Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Microbiome dynamics of disease suppresive soils
    Gómez Expósito, Ruth - \ 2017
    Wageningen University. Promotor(en): F.P.M. Govers; J.M. Raaijmakers, co-promotor(en): J. Postma; I. de Bruijn. - Wageningen : Wageningen University - ISBN 9789463431774 - 267
    suppressive soils - soil suppressiveness - plant diseases - thanatephorus cucumeris - microbial ecology - soil microbiology - rhizosphere bacteria - soil bacteria - community ecology - soil fungi - transcriptomics - taxonomy - ziektewerende gronden - bodemweerbaarheid - plantenziekten - thanatephorus cucumeris - microbiële ecologie - bodemmicrobiologie - rizosfeerbacteriën - bodembacteriën - gemeenschapsecologie - bodemschimmels - transcriptomica - taxonomie

    Disease suppressive soils are soils in which plants do not get diseased from plant pathogens due to the presence (and activities) of the microbes present in the soil. Understanding which microbes contribute to confer suppression and through which mechanisms they can protect plants is crucial for a sustainable control of plant diseases. In the research conducted in this thesis, I first examined the role of Lysobacter species, previously associated with disease suppressive soils, in suppressing damping-off disease caused by the soil-borne fungal pathogen Rhizoctonia solani on sugar beet. The majority of the Lysobacter strains tested revealed a broad metabolic potential in producing a variety of enzymes and secondary metabolites able to suppress R. solani in vitro. However, any of these strains could consistently suppress damping-off disease when applied in soil bioassays. Their ability to promote plant growth was also tested for sugar beet, cauliflower, onion or Arabidopsis thaliana. Results indicated that any of the Lysobacter strains could consistently promote plant growth, neither via direct contact nor via volatile production. Second, I investigated whether the antagonistic activity of Lysobacter species could be triggered when applied as bacterial consortia, together with Pseudomonas and Streptomyces species. Although several bacterial combinations showed an increased antagonistic effect towards R. solani in vitro, no consistent effects were observed when these bacterial consortia were applied in vivo. Third, I investigated the dynamical changes in the bacterial community composition and functions occurring during the process of disease suppressiveness induction by performing whole community analyses using next-generation sequencing techniques. Results indicated that suppressiveness induction was most associated with changes in certain bacterial traits rather than changes in the bacteria community composition itself. Among the functions found as more active in suppressive soils were several ‘classic’ mechanisms of disease suppression, including competition for nutrients, iron and space and production of extracellular enzymes, indol-acetic-acid and hydrogen cyanide. Among the enzymes found in higher abundance in suppressive soil were these ones involved in the degradation of oxalic acid, a pathogenicity factor produced by pathogenic fungi to help infecting the host plant. Hence, I finally studied the role of bacteria able to produce enzymes able to degrade oxalic acid in suppressing R. solani disease. Enrichment of native oxalotrophic bacteria existing in soil, their isolation and further application into soil revealed that they could effectively suppress Rhizoctonia disease. Characterization of these oxalotrophic bacteria revealed that members within the Caulobacter and Nocardioides species could suppress R. solani disease by their own. Furthermore, the research done in this thesis highlights the importance of combining different techniques to unravel the mechanisms underlying disease suppression and the importance of studying function-over-phylogeny. Additionally, it also highlights the importance of organic amendments (such as oxalic acid) directly into soils in order to “engineer” the bacterial functions towards the control of diseases caused by R. solani.

    Volatile-mediated interactions in the rhizosphere
    Cordovez da Cunha, Viviane - \ 2016
    Wageningen University. Promotor(en): Francine Govers; Jos Raaijmakers, co-promotor(en): V.J. Carrion. - Wageningen : Wageningen University - ISBN 9789462579019 - 219
    rhizosphere bacteria - rhizosphere fungi - microbial interactions - volatile compounds - suppressive soils - actinobacteria - streptomyces - microbacterium - thanatephorus cucumeris - growth stimulators - biological control - defence mechanisms - genomics - transcriptomics - rizosfeerbacteriën - rizosfeerschimmels - microbiële interacties - vluchtige verbindingen - ziektewerende gronden - actinobacteria - streptomyces - microbacterium - thanatephorus cucumeris - groeistimulatoren - biologische bestrijding - verdedigingsmechanismen - genomica - transcriptomica

    Plants and microorganisms are constantly engaged in highly dynamic interactions both above- and belowground. Several of these interactions are mediated by volatile organic compounds (VOCs), small carbon-based compounds with high vapor pressure at ambient temperature. In the rhizosphere, VOCs have an advantage in intra- and interorganismal signaling since they can diffuse through soil pores over longer distances than other metabolites and are not dependent on water availability. The research described in this PhD thesis explored how beneficial and pathogenic microorganisms that live in the rhizosphere and endosphere modulate plant growth, development and resistance via the production of VOCs. In vitro and in vivo bioassays as well as different ‘omic’ approaches, such as volatomics, transcriptomics and genomics, were employed to investigate underlying mechanisms of VOC-mediated microbe-microbe and microbe-plant interactions.

    To investigate the diversity and functions of microbial VOCs, a disease-suppressive soil was used as the source of the VOC-producing microorganisms. Previous metagenomics studies reported Actinobacteria, in particular Streptomyces and Microbacterium species, as the most abundant bacterial genera found in a soil naturally suppressive to the fungal root pathogen Rhizoctonia solani. VOCs of several Streptomyces isolates inhibited hyphal growth of R. solani and in addition, promoted plant growth. Coupling the Streptomyces VOC profiles with their effects on fungal growth pinpointed methyl 2-methylpentanoate and 1,3,5-trichloro-2-methoxy benzene as antifungal VOCs. Also Microbacterium isolates showed VOC-mediated antifungal activity and plant growth promotion. VOC profiling of Microbacterium sp. EC8 revealed several sulfur-containing compounds and ketones such as dimethyl disulfide, trimethyl trisulfide and 3,3,6-trimethylhepta-1,5-dien-4-one (also known as Artemisia ketone). Genome analysis of strain EC8 revealed genes involved in sulfur metabolism. Resolving the role of the identified compounds and genes in VOC-mediated plant growth promotion and induced resistance will be subject of future studies. VOC-mediated chemical warfare underground has been proposed as a key mechanism of natural disease-suppressive soils. The results presented in this thesis indeed point in that direction. However, to more conclusively determine the role of the identified Actinobacterial VOCs in soil suppressiveness to R. solani, it will be important to demonstrate that the fungicidal VOCs are actually produced in situ at the right place and at sufficient concentrations to suppress plant infection by the pathogenic fungus.

    In agriculture, VOCs and VOC-producing microorganisms provide a potential alternative to the use of pesticides to protect plants and to improve crop production. In the past decades, several in vitro studies have described the effects of microbial VOCs on other (micro)organisms. However, little is still known on the potential of VOCs in large-scale agriculture and horticulture. The results described in this thesis show that VOCs from Microbacterium sp. EC8 stimulate the growth of Arabidopsis, lettuce and tomato, but do not control damping-off disease of lettuce caused by R. solani. Significant biomass increases were also observed for plants exposed only shortly to the bacterial VOCs prior to transplantation of the seedlings to soil. These results indicate that VOCs from strain EC8 can prime plants for growth promotion without direct contact and prolonged colonization. Furthermore, the induction of the plant growth-promoting effects appeared to be plant tissue specific. Root exposure to the bacterial VOCs led to a significant increase in plant biomass whereas shoot exposure did not result in significant biomass increase of lettuce and tomato seedlings. Genome-wide transcriptome analysis of Arabidopsis seedlings exposed to VOCs from this bacterium showed an up-regulation of genes involved in sulfur and nitrogen metabolism and in ethylene and jasmonic acid signaling. These results suggest that the blend of VOCs of strain EC8 favors, in part, the plant’s assimilation of sulfate and nitrogen, essential nutrients for plant growth, development and also resistance.

    Similar to beneficial microorganisms, plant pathogenic microorganisms have also evolved strategies to modulate growth and defense of their hosts. For instance, compounds secreted by pathogens may suppress or interfere with plant defense. In this thesis I show that R. solani produces an array of VOCs that promote growth, accelerate development, change VOC emission and reduce insect resistance of plants. Plant growth-promoting effects induced by the fungal VOCs were not transgenerational. Genome-wide transcriptome analysis of Arabidopsis seedlings revealed that exposure to fungal VOCs caused up-regulation of genes involved in auxin signaling, but down-regulation of genes involved in ethylene and jasmonic acid signaling. These findings suggest that this soil-borne pathogen uses VOCs to predispose plants for infection by stimulating lateral root formation and enhancing root biomass while suppressing defense mechanisms. Alternatively, upon perception of VOCs from soil-borne pathogens, plants may invest in root biomass while minimizing investments in defense, a trade-off that helps them to speed up growth and reproduction and to survive pathogen attack.

    In conclusion, the research presented in this thesis shows that both plants and microorganisms engage via VOCs in long-distance interactions and that beneficial and pathogenic soil microorganisms can alter plant physiology in different ways. Here, I provided a first step in identifying microbial genes involved in the regulation of biologically active VOCs as well as candidate plant genes involved in VOC perception and signal transduction. How plants sense and differentiate among VOCs from beneficial and pathogenic soil microorganisms will be an intriguing subject for future studies.

    Rhizoctonia solani in potatoes and its control : Specific recommendations for seed production in Punjab (India)
    Brink, L. van den; Wustman, R. - \ 2014
    Lelystad : PPO AGV - 25
    thanatephorus cucumeris - plantenziekteverwekkende schimmels - plantenziektebestrijding - gewasbescherming - ziektebestrijdende teeltmaatregelen - pootaardappelen - aardappelen - akkerbouw - punjab (india) - india - solanum tuberosum - thanatephorus cucumeris - plant pathogenic fungi - plant disease control - plant protection - cultural control - seed potatoes - potatoes - arable farming - punjab (india) - india - solanum tuberosum
    During visits of Wageningen UR researchers to potato production fields in Punjab (India) in 2013 and 2014, it appeared that many plant had severe incidences of Rhizoctonia solani. Rhizoctonia has become a serious problem in the Punjab seed production system. This report summarizes information on Rhizoctonia and its control.
    Oligotrophic bacteria and root disease suppression in organically managed soils
    Senechkin, I.V. - \ 2013
    Wageningen University. Promotor(en): Ariena van Bruggen, co-promotor(en): Leo van Overbeek. - Wageningen : Wageningen University - ISBN 9789461738035 - 141
    bodempathogenen - plantenziekteverwekkers - thanatephorus cucumeris - fusarium oxysporum - bodembacteriën - bodembeheer - biologische landbouw - linum usitatissimum - vlas - modellen - bodemweerbaarheid - soilborne pathogens - plant pathogens - thanatephorus cucumeris - fusarium oxysporum - soil bacteria - soil management - organic farming - linum usitatissimum - flax - models - soil suppressiveness

    The objective of this thesis was to obtain a better understanding of soil health in terms of microbial and chemical characteristics as well as suppression of soil borne plant pathogens. Organic soils were chosen as an appropriate model for studying soil health. Four different organic amendments were applied on two experimental fields with different crop history, providing a diverse range of soil quality levels. Many soil microbial variables were measured, including copiotrophic and oligotrophic bacterial populations, the abundance and diversity of Eubacteria, Alphaproteobacteria, Pseudomonas and fungal communities, as well as several microbial genes involved in nitrogen cycling. Plant disease suppressiveness was used as a quantitative integrative parameter reflecting the health status of soils. Rhizoctonia solani on beet and Fusarium oxysporum on flax were selected as pathosystems; areas under disease progress curves were measured in bioassays with differentially amended field soils and were related to soil parameters. Combined rather than single amendments enhanced Fusarium suppression, but Rhizoctonia suppression was more related to crop history than organic amendments. No universal correlations were found between disease suppression and microbial and chemical parameters, although pH and organic matter affected microbial communities and Fusarium wilt. A significant relation between ammonia oxidizing bacteria and disease suppression was observed for both pathogens; this relation was likely indirect via nitrogen availability and pH. No direct relationship was found between quantities of N cycling genes and disease suppression. A specific emphasis was put on the potential role of oligotrophic bacteria in soil health and disease suppression. Bacteria isolated on low carbon medium (10 mg C/L) were repeatedly transferred onto this medium to select true oligotrophic bacteria. Most isolates could grow on both low carbon and higher carbon (1000 mg C/L) media and belonged to Streptomyces, Rhizobium, Bradyrhizobium and Mesorhizobium. A new oligotrophic isolate was identified as Collimonas sp. IS343 and its interaction with R. solani was studied. This strain was better adapted to oligotrophic conditions than a copiotrophic Collimonas reference strain and was more effective in controlling R. solani. This thesis provided a better understanding of some aspects of soil health and emphasized the role of oligotrophic bacteria, a poorly understood but very important group of soil inhabitants.

    Stimulering van ziektewering in de bodem door toevoegen van reststromen : 'Cash from trash' : eindrapport SKB-Duurzame ontwikkeling ondergrond project 2031
    Postma, J. ; Schilder, M.T. ; Hanse, B. ; Hendrickx, W. ; Venhuizen, A. - \ 2013
    Wageningen : Plant Research International Wageningen UR, Business Unit Agrosystems (Rapport / Plant Research International 529) - 46
    bodemweerbaarheid - plantenziekten - bodemschimmels - thanatephorus cucumeris - nuttige organismen - lysobacter - reststromen - digestaat - beta vulgaris - suikerbieten - solanum tuberosum - aardappelen - daucus carota - penen - keukenkruiden - nederland - veldproeven - akkerbouw - soil suppressiveness - plant diseases - soil fungi - thanatephorus cucumeris - beneficial organisms - lysobacter - residual streams - digestate - beta vulgaris - sugarbeet - solanum tuberosum - potatoes - daucus carota - carrots - culinary herbs - netherlands - field tests - arable farming
    Dit rapport bevat de resultaten van twee jaar onderzoek naar praktijktoepasbare methoden om de ziektewering in de bodem tegen Rhizoctonia solani, een belangrijke gewasbelager, te verhogen. Het huidige SKB project is gestart om goedkope effectieve reststoffen te identificeren en te zoeken naar een voor de praktijk toepasbare methode om ziektewering in de bodem te verhogen.
    Beheersing van Rhizoctonia solani door verhoogde bodemweerbaarheid
    Postma, J. ; Hanse, B. ; Schilder, M.T. - \ 2013
    Gewasbescherming 44 (2013)3. - ISSN 0166-6495 - p. 83 - 84.
    bodemweerbaarheid - thanatephorus cucumeris - bodemschimmels - lysobacter - veldproeven - landbouwkundig onderzoek - gewasbescherming - soil suppressiveness - thanatephorus cucumeris - soil fungi - lysobacter - field tests - agricultural research - plant protection
    In de afgelopen jaren is uitgebreid gezocht naar een methodiek die wel de ziektewering tegen Rhizoctonia betrouwbaar kan stimuleren. Hierbij is ontdekt dat de antagonistische bacteriegroep Lysobacter spp., die van nature in diverse Nederlandse gronden voorkomt, correleert met ziektewering. In 2012 zijn voor het eerst veldproeven uitgevoerd.
    De rol van Collimonas sp. 343 in de onderdrukking van Rhizotonia solani AG2 onder nutriëntenlimitering in de bodem
    Overbeek, L.S. van; Senechkin, I.V. ; Er, H.L. ; Vos, O.J. de; Bruggen, A.H.C. van - \ 2012
    Gewasbescherming 43 (2012)4. - ISSN 0166-6495 - p. 128 - 128.
    bodempathogenen - thanatephorus cucumeris - bodemweerbaarheid - bodembiologie - bodembacteriën - wetenschappelijk onderzoek - gewasbescherming - soilborne pathogens - thanatephorus cucumeris - soil suppressiveness - soil biology - soil bacteria - scientific research - plant protection
    Onder bepaalde omstandigheden, zoals behandelingen met verschillende soorten organische stof, zijn bodems weerbaarder tegen Rhizoctonia solani. De vraag is wat het mechanisme achter deze verhoogde weerbaarheid is en de hypothese van de onderzoekers is dat de levende fractie van de bodem hier voor verantwoordelijk is.
    Bestrijding Rhizoctonia solani in zomerbloemen
    Bulle, A.A.E. ; Breeuwsma, S.J. - \ 2012
    Lisse : PPO Bloembollen en Bomen - 20
    zomerbloemen - rassen (planten) - plantenziekteverwekkende schimmels - thanatephorus cucumeris - bodemschimmels - chemische bestrijding - alternatieve methoden - toelating van bestrijdingsmiddelen - landbouwkundig onderzoek - summer flowers - varieties - plant pathogenic fungi - thanatephorus cucumeris - soil fungi - chemical control - alternative methods - authorisation of pesticides - agricultural research
    Rhizoctonia solani (dradenschimmel) is een bodemschimmel die in veel zomerbloemgewassen ernstige schade kan veroorzaken. Jonge scheuten worden vanuit de grond door de schimmel aangetast. Aangetaste planten worden geel, blijven achter in groei en sterven vervolgens af. In onder andere Astilbe, Alchemilla, Delphinium, Aconitum, Paeonia en Helianthus kan de schimmel veel schade aanrichten. Voor de chemische bestrijding van R. solani werd tot nu toe het middel Rizolex (tolclofos-methyl) gebruikt. Sinds 2009 heeft het middel geen reguliere toelating meer in de onbedekte teelt van zomerbloemen. In 2010 kon men Rizolex nog gebruiken op basis van een Dringend Vereiste Toelating (DVT), maar deze DVT kon niet meer worden verlengd. Op korte termijn is behoefte aan andere middelen voor de bestrijding van R. solani in zomerbloemen. Het doel van dit onderzoek is een alternatief te vinden voor het middel Rizolex voor de bestrijding van R. solani in zomerbloemen.
    Bestrijding van Rhizoctonia solani in zomerbloemen
    Bulle, A.A.E. ; Slootweg, G. - \ 2011
    fungiciden - thanatephorus cucumeris - zomerbloemen - plantenziekteverwekkende schimmels - bodempathogenen - vollegrondsteelt - fungicides - thanatephorus cucumeris - summer flowers - plant pathogenic fungi - soilborne pathogens - outdoor cropping
    Poster met informatie over onderzoek naar alternatieve gewasbeschermingsmiddelen voor Rizolex tegen Rhizoctonia solani in zomerbloemen.
    Beoordeling van aardappelknollen op lakschurft (Rhizoctonia): het vaststellen van de Sclerotiënindex
    PPO Akkerbouw, Groene Ruimte en Vollegrondsgroente, - \ 2011
    PPO AGV
    aardappelen - sclerotia - thanatephorus cucumeris - aantasting - potatoes - sclerotia - thanatephorus cucumeris - infestation
    In dit document wordt aangegeven hoe bepaald wordt in welke mate aardappelknollen bezet zijn met lakschurft. In een monster van voorzichtig gewassen aardappelknollen wordt iedere knol ingedeeld in een aantastingsklasse, variërend van schoon tot zwaar aangetast. Op basis van de aantallen in de verschillende klassen wordt de sclerotiënindex berekend.
    Detectie van Lysobacter spp. in de bodem; het dilemma van te veel of te weinig meten
    Postma, J. ; Schilder, M.T. - \ 2010
    Gewasbescherming 41 (2010)1. - ISSN 0166-6495 - p. 12 - 12.
    detectie - plantenziekteverwekkende bacteriën - thanatephorus cucumeris - onderzoek - technieken - dna - ziektepreventie - detection - plant pathogenic bacteria - thanatephorus cucumeris - research - techniques - dna - disease prevention
    Onderzoek van de afgelopen jaren heeft aangetoond dat de aanwezigheid van de antagonistische bacterie Lysobacter correleert met ziektewering in bodems tegen Rhizoctonia solani-aantasting. Het betreft de nauw verwante soorten L. antibioticus, L. capsici en L. gummosus. Voor verder onderzoek naar stimulering van deze antagonistische Lysobacter-soorten in de bodem zijn detectietechnieken nodig, zodat de invloed van teeltmaatregelen op de populatieomvang van Lysobacter bepaald kan worden
    Bodemweerbaarheidstoets voor Rhizoctonia solani
    Postma, J. ; Schilder, M.T. - \ 2009
    Gewasbescherming 40 (2009)2. - ISSN 0166-6495 - p. 81 - 82.
    proeven op proefstations - biotesten - biologische technieken - thanatephorus cucumeris - ziektedistributie - akkerbouw - bodemweerbaarheid - vollegrondsteelt - station tests - bioassays - biological techniques - thanatephorus cucumeris - disease distribution - arable farming - soil suppressiveness - outdoor cropping
    Reeds vele jaren wordt de bodemweerbaarheidstoets die door Pedro Oyarzun werd ontwikkeld met succes toegepast om de ziektewering van verschillende bodems tegen Rhizoctonia solani met elkaar te vergelijken. Deze toets wordt onder gestandaardiseerde condities uitgevoerd in een klimaatcel. Alle gronden worden bij een gelijke vochtspanning (pF 1,7 = -50 mbar) getoetst
    Ziektewering van bodemgebonden pathogenen en functionele diversiteit van de bodemmicroflora
    Schilder, M.T. ; Postma, J. - \ 2009
    Gewasbescherming 40 (2009)1. - ISSN 0166-6495 - p. 23 - 23.
    gewasbescherming - bodembiologie - thanatephorus cucumeris - streptomyces - verticillium - streptomyces scabiei - suikerbieten - raphanus - brassica napus - bodemweerbaarheid - bodempathogenen - bodemmicrobiologie - plant protection - soil biology - thanatephorus cucumeris - streptomyces - verticillium - streptomyces scabiei - sugarbeet - raphanus - brassica napus - soil suppressiveness - soilborne pathogens - soil microbiology
    Dit onderzoek richt zich op het vinden van micro-organismen of hun eigenschappen die correleren met ziektewering op verschillende bedrijfstypen en grondsoorten.
    Biotoetsen als een van de mogelijkheden om bodemgezondheid te meten en te begrijpen
    Korthals, G.W. ; Visser, J.H.M. - \ 2009
    Gewasbescherming 40 (2009)2. - ISSN 0166-6495 - p. 78 - 79.
    biotesten - biologische technieken - experimenteel veldonderzoek - compost - groenbemesters - bodembiologie - grondbewerking - organische stof - thanatephorus cucumeris - akkerbouw - bodempathogenen - biologische grondontsmetting - vollegrondsteelt - bioassays - biological techniques - field experimentation - composts - green manures - soil biology - tillage - organic matter - thanatephorus cucumeris - arable farming - soilborne pathogens - biological soil sterilization - outdoor cropping
    In het onderzoek komt steeds meer aandacht voor aspecten die te maken hebben met algehele bodemgezondheid. Er zijn verschillende grote projecten, zoals de Bodemgezondheidsproef te Vredepeel, waarbij geprobeerd wordt om de Bodemgezondheid te verbeteren. Binnen WUR zijn inmiddels verschillende biotoetsen ontwikkeld. In ons veldonderzoek zijn verschillende biotoetsen gebruikt om in het veld extra waarnemingen te kunnen doen aan de effectiviteit van verschillende maatregelen
    Organische stof en ziektewering in de sierteelt
    Os, G.J. van; Bent, J. van der; Conijn, C.G.M. - \ 2009
    Gewasbescherming 40 (2009)1. - ISSN 0166-6495 - p. 22 - 22.
    gewasbescherming - organische stof - zandgronden - biotesten - meloidogyne hapla - pratylenchus penetrans - pythium - thanatephorus cucumeris - narcissus - tulipa - hyacinthus - sierteelt - bodemkwaliteit - plant protection - organic matter - sandy soils - bioassays - meloidogyne hapla - pratylenchus penetrans - pythium - thanatephorus cucumeris - narcissus - tulipa - hyacinthus - ornamental horticulture - soil quality
    Resultaten uit lopend onderzoek naar de effecten van organische stof op de bodemkwaliteit van duinzandgrond en de haalbaarheid van geïntegreerde en biologische teelten met een gewasrotatie van 1:7 met bolgewassen, heesters en vaste planten
    Moleculaire en biochemische analyse van antagonistische bacteriën betrokken bij bodemgebonden ziektewering tegen Rhizoctonia solani
    Kruijt, M. ; Pangesti, N. ; Wagemakers, L. ; Raaijmakers, J. - \ 2008
    Gewasbescherming 39 (2008)supplement. - ISSN 0166-6495 - p. 35S - 36S.
    gewasbescherming - thanatephorus cucumeris - plantenziektebestrijding - ziektebestrijdende teeltmaatregelen - bodembacteriën - schimmelantagonisten - biopesticiden - bodemkwaliteit - plant protection - thanatephorus cucumeris - plant disease control - cultural control - soil bacteria - fungal antagonists - microbial pesticides - soil quality
    Soil suppressiveness and functional diversity of soil microflora in organic farming systems
    Postma, J. ; Schilder, M.T. ; Speksnijder, A.G.C.L. - \ 2008
    biologische landbouw - bodemflora - schimmelziekten - thanatephorus cucumeris - streptomyces scabiei - verticillium dahliae - bodemweerbaarheid - organic farming - soil flora - fungal diseases - soil suppressiveness
    Arable fields of 10 organic farms from different locations within the Netherlands were sampled in four subsequent years. The soil samples were analysed for disease suppressiveness against Rhizoctonia solani, Streptomyces scabies and Verticillium dahliae. Furthermore, a variety of microbial characteristics and chemical and physical soil properties were assessed. All these characteristics and different environmental factors were correlated by multivariate analyses. Significant differences in soil suppressiveness were found for all three diseases. Suppressiveness against Rhizoctonia was more or less consistent between the sampled fields in 2004 and 2005. This suppressiveness correlated with higher numbers of Lysobacter and Pseudomonas antagonists, as well as fungal diversity in DGGE patterns. Furthermore, results of 2006 showed that one year of grass-clover clearly stimulated Rhizoctonia suppression. Also Streptomyces soil suppressiveness was consistent between 2004 and 2005, but it concerned other soils than the ones which were suppressive against Rhizoctonia. Streptomyces suppression correlated with higher numbers of antagonists in general, Streptomyces and the fungal/bacterial biomass ratio, but with a lower organic matter content and respiration. Soil suppressiveness against Verticillium was not consistent between the years and therefore probably not related to soil factors.
    Streptomyceten-diversiteit in grond met behulp van DGGE
    Schilder, M.T. ; Postma, J. - \ 2008
    Gewasbescherming 39 (2008)1. - ISSN 0166-6495 - p. 28 - 28.
    streptomyces - diversiteit - thanatephorus cucumeris - grondanalyse - onderzoek - bodembacteriën - afbraak (plantenziektekundig) - organische stof - bodempathogenen - bodemweerbaarheid - wetenschappelijk onderzoek - streptomyces - diversity - thanatephorus cucumeris - soil analysis - research - soil bacteria - breakdown - organic matter - soilborne pathogens - soil suppressiveness - scientific research
    Streptomyceten vormen een belangrijke groep bacteriën in de bodem. Ze spelen een grote rol bij de afbraak van organische stof. Bovendien is aangetoond dat ze correleren met ziektewering van verschillende bodempathogenen
    Gaatjes in consumptieaardappelen : bureaustudie naar optreden en beheersing
    Wustman, R. - \ 2007
    Kennisakker.nl 2007 (2007)15 juni.
    aardappelen - consumptieaardappelen - oogstschade - elateridae - thanatephorus cucumeris - akkerbouw - plantenplagen - plantenziekten - potatoes - table potatoes - crop damage - elateridae - thanatephorus cucumeris - arable farming - plant pests - plant diseases
    Gaatjes in consumptieaardappelen (tafel- en verwerkingsaardappelen) zijn soms een belangrijk kwaliteitsprobleem in Nederland. Doel van deze bureaustudie was een beschrijving van de mogelijke oorzaken. Rhizoctonia solani en ritnaalden werden genoemd als belangrijkste veroorzakers van gaatjes. De belangrijkste probleemgebieden zijn op lichte gronden in bouwplannen met gescheurd grasland, graszaad of groenbemesters.
    Grondbesmetting gekoppeld aan teeltfrequentie
    Lamers, J.G. - \ 2007
    BioKennis bericht Akkerbouw & vollegrondsgroenten 2 (2007). - 4
    aardappelen - thanatephorus cucumeris - besmetting - microbiële besmetting - bodem - vermeerderingsmateriaal - controle - antagonisten - akkerbouw - maatregelen - potatoes - thanatephorus cucumeris - contamination - microbial contamination - soil - propagation materials - control - antagonists - arable farming - measures
    Rhizoctonia in de aardappel kan veel schade veroorzaken. Schade zowel door opbrengstverlaging als door kwaliteitsverlies. Om schade te beperken zijn er verschillende beheersmaatregelen mogelijk. Met behulp van het puntensysteem van Lamers kan eenvoudig bepaald worden hoe groot het risico op schade is. Ook is daarmee snel te zien welke maatregelen getroffen kunnen worden om het risico op schade te verminderen.
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