and their respective addition to wheat dough could not bring about a significant amount of syruping. However, when these species were grown on moist wheat kernels and an extract of these kernels containing both the organisms and its xylanases was made and added to dough, intensive syruping was noted. This effect was primarily attributed to the xylanases present in the extract. These findings suggest that the involvement of xylanase-producing microorganisms in the syruping phenomenon is situated prior to harvest. Additional quantitative analyses of microbial biomass present on wheat kernels revealed that the fungi in particular could be correlated to higher microbial exogenous xylanase activities on wheat. Our results indicate that the syruping is linked to fungal xylanase production on the wheat kernels in the field.  相似文献   

Application of Oat Oil in Breadbaking     

Sofía V. Erazo‐Castrejn  Douglas C. Doehlert  Bert L. D'Appolonia 《Cereal Chemistry》2001,78(3):243-248

Lipids, especially polar lipids, can improve loaf volume, grain and texture, and delay staling in bread. Oats (Avena sativa L.) are rich in total and polar lipids. We have investigated the effect of oat lipids in a bread formulation on loaf volume, appearance, and bread staling. Oat oil was fractionated into polar and nonpolar fractions by water‐degumming. Crude oat oil and shortening (at 3%) increased loaf volume by ≈11% over the zero lipid formulation. The polar lipid fraction increased loaf volume by nearly the same amount when added at only a 0.5% level. The addition of 3% crude oat oil or 0.7% oat oil polar fraction significantly delayed bread firming and starch retrogradation; the difference between oat lipids and shortening was more evident at the end of a four‐day storage period. Oat lipids had a stronger relative effect on bread from a weak flour (10% protein) than from a strong flour (14% protein). The effects of oat oil in the bread formulation could be related to the amphipathic character of polar lipids in oats that enables them to interact with starch, proteins, and other bread components.  相似文献