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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Effect biologische grondontsmetting : gewaswaarnemingen in laanbomen
Sluis, B.J. van der; Even, S. - \ 2015
Randwijk : Praktijkonderzoek Plant & Omgeving, Business Unit Bloembollen, Boomkwekerij en Fruit (Rapport / Praktijkonderzoek Plant & Omgeving, onderdeel van Wageningen UR Business Unit Bloembollen, Boomkwekerij en Fruit 2015-21) - 15 p.
boomkwekerijen - houtachtige planten als sierplanten - biologische grondontsmetting - straatbomen - bodemschimmels - verticillium dahliae - veldproeven - groenbemesters - folie - verwelkingsziekten - forest nurseries - ornamental woody plants - biological soil sterilization - street trees - soil fungi - field tests - green manures - foil - wilts
Het doel van het project is om op een aantal percelen waarop biologische grondontsmetting (BGO) is toegepast door middel van gewaswaarnemingen het effect van BGO vast te leggen.
Biologisch redmiddel tegen verwelkingsziekte in de Boomkwekerij : kennis en ervaringen uit een praktijknetwerk
Sluis, B.J. van der; Even, S. - \ 2015
Randwijk : Praktijkonderzoek Plant & Omgeving, Business Unit Bloembollen, Boomkwekerij en Fruit - 33 p.
boomkwekerijen - houtachtige planten als sierplanten - straatbomen - rosaceae - bodemschimmels - verticillium dahliae - biologische grondontsmetting - detectie - veldproeven - verwelkingsziekten - groenbemesters - folie - forest nurseries - ornamental woody plants - street trees - soil fungi - biological soil sterilization - detection - field tests - wilts - green manures - foil
Het doel van het project is om door samenwerking tussen kwekers, loonbedrijf, onderzoek en teelt-advisering de implementatie van (duurzame) biologische grondontsmetting te stimuleren door het samen opdoen en delen van kennis hierover. Daarnaast is er behoefte aan een snelle en nauwkeurige methode voor detectie van Verticillium in grond de bodem. Deze wordt in een EU-MKB project ontwikkeld. Vanuit het praktijknetwerk zal zo mogelijk kennis uit dit project benut worden.
Insertional mutagenesis in the vascular wilt pathogen Verticillium dahliae
Santhanam, P. - \ 2014
University. Promotor(en): Bart Thomma, co-promotor(en): Pierre de Wit. - Wageningen : Wageningen University - ISBN 9789461738257 - 124
plantenziekteverwekkende schimmels - verticillium dahliae - verwelkingsziekten - insertiemutagenese - solanum lycopersicum - tomaten - modellen - pathogeniteit - genkartering - genomica - plant pathogenic fungi - wilts - insertional mutagenesis - tomatoes - models - pathogenicity - gene mapping - genomics

Vascular wilt diseases caused by soil-borne pathogens are among the most

devastating plant diseases worldwide. The ascomycete fungus Verticillium dahliae

causes vascular wilt diseases in hundreds of dicotyledonous plant species, including

important crops such as eggplant, lettuce, olive, spinach and tomato. The resting

structures, microsclerotia, are triggered by root exudates to germinate and penetrate

the roots after which the fungus grows into the xylem vessels. The fungus colonizes

these vessels and interferes with the transportation of water and nutrients, resulting in

the development of symptoms such as stunting, wilting, chlorosis and vascular

browning. Verticillium wilt diseases are difficult to control due to the longevity of the

microsclerotia, the broad host range of the pathogen, the inability of fungicides to kill

the fungus once it has colonized the xylem vessels and the lack of natural resistance in

many plant species.

Chapter 1 is the introduction to this thesis that describes the identified

pathogenicity and virulence factors of V. dahliae and strategies to identify these

components. In spite of the economic importance of V. dahliae, relatively few

pathogenicity genes have been identified in this species. With the availability of

whole genome sequences and the development of functional genomics tools such as

random mutagenesis, targeted mutagenesis, transcriptomics, RNA interference

(RNAi) and comparative genomics, more strategies have become available to identify

novel pathogenicity and virulence genes.

Chapter 2 focuses on the identification of virulence and pathogenicity genes

of V. dahliae by screening of a library of random T-DNA insertion mutants. Using

Agrobacterium tumefaciens-mediated transformation, 900 T-DNA transformants with

random insertions were generated and screened for altered virulence on susceptible

tomato plants. This screening, followed by inverse PCR on selected transformants,

resulted in the identification of 55 potential pathogenicity and virulence genes. One of

the potential pathogenicity genes, VdNRS/ER, is a homolog of a nucleotide-rhamnose

synthase/epimerase-reductase (NRS/ER), which is presumably involved in the

biosynthesis of UDP-rhamnose. Using targeted mutagenesis, VdNRS/ER was deleted

from wild-type V. dahliae and the resulting deletion mutants were characterized.

VdNRS/ER deletion mutants exhibit unaltered vegetative growth and sporulation, but

the deletion mutants were no longer pathogenic on tomato and N. benthamiana and

showed impaired root attachment on tomato seedlings. These data suggest that UDPrhamnose

is required for pathogenesis of V. dahliae.

Chapter 3 describes the role of the V. dahliae homolog of Sge1, a

transcriptional regulator that was shown to play a role in pathogenicity and regulate

effector gene expression in Fusarium oxysporum. In this chapter it is demonstrated

that V. dahliae Sge1 (VdSge1) is required for radial growth and production of asexual

conidiospores. It is furthermore shown that VdSge1 deletion strains have lost

pathogenicity on tomato. Since the VdSge1 deletion mutants are not able to infect and

colonize tomato plants, a tomato cell suspension culture was used to the study the

expression of Ave1, as well as nine other genes of which the expression is highly

induced in planta. This assay revealed that VdSge1 is not required for the induction of

the Ave1 effector that activates resistance mediated by Ve1 in tomato. Furthermore,

the expression of one other putative effector gene was not affected by VdSge1

deletion. However, VdSge1 was shown to be required for the expression of six

putative effector genes, whereas expression of the remaining two putative effectors

genes was negatively regulated. Thus, the data show that VdSge1 is required for V.

dahliae pathogenicity and differentially regulates effector gene expression.

Chapter 4 describes the functional characterization of the gene family

encoding necrosis- and ethylene-inducing-like proteins (NLPs) of V. dahliae. The

cytotoxic activity of NLP family members was determined using agroinfiltration into

tobacco leaves. This resulted in the identification of two out of the seven NLPs,

VdNLP1 and VdNLP2, that induced plant cell death. The genes encoding these

cytotoxic NLPs were found to be induced in V. dahliae upon colonization of tomato.

Targeted deletion of VdNLP1 and VdNLP2 significantly reduced the virulence of V.

dahliae on tomato and Arabidopsis plants. In contrast, only deletion of VdNLP1

affected virulence on N. benthamiana whereas deletion of NLP2 did not. However,

subsequent transcriptional analysis revealed that VdNLP2 was not expressed in V.

dahliae during colonization of N. benthamiana. Moreover, VdNLP2 also affects

vegetative growth and conidiospore production. In conclusion, the expanded V.

dahliae NLP family shows differential cytotoxic activity between family members

and in planta induction of the cytotoxic NLP genes varies between plant hosts. In

addition, VdNLP2 plays a role in vegetative growth and conidiospore production in

addition to its contribution to virulence. Thus, evidence is provided for functional

diversification within the V. dahliae NLP family.

Finally in Chapter 5, the major findings of this thesis are discussed and

placed in a broader perspective.

Cultivation and diseases of Proteaceae: Leucadendron, Leucospermum and Protea
Crous, P.W. ; Denman, S. ; Taylor, J.E. ; Swart, L. ; Bezuidenhout, C.M. ; Hoffman, L. ; Palm, M.E. ; Groenewald, J.Z. - \ 2013
Utrecht, The Netherlands : CBS-KNAW Fungal Biodiversity Centre (CBS biodiversity series 13) - ISBN 9789070351953 - 360
proteaceae - leucadendron - leucospermum - protea - snijbloemen - teelt - plantenziekten - plantenziekteverwekkende schimmels - taxonomie - identificatie - determinatietabellen - gastheerreeks - plantenziekteverwekkende bacteriën - ziektebestrijding - fytosanitair beleid - verwelkingsziekten - wortelrot - kanker (plantenziektekundig) - cut flowers - cultivation - plant diseases - plant pathogenic fungi - taxonomy - identification - keys - host range - plant pathogenic bacteria - disease control - phytosanitary policies - wilts - root rots - cankers
Proteaceae represent a prominent family of flowering plants in the Southern Hemisphere. Because of their beauty, unique appearance, and relatively long shelf life, Proteaceae cut-flowers have become a highly desirable crop for the export market. The cultivation of Proteaceae is a thriving industry that provides employment in countries where these flowers are grown, often in areas that are otherwise unproductive agriculturally. Diseases cause a loss in yield, and also limit the export of these flowers due to strict phytosanitary regulations. In this publication the fungi that cause leaf, stem and root diseases on Leucadendron, Leucospermum and Protea are treated. Data are provided pertaining to the taxonomy, identification, host range, distribution, pathogenicity, molecular characteristics and control of these pathogens. Taxonomic descriptions and illustrations are provided and keys are included to distinguish species in genera where a number of species affect Proteaceae. Disease symptoms are described and colour photographs are included. Where known, factors that affect disease epidemiology are discussed. Disease management strategies are also presented that will assist growers and advisors in making appropriate choices for reducing disease in specific areas. Information is also provided relating to crop improvement, cultivation techniques, harvesting and export considerations. Further development and expansion of this industry depends on producing and obtaining disease-free germplasm from countries where these plants are indigenous. For that reason it is important to document the fungi that occur on Proteaceae, and to establish the distribution of these fungi. These data are essential for plant quarantine services for use in risk assessments.
Verticillium : Status quo van een miljoenenverslindende bodemziekte : Kansen en oplossingen bij bestrijding en beheer van verwelkingsziekte
Hiemstra, J.A. ; Sluis, B.J. van der - \ 2013
Boom in business 4 (2013)6. - ISSN 2211-9884 - p. 20 - 23.
boomkwekerijen - houtachtige planten - sierplanten - verwelkingsziekten - verticillium - schimmelziekten - landbouwkundig onderzoek - resistentieveredeling - bestrijdingsmethoden - bodemschimmels - forest nurseries - woody plants - ornamental plants - wilts - fungal diseases - agricultural research - resistance breeding - control methods - soil fungi
Verwelkingsziekte bedreigt al jaren de boomkwekerij, m.n. in de teelt van laanbomen en rozen. Onderzoek naar deze bodemziekte is daarom hard nodig. Jelle Hiemstra en Bart van der Sluis geven in dit artikel een overview van de stand van zaken met betrekking tot onderzoek naar dit probleem.
Verticillium wilt resistance in Arabidopsis and tomato: identification and functional characterization
Yadeta, K.A. - \ 2012
University. Promotor(en): Pierre de Wit, co-promotor(en): Bart Thomma. - S.l. : s.n. - ISBN 9789461733849 - 147
solanum lycopersicum - arabidopsis thaliana - modellen - plant-microbe interacties - ziekteresistentie - verdedigingsmechanismen - verticillium - verwelkingsziekten - moleculaire plantenziektekunde - models - plant-microbe interactions - disease resistance - defence mechanisms - wilts - molecular plant pathology

Vascular wilt pathogens, which comprise bacteria, fungi and oomycetes, are among the most destructive plant pathogens that affect annual crops as well as woody perennials, thus not only impacting world food and feed production but also natural ecosystems. Vascular wilt pathogens colonize the xylem vessels of their host plants and interfere with the normal transportation of water and nutrients from the roots to upper parts of the plant, thus causing wilting symptoms. The structure and composition of xylem vessels has a significant impact on the colonization of host plants by these pathogens. Presently, genetic resistance is the most preferred control strategy against this group of plant pathogens.

Verticillium wilt disease, which is caused by the vascular fungal pathogen Verticillium spp., is among the major diseases in various horticultural crops in tropical, subtropical, and temperate agro-ecological regions. The genus Verticilllium comprises of three major plant pathogenic species; V. dahliae, V. albo-atrum,and V. longisporum. While V. dahliae and V. albo-atrum arecharacterized with the ability to infect broad host range, V. longisporum has relatively limited host range infecting mainly crucifers family. V. dahliae and V. albo-atrum isolates are categorized into race 1 and race 2 based on their ability to infect tomato plants containing a Ve1 resistance gene. On tomato, while race 1 isolates are contained by Ve1 resistance gene, race 2 isolates overcome Ve1-mediated resistance.

Chapter 1is the introduction to the thesis that describes xylem defence responses that are directed against vascular wilt pathogens. Plants recognize xylem-invading vascular wilt pathogens by using extracellular or intracellular receptors. Pathogen recognition activates innate immune responses that include physical and chemical defense responses in the xylem vessels and the surrounding parenchyma cells. While physical defense responses often halt pathogen movement between vessels, chemical defense responses can eliminate the pathogen or inhibit its growth, thereby leading to resistance.

In order to identify novel sources of Verticillium wilt resistance, a collection of activation-tagged Arabidopsis mutants was screened for plants that displayed enhanced Verticillium wilt resistance. Chapter 2 describes four mutants (A1 to A4) that showed enhanced resistance to not only V. dahliae, but also to V. albo-atrum, and the Brassicaceae pathogen V. longisporum. Further characterization of resistance in these mutants against other vascular wilt pathogens, Ralstonia solanacearum and Fusarium oxysporum f. sp. Raphani, and the foliar pathogens such Botrytis cinerea, Plectosphaerella cucumerina, Alternaria brassicicola, and Pseudomonas syringae pv. tomato, is presented in this chapter. Except for mutant A2, that showed enhanced resistance to R. solanacearum, and mutants A1 and A3, that showed enhanced susceptibility to P. syringae, all the mutants responded similar as wild-type plants to these pathogens. In chapter 2, we furthermore describe the cloning and functional characterization of the gene encoding the AT-hook DNA-binding protein AHL19 that is responsible for the enhanced resistance of the A1 mutant to Verticillium wilt disease. The Arabidopsis genome contains 29 AHL proteins (Fujimoto et al., 2004)some of which have been implicated in various biological processes including plant development (Lim et al., 2007; Xiao et al., 2009)and defense (Kim et al., 2007Kim et al., 2007; Lu et al., 2010). AHL19 provides Verticillium wilt resistance upon over-expression, whereas knock-out enhances susceptibility, indicating that AHL19 positively regulates Verticillium wilt resistance. AHL19 not only regulates Verticillium wilt resistance, but also affects plant development, as AHL19 over-expressing plants showed larger leaf size, delayed maturity, and low seed production (Yadeta et al., 2011).

Chapter 3describes the cloning and functional characterization of EVR1 (for Enhanced Verticillium Resistance 1), the gene that is responsible for the enhanced Verticillium wilt resistance in mutant A2. Mutant A2 furthermore confers resistance to the bacterial vascular wilt pathogen R. solanacearum (Yadeta et al., 2011). While EVR1 over-expression enhances Arabidopsis resistance to three vascular wilt pathogens: V. dahliae, R. solanacearum, and F. oxysporum, knock-out enhances susceptibility to V. dahliae and R. solanacearum. Furthermore, EVR1 appears to regulate drought stress resistance. EVR1 is a single copy gene that encodes a protein of unknown function, and EVR1 homologs are only found in Brassicaceae species thus far. Interestingly, over-expression of the B. oleraceae EVR1 homolog in Arabidopsis conferred Verticillium wilt resistance. Moreover, over-expression of Arabidopsis and B. oleraceae EVR1 and BoEVR1 in the Solanaceous species N. benthamiana enhanced Verticillium wilt resistance. This suggests that the Brassicaceae-specific EVR1 gene can be used to engineer Verticillium wilt resistance in other plant families.

Whereas chapters 2 and 3 focus on the identification of novel sources of Verticillium wilt resistance by screening a collection of Arabidopsis gain-of-function mutants, Chapter 4 describes the identification of novel Verticillium wilt resistance in wild tomato accessions. Six wild accessions were identified that displayed enhanced resistance to race 2 isolates. Surprisingly, however, these accessions did not show enhanced resistance to race 1 isolates. Using virus-induced gene silencing, the resistance signalling leading to race 2 resistance in the wild accessions was investigated, showing that the resistance signalling in the wild accessions is distinct from the signalling pathway employed by the resistance protein Ve1.

Finally in chapter 5, the highlights of this thesis are discussed and placed in a broader perspective.

Functional analysis of the tomato Ve resistance locus against Verticillium wilt
Fradin, E.F. - \ 2011
University. Promotor(en): Pierre de Wit, co-promotor(en): Bart Thomma. - [s.l.] : S.n. - ISBN 9789085859611 - 163
verticillium dahliae - verticillium albo-atrum - solanum lycopersicum - tomaten - ziekteresistentie - genen - resistentieveredeling - functionaalanalyse - verticale resistentie - verwelkingsziekten - tomatoes - disease resistance - genes - resistance breeding - functional analysis - vertical resistance - wilts

Verticillium dahliae, V. albo-atrum and V. longisporum are soil-borne plant pathogens that are responsible for Verticillium wilt diseases in temperate and subtropical regions. Collectively they can infect over 200 hosts, including many economically important crops. Chapter 1 is a “pathogen profile” which describes the most important aspects of the biology of the Verticillium wilt pathogens. They colonize the xylem vessels of their host plants and cause symptoms such as wilting, chlorosis, stunting, necrosis and vein clearing. Verticillium species are notoriously difficult to control as there are no fungicides available to cure plants once they are infected. Therefore, genetic resistance is the preferred method for disease control.

Chapter 2 describes the functional characterization of the tomato (Solanum lycopersicum) Ve locus. This locus is responsible for resistance against race 1 strains of V. dahliae and V. albo-atrum and comprises two closely linked inversely oriented genes, Ve1 and Ve2. Both genes encode cell surface receptor proteins of the extracellular leucine-rich repeat (eLRR) receptor-like protein (RLP) class of disease resistance proteins. In chapter 2, it is demonstrated that Ve1, but not Ve2, provides resistance in tomato against race 1 but not against race 2 strains of V. dahliae and V. albo-atrum. Using virus-induced gene silencing in tomato, the signaling cascade downstream of Ve1 was shown to require both EDS1 (enhanced disease susceptibility1) and NDR1 (non-race-specific disease resistance1). In addition, also NRC1 (NB-LRR protein required for hypersensitive response-associated cell death1), ACIF (Avr9/Cf-9–induced F-box1), MEK2 (MAP/ERK kinase2), and SERK3/BAK1 (somatic embryogenesis receptor kinase 3/brassinosteroid-associated kinase 1) act as positive regulators of Ve1 in tomato. In conclusion, Ve1-mediated resistance signaling only partially overlaps with signaling mediated by Cf proteins, type members of the eLRR-RLP-class of resistance proteins.

In chapter 3 an attempt to introduce Nicotiana benthamiana as a model to facilitate the study of Ve1-mediated resistance is described. Challenge of wild type plants with several race 1 and race 2 strains of V. dahliae and V. albo-atrum demonstrated that N. benthamiana is susceptible to both Verticillium species. To obtain Verticillium wilt resistant plants, N. benthamiana was engineered to express the tomato Ve1 coding sequence. However, out of thirteen transgenic lines, six showed clear phenotypic aberrancies that included severe stunting and malformed leaves when compared to wild type plants. The seven Ve1-transgenic lines that did not show any phenotypic alterations were challenged with race 1 and race 2 strains. Although the pathogenicity assays indicated that in few lines Ve1 expression temporarily reduced disease development, most lines were as susceptible as wild type parental line. In conclusion, in chapter 3 it is demonstrated that the Ve1-transgenic N. benthamiana lines could not be used to study Ve1-mediated resistance signaling.

In chapter 4, the use of Arabidopsis (Arabidopsis thaliana) as model to facilitate the study of Ve1-mediated resistance is presented. To this end, tomato Ve1 was expressed in susceptible Arabidopsis plants. Upon challenge with race 1 strains of V. dahliae or V. albo-atrum, Ve1-expressing plants were found to be resistant. In contrast, Ve1-expressing plants were susceptible to race 2 strains of both V. dahliae and V. albo-atrum. Furthermore, expression of Ve1 in Arabidopsis plants did not prevent colonization by V. longisporum strains. Through Ve1-expression in Arabidopsis defense signaling mutants, it was demonstrated that signaling downstream of Ve1 is highly conserved between tomato and Arabidopsis.

In previous chapters it was shown that the receptor kinase SERK3/BAK1 is required for Ve1-mediated resistance in tomato as well as in Arabidopsis. In Arabidopsis, SERK3/BAK1 belongs to a gene family consisting of five members. In chapter 5, the requirement of the different SERK family members in Ve1-mediated resistance in Arabidopsis is investigated, revealing the requirement of SERK1 and, although to a lesser extent, SERK4 for resistance. Using virus-induced gene silencing, it was subsequently shown that SERK1 is also required for Ve1-mediated resistance in tomato. In conclusion, the results of chapter 5 demonstrate that Arabidopsis can be used as model to unravel the molecular mechanisms of Ve1-mediated resistance.

In chapter 6, the recognition specificity of Ve1 was further investigated by performing domain-swaps with Ve2 and expressing the chimeric Ve proteins in Arabidopsis. Various domain swaps in which eLRRs from Ve1 were replaced by those of Ve2 suggest that the region between eLRR22 and eLRR35 is required for full Ve1-mediated resistance. However, plants expressing a Ve chimera in which eLRR1 to eLRR30 of Ve1 was replaced with those of Ve2 were resistant against Verticillium. Overall, these results suggest that Ve2 may still bind the elicitor in the eLRR domain, but its C-terminal domain is not able to activate a successful defense response.

Finally in Chapter 7, highlights of this thesis are discussed and placed in a broader perspective.

Nieuwe phytophthora speelt Pacysandra-kwekers parten
Kuik, A.J. van; Dalfsen, P. van - \ 2010
De Boomkwekerij 23 (2010)45. - ISSN 0923-2443 - p. 12 - 13.
houtachtige planten als sierplanten - pachysandra - plantenziekten - aantasting - phytophthora - plantenziekteverwekkende schimmels - verwelkingsziekten - ziektebestrijding - bedrijfshygiëne - ornamental woody plants - plant diseases - infestation - plant pathogenic fungi - wilts - disease control - industrial hygiene
In Pachysandra komt sinds enkele jaren een verwelkingsziekte voor waarvan de veroorzaker onbekend was. Uit onderzoek blijkt dat in zieke planten de pseudoschimmel te beheersen, is een goede bedrijfshygiëne.
Biologische grondontsmetting ter bestrijding van Verticillium dahliae en Meloidogyne in de biologische teelt van glasgroenten
Paternotte, S.J. ; Bloemhard, C.M.J. ; Wurff, A.W.G. van der - \ 2009
Gewasbescherming 40 (2009)5. - ISSN 0166-6495 - p. 259 - 259.
tuinbouw - kassen - teelt onder bescherming - grondsterilisatie - biologische behandeling - verticillium dahliae - meloidogyne - biologische productie - verwelkingsziekten - gewasbescherming - tomaten - capsicum - biologische grondontsmetting - glasgroenten - glastuinbouw - horticulture - greenhouses - protected cultivation - soil sterilization - biological treatment - biological production - wilts - plant protection - tomatoes - biological soil sterilization - greenhouse vegetables - greenhouse horticulture
Verticillium-verwelkingsziekte, veroorzaakt door Verticillium dahliae is een toenemend probleem in de biologische teelt van paprika. De problemen met deze ziekte nemen ook toe in (geënte) tomaten. Voortdurend telen van afwisselend paprika en tomaat resulteert in een toenemende ziektedruk in de bodem. De telers hebben beperkte mogelijkheden om gewassen te telen die geen waardplant zijn en de grond te ontsmetten, door stomen. In het verleden zijn goede bestrijdingsresultaten behaald met biologische grondontsmetting
Bruinrot bij aardappel
Janse, J.D. ; Bergsma-Vlami, M.M. ; Wenneker, M. - \ 2009
Gewasbescherming 40 (2009)4. - ISSN 0166-6495 - p. 176 - 187.
ralstonia solanacearum - plantenziekteverwekkende bacteriën - aardappelen - vermeerderingsmateriaal - verwelkingsziekten - besmetting - bestrijdingsmethoden - symptomen - ziektedistributie - wetenschappelijk onderzoek - maatregelen - diagnostiek - moleculaire diagnostiek - plant pathogenic bacteria - potatoes - propagation materials - wilts - contamination - control methods - symptoms - disease distribution - scientific research - measures - diagnostics - molecular diagnostics
De quarantaineziekte bruinrot van aardappel, veroorzaakt door de bacterie Ralstonia (voorheen : Pseudomonas solanacearum) werd in Nederland voor het eerst met zekerheid aangetroffen in 1992. Het betrof een geïsoleerd geval in Zuid-Limburg, dat later verbonden bleek te zijn met een eerder opgetreden besmetting in België. Sindsdien is door een grote inspanning van de Plantenziektenkundige Dienst (PD), de Nederlandse Algemene Keuringsdienst (NAK), het bedrijfsleven en het onderzoek (Plant Research International (PRI - voorheen IPO) en Wageningen Universiteit veel bereikt. Dit artikel geeft een overzicht van de aanpak en het onderzoek sinds de uitbraak van bruinrot in 1995 en werpt een blik vooruit naar toekomstige ontwikkelingen
Nieuwe verwelkingsziekte in Pachysandra terminalis
Dalfsen, P. van; Hollinger, T.C. ; Bohne, S. - \ 2008
Lisse : PPO Bloembollen en Bomen
verwelkingsziekten - sierteelt - pachysandra terminalis - phytophthora citrophthora - plantenziekteverwekkende schimmels - plantenziekten - wilts - ornamental horticulture - plant pathogenic fungi - plant diseases
Sinds enkele jaren komen bij enkele telers in de teelt van Pachysandra terminalis verwelkte planten voor. Ondanks ingrijpen met allerlei gewasbeschermingsmiddelen kon deze ziekte moeilijk onder controle gekregen worden. Vanwege de afwijkende symptomen was niet duidelijk welke ziekteverwekker hiervoor verantwoordelijk is.
Verticillium komt vaker voor dan we denken
Hiemstra, J.A. - \ 2003
Bomennieuws 28 (2003)4. - ISSN 0166-784X - p. 8 - 11.
verticillium dahliae - bomen - schimmels - plantenziekteverwekkende schimmels - schimmelbestrijding - schimmelziekten - verwelkingsziekten - verwelking - symptomen - schade - ziekteoverdracht - infectie - plantenziektebestrijding - levenscyclus - gewasbescherming - trees - fungi - plant pathogenic fungi - fungus control - fungal diseases - wilts - wilting - symptoms - damage - disease transmission - infection - plant disease control - life cycle - plant protection
Beschrijving van de ziektecyclus, symptomen en bestrijding van verticillium-verwelking van bomen. Verwelkingsziekte van bomen, veroorzaakt door de schimmel Verticillium dahliae, komt vaker voor dan gedacht wordt, en veroorzaakt schade in de boomteelt, aan laanbomen en aan oudere bomen in stad en landschap. Vooral de esdoorn is gevoelig. De schimmel infecteert zijn waardplanten via de wortel, wat leidt tot verstopte vaten, belemmering van het watertransport en droogteverschijnselen. Vaak wordt de ziekte bij bomen niet herkend; karakteristiek is dat de ziekte vaak eenzijdig aan een boom optreedt. De kansen op herstel variëren per boomsoort. Behandeling van zieke bomen is niet goed mogelijk. Onderzoekers van PRI en PPO-Boskoop werken aan resistente rassen en milieuvrindelijke methoden ter bestrijding van de schimmel in de bodem. Voorlopig blijft het voorkomen van een aantasting de enige effectieve bestrijding (schoon plantmateriaal op een schone bodem)
Verticillium wilt in trees. Detection, prediction and disease management
Goud, J.C. - \ 2003
University. Promotor(en): Ariena van Bruggen, co-promotor(en): Aad Termorshuizen. - [S.I.] : S.n. - ISBN 9058088723 - 98
verticillium dahliae - verwelkingsziekten - houtachtige planten als sierplanten - plantenziekteverwekkende schimmels - virulentie - bodembiologie - epidemiologie - pathogeniteit - nederland - wilts - ornamental woody plants - plant pathogenic fungi - virulence - soil biology - epidemiology - pathogenicity - netherlands

Verticillium dahliae , the causal agent of verticillium wilt, is the cause of high losses in a number of crops, especially nursery trees. Existing methods for quantification of V. dahliae microsclerotia in the soil were compared. The distinction of V. dahliae and V. tricorpus was studied on two semi-selective media. The morphology was highly dependent on the medium. Discriminating morphological characteristics were successfully used to identify isolates. There were no virulence differences on trees between the two V. dahliae VCGs that occur in the Netherlands. Biological soil disinfestation reduced V. dahliae in the soil by 85% and Pratylenchus fallax nematodes by 99%, through the creation of anaerobic conditions. The relationships between soil inoculum densities and verticillium wilt in Acer platanoides and Catalpa bignonioides showed that up to 5% diseased plants occurred at 1-2 detected microsclerotia per g soil. Diseased plants often recovered, but had a higher chance of becoming diseased again.

Verticillium en siergewassen : DWK 364 'innovatie in siergewassen' : rapport deelproject 1.1 'ketenstudies'
Hiemstra, J.A. - \ 2001
Wageningen : Plant Research International - 15
sierplanten - verticillium - plantenziekteverwekkende schimmels - plantenziekten - verwelkingsziekten - economische drempels - ziektebestrijding - nederland - houtachtige planten als sierplanten - ornamental plants - ornamental woody plants - plant pathogenic fungi - plant diseases - wilts - economic thresholds - disease control - netherlands
Toetsing van verschillende herkomsten van es op vatbaarheid voor essenverwelkingsziekte
Schuring, W. ; Schaaf, K. van der - \ 1999
Nederlands Bosbouwtijdschrift 71 (1999)1. - ISSN 0028-2057 - p. 25 - 28.
verticillium dahliae - fraxinus excelsior - verwelking - verwelkingsziekten - plantenziekteverwekkende schimmels - plantenziekten - schimmelziekten - vatbaarheid - rassenproeven - herkomstproeven - oorsprong - wilting - wilts - plant pathogenic fungi - plant diseases - fungal diseases - susceptibility - variety trials - provenance trials - origin
De aardappel is waardplant voor de essenverwelkingsziekte (Verticillium dahliae Klehbahn); dit is van belang bij het bebossen van landbouwgronden. Door IBN-DLO is onderzocht hoe plantmateriaal van verschillende herkomsten van Fraxinus excelsior (twee inheems en twee formeel goedgekeurde rassen) reageert op inoculatie met isolaten van de schimmel (twee aardappel- en twee essenisolaten)
Verticillium wilt of Fraxinus excelsior
Hiemstra, J.A. - \ 1995
Agricultural University. Promotor(en): R.A.A. Oldeman; J. Dekker. - S.l. : Hiemstra - ISBN 9789054853602 - 213
verticillium - bosbouw - plantenziekteverwekkende schimmels - plantenziekteverwekkende bacteriën - bomen - antagonisme - verwelkingsziekten - moniliaceae - wilts - forestry - plant pathogenic fungi - plant pathogenic bacteria - trees - antagonism
<p>Research on ash wilt disease, a common disease of <em>Fraxinus excelsior</em> L. <em></em> in young forest and landscape plantings in several parts of the Netherlands, is described. By means of a survey for pathogenic fungi in affected trees, inoculation and reisolation experiments it is demonstrated that the disease is caused by <em>Verticillium dahliae</em> Kleb. Host specificity and virulence of a <em>V.</em><em>dahliae</em> isolate from ash are compared to those of isolates from elm, maple and potato. Disease incidence and progress, and recovery of infected trees are investigated through monitoring experiments in two permanent plots in seriously affected forest stands. Monitoring results are related to the results of an aerial survey for ash wilt disease in the province of Flevoland to assess the impact of the disease on ash forests. Furthermore, pathological xylem anatomy of infected ash trees is described and mechanisms of recovery are discussed. Finally, results are integrated and related to data on ash and on verticillium. wilts of other tree species presented in literature reviews in the starting chapters of the book.
De bacterie-verwelkingsziekte in dahlia's
Kamerman, W. ; Saaltink, G.J. - \ 1968
Lisse : Laboratorium voor Bloembollenonderzoek (Praktijkmededeling / Laboratorium voor bloembollenonderzoek Lisse nr. 28) - 10
erwinia - verwelkingsziekten - dahlia - plantenziektebestrijding - bloembollen - teelt - onderzoeksinstituten - nederland - wilts - plant disease control - ornamental bulbs - cultivation - research institutes - netherlands
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