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.

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Ontwikkelingen in bestrijding Verticillium dahliae in de Boomkwekerij
Sluis, Bart van der - \ 2013
verticillium dahliae - fungal diseases - street trees - cultural control - pratylenchus - propagation materials - rootstocks - biological soil sterilization - varietal resistance
Wortellesieaaltjes in lelie beheersen met behulp van NemaDecide
Elberse, I.A.M. - \ 2012
nematoda - bloembollen - beslissingsondersteunende systemen - rotaties - pratylenchus - lelies - akkerbouw - ornamental bulbs - decision support systems - rotations - lilies - arable farming
Poster met informatie over NemaDecide en de mogelijkheden van dit systeem voor de bloembollenteelt.
Aaltjesmanagement in de akkerbouw - achtergronden
Aasman, B. ; Beers, T.G. van; Wolfs, A. - \ 2010
Kennisakker.nl 2010 (2010)9 juni.
gewasbescherming - plagenbestrijding - nematoda - plantenparasitaire nematoden - meloidogyne - pratylenchus - ditylenchus - nematodenbestrijding - akkerbouw - plant protection - pest control - plant parasitic nematodes - nematode control - arable farming
Informatie over plantparasitaire aaltjes ( cysteaaltjes, wortelknobbelaaltjes, wortellesieaaltjes, vrijlevende wortelaaltjes en stengelaaltje).
Duurzaam telen verhoogt bodemweerbaarheid : GoeddoorGrond
Os, G.J. van; Bent, J. van der - \ 2010
duurzaamheid (sustainability) - bodemfauna - organische stof - compost - pythium - rhizoctonia - pratylenchus - duurzaam bodemgebruik - bodemweerbaarheid - sustainability - soil fauna - organic matter - composts - sustainable land use - soil suppressiveness
Bacteriën en schimmels in de grond kunnen ziekten en plagen onderdrukken, de zogenaamde bodemweerbaarheid. Deze poster gaat over het effect van duurzaam telen op de bodemweerbaarheid.
Effectieve gewasbescherming in substraatbedden
Wurff, A.W.G. van der; Messelink, G.J. ; Wensveen, W. van; Vermeulen, P.C.M. ; Slooten, M.A. van; Groot, E.B. de; Labrie, C.W. ; Raaphorst, M.G.M. ; Vermeulen, T. ; Blok, C. - \ 2010
cultuur zonder grond - chrysanten - chrysanthemum - gewasbescherming - pythium - verticillium - meloidogyne - pratylenchus - frankliniella occidentalis - glastuinbouw - soilless culture - chrysanthemums - plant protection - greenhouse horticulture
Poster met informatie over onderzoek naar een ziekteweerbaar substraatbedden systeem voor het modelgewas chrysant tegen de bodemgebonden ziekten en plagen Pythium, Verticillium, Meloidogyne (wortelknobbelaaltje), Pratylenchus (wortellesie aaltje) en Frankliniella occidentalis (trips).
Geïntegreerde gewasbescherming rozenteelt
Kuik, A.J. van - \ 2009
snijbloemen - rozen - nematoda - verticillium - pratylenchus - vollegrondsteelt - bodemweerbaarheid - cut flowers - roses - outdoor cropping - soil suppressiveness
Poster met informatie uit onderzoek naar beheersing van onkruiden en schimmels in de rozenteelt
Aaltjes in vaste planten en zomerbloemen : hygiëne, uitgangsmateriaal en vruchtwisseling vormen de basis
Helm, F.P.M. van der; Wurff, A.W.G. van der; Zuilichem, J.A.A. van; Duyvesteijn, R.G.E. ; Elberse, I.A.M. ; Hoffmann, M. ; Geers, F.A.M. - \ 2009
[S.l.] : Praktijkonderzoek Plant & Omgeving B.V.
nematoda - meloidogyne - pratylenchus - ditylenchus dipsaci - aphelenchoides fragariae - aphelenchoides ritzemabosi - paratylenchus bukowinensis - trichodoridae - overblijvende planten - bloementeelt - inundatie - gewasbescherming - vollegrondsteelt - biofumigatie - zomerbloemen - perennials - floriculture - flooding - plant protection - outdoor cropping - biofumigation - summer flowers
Hoewel aaltjes in de land- en tuinbouw een slechte reputatie hebben, is het merendeel van de aaltjes niet schadelijk voor de gewassen. Sterker nog, de meerderheid speelt een belangrijke rol in de mineralen- en nutriëntenhuishouding van de bodem. Dit zijn met name de bacterie- en schimmeletende aaltjes. Slechts een kleine groep is verantwoordelijk voor schade aan zomerbloemen en vaste planten. Algemene schadebeelden zijn groeiachterstand, slechte bloemproductie en slechte vermeerdering. Daarnaast vormen knobbels op en beschadigingen (lesies) van de wortel een probleem bij de export van planten.
Samenvatting Monitoring Nulsituatie-Rapport Resultaten meetronde 2005-2006
Keidel, H. ; Beers, T.G. van; Doornbos, J. ; Molendijk, L.P.G. - \ 2008
Gewasbescherming 39 (2008)1. - ISSN 0166-6495 - p. 19 - 21.
akkerbouw - grondanalyse - nematoda - nematodenbestrijding - heterodera schachtii - globodera - meloidogyne - pratylenchus - rotylenchus - tylenchorhynchus - longidorus - soorten - bedrijfsvoering - vragenlijsten - gewasbescherming - arable farming - soil analysis - nematode control - species - management - questionnaires - plant protection
Eind 2004 is door het Hoofdproductschap Akkerbouw (HPA), het Productschap Tuinbouw (PT) en LTO Nederland het initiatief genomen om de aaltjesproblemen gezamenlijk aan te pakken. Hiervoor is het actieplan aaltjesbeheersing gelanceerd. Eén van de projecten binnen dit actieplan was het monitoren van de nulsituatie. Dit project is uitgevoerd door een consortium van Blgg BV, NAK AGRO BV, en PPO-AGV. Binnen het project zijn tussen 2005 en 2006 425 akkerbouwbedrijven grondmonsters genomen. Deze zijn geanalyseerd op de meest bekende plantenparasitaire aaltjes. Daarnaast is aan de deelnemers gevraagd mee te werken aan een enquête over hun bedrijfsvoering en hun ervaringen met aaltjes
Factoren die de schadelijkheid van Pratylenchus bepalen
Kok, C.J. ; Zoon, Frans ; Hok-A-Hin, C.H. ; Poleij, L.M. - \ 2008
pratylenchus - pratylenchus penetrans - aardappelen - verticillium dahliae - plantenparasitaire nematoden - potatoes - plant parasitic nematodes
De schadelijkheid van Pratylenchus wordt sterk beïnvloed door omgevingsfactoren, zoals bodemtype en aanwezigheid van andere pathogenen. Verder zou ook de afbraaksnelheid van besmet wortelmateriaal in de bodem een rol kunnen spelen in de populatieontwikkeling
Projectervaringscijfers Limburg (PECAL)
Runia, W.T. ; Molendijk, L.P.G. ; Rouwette, F. - \ 2008
Gewasbescherming 39 (2008)1. - ISSN 0166-6495 - p. 23 - 23.
akkerbouw - groenteteelt - nematoda - gewasverliezen - gewasopbrengst - grondanalyse - bemonsteren - aardappelen - rotatie - meloidogyne - pratylenchus - trichodoridae - gewasbescherming - vollegrondsgroenten - vollegrondsteelt - arable farming - vegetable growing - crop losses - crop yield - soil analysis - sampling - potatoes - rotation - plant protection - field vegetables - outdoor cropping
In zuidoost Nederland vormen aaltjes een probleem in de akkerbouw en vollegrondsgroenteteelt op zandgrond. Op zestien bedrijven met zandgrond is informatie verzameld over aaltjes en aaltjesschade. Voorop stond het in kaart brengen van de doelmatigheid van de aaltjesbeheersingsstrategie op de besmette bedrijven en waar mogelijk suggesties te doen voor verbetering. In totaal zijn 183 grondanalyses verkregen van 79 percelen van deze bedrijven. M. chitwoodi, soms in combinatie met M. fallax, is het meest voorkomende aaltje, daarnaast komen trichodoriden en P. penetrans veelvuldig voor
Alternatieve aaltjesonderdrukkende gewassen : eindrapportage
Elberse, I.A.M. ; Visser, J.H.M. ; Verstegen, H.A.G. - \ 2007
Lisse : PPO Bloembollen en Bomen - 23
pratylenchus - waardplanten - plantenziektebestrijding - bloembollen - groenbemesters - helenium - gaillardia - parelgierst - sorghum sudanense - biologische bestrijding - host plants - plant disease control - ornamental bulbs - green manures - pearl millet - biological control
In een deskstudie in 2004 bleken vier gewassen perspectief te bieden als aaltjesonderdrukkend gewas: Helenium, Gaillardia, parelgierst (speciale Canadese cultivar) en soedangras. Na overleg met de sector zijn de drie gewassen, Helenium, parelgierst en soedangras, in een veldproef in 2005 getest op hun onderdrukkende werking van wortellesieaaltjes (Pratylenchus- soorten). Tevens werd het nieuwe ras T. patula ‘Evergreen’ (K. Sahin, Zaden B.V.) in deze proef meegenomen. Omdat wortellesieaaltjes zich goed kunnen vermeerderen op veel onkruiden is de mate van onkruidgroei in de gewassen ook beoordeeld. Verder werd geprobeerd om inzicht te krijgen in de kosten van de teelt van deze gewassen. In 2006 zijn Helenium, parelgierst en soedangras in een veldproef getest op hun werking tegen het noordelijk wortelknobbelaaltje (Meloidogyne hapla). Het nieuwe Tagetesras werkte even goed als de bestaande Tagetesrassen qua wortellesieaaltjesonderdrukking en onkruidonderdrukking. Over de werking van Helenium tegen wortellesieaaltjes kunnen geen conclusies worden getrokken, wegens de slechte kieming van dit gewas. Bij navraag in de praktijk bleek het ook daar moeilijk om Helenium vanuit zaad op een akkerbouwmatige manier te telen. In de proef van 2006 werd Helenium aangeplant in plaats van gezaaid. De teelt ging goed. Het aantal M. hapla liep terug tot bijna nul, maar omdat bij de vatbare referent ook een afname van M. hapla optrad, kan geen conclusie over de werking worden getrokken. Voor een teelt van Helenium als groenbemester zijn de kosten nogal hoog. Het zaad is erg duur en bovendien zijn er problemen met de kieming. Parelgierst zorgde wel voor een verlaging van de wortellesieaaltjespopulatie, maar werkte minder goed dan verwacht volgens de literatuur. De werking was even goed als braak en dus niet goed genoeg. Omdat de vatbare referent niet naar behoren werkte, kunnen er geen conclusies worden getrokken over de werking van parelgierst tegen M. hapla. Hoewel soedangras na onderwerken blauwzuurgas produceert, waaraan aaltjes dood gaan, is het risico van wortellesieaaltjesvermeerdering tijdens de teelt te groot om dit op een perceel met wortellesieaaltjes te telen. Ook over de werking van soedangras tegen M. hapla kunnen geen conclusies worden getrokken. Een teelt van soedangras is goedkoper dan een afrikaantjesteelt. In 2006 kwam een nieuw gewas naar voren, dat wortellesieaaltjes zou onderdrukken: Japanse haver (Avenastrigosa). Dit gewas is nog in onderzoek. Om de aaltjesonderdrukking goed te kunnen meten, is in deze proeven op normale wijze het onkruid bestreden. Net voorafgaand aan de onkruidbestrijding is de mate van onkruidgroei in alle veldjes gescoord. Bij parelgierst en soedangras stond er in het begin van het seizoen meer onkruid dan bij de andere gewassen en braak. Later groeiden juist deze twee gewassen heel snel dicht. In het algemeen stond er weinig onkruid en, behalve in het slecht gekiemde Helenium, vormde onkruid in geen enkel gewas een probleem. Om de onkruidonderdrukkende werking beter te kunnen bekijken, dient een proef te worden gedaan waarin onkruid niet wordt bestreden. Dit gaat niet samen met de proef naar aaltjesonderdrukkende werking.
Combibemonstering
Zijlstra, C. ; Been, T.H. - \ 2007
plantenparasitaire nematoden - nematoda - meloidogyne - pratylenchus - bemonsteren - technieken - plant parasitic nematodes - sampling - techniques
Onderzoek naar een betrouwbare combibemonsteringsmethode die meerdere aaltjessoorten nauwkeurig kan vaststellen
Groenbemesters en Pratylenchus in een bouwplan met zetmeelaardappelen
Brommer, E. - \ 2006
Kennisakker.nl 2006 (2006)15 sept.
groenbemesters - aardappelen - pratylenchus crenatus - pratylenchus - waardplanten - nematoda - nematodenbestrijding - fabrieksaardappelen - akkerbouw - rotaties - green manures - potatoes - host plants - nematode control - starch potatoes - arable farming - rotations
Het wortellesie-aaltje P. penetrans vermeerdert op veel gewassen, waaronder aardappel en graan. Suikerbiet is een slechte waard voor dit aaltje. De meeste groenbemesters zijn ook een goede waard. In opdracht van HPA is onderzoek verricht naar de effecten van groenbemesters op het aaltje en de opbrengst van de aardappels het volgende teeltjaar. De vraag is welke groenbemester het best geteeld kan worden na granen, als voorvrucht van zetmeelaardappelen. Het gaat dan om de aaltjesvermeerdering, maar ook om het positieve effect van groenbemesters op de structuur en organische stof, en daardoor op de aardappelopbrengst. Tevens is onderzocht welk graangewas, wintertarwe of zomergerst het aaltje het minst vermeerdert. Zomergerst is een betere voorvrucht voor aardappel dan wintertarwe, doordat de aaltjespopulatie na gerst lager is. Tijdens zwarte braak daalt de populatie P. penetrans, dit heeft een positief effect op de aardappelopbrengst. Dit is een samenvatting van het rapport "Groenbemesters en Pratylenchus in een bouwplan met zetmeelaardappelen. Resultaten van drie jaar onderzoek", er is een link naar dit rapport aanwezig.
Aaltjes vooral via preventie aanpakken
Rovers, J.A.J.M. - \ 2005
Groenten en Fruit. Algemeen (2005)21. - ISSN 0925-9694 - p. 30 - 31.
gewasbescherming - plagenbestrijding - nematoda - preventie - controle - bestrijdingsmethoden - bemonsteren - methodologie - monitoring - grondanalyse - meloidogyne chitwoodi - pratylenchus - tagetes - brassica - knolselderij - groenbemesters - nematodenbestrijding - vollegrondsteelt - plant protection - pest control - prevention - control - control methods - sampling - methodology - soil analysis - celeriac - green manures - nematode control - outdoor cropping
In een gezonde bodem kunnen in een kilo grond tot 40 duizend aaltjes zitten. De meeste daarvan zijn nuttig, omdat ze allerlei schadelijke bacteriën, schimmels en insecten opruimen. Helaas zitten er ook schadelijke aaltjes tussen. Preventieve maatregelen hiertegen kunnen veel leed voorkomen. Op de site van kennisakker is onder de knop 'advies' het programma digi-aal te vinden, met informatie over de gevoeligheid van gewassen en de mate van vermeerdering van aaltjes, ondersteund met afbeeldingen van symptomen
Het testen van opgeschaalde Seinhorst-opspoelkannen
Bekkum, P.J. van; Beers, T.G. van; Beniers, J.E. - \ 2000
Gewasbescherming 31 (2000)3. - ISSN 0166-6495 - p. 65 - 67.
aardappelen - dieren - populatiedichtheid - populatie-ecologie - mortaliteit - populatiegroei - ziekteresistentie - plaagresistentie - fysica - meting - methodologie - ? - globodera - potatoes - pratylenchus - heteroderidae - tylenchidae - animals - population density - population ecology - mortality - population growth - disease resistance - pest resistance - physics
Om een voldoende grote statistische betrouwbaarheid voor de bepaling van populatiedichtheden van Globodera spp. in wetenschappelijke experimenten of bij het testen van aardappelcultivars ten behoeve van hun partiele resistentie-eigenschappen te verkrijgen, is het nodig om zowel de begin- als de einddichtheid van het aaltje nauwkeurig te bepalen. Twee methoden voor de bepaling van de relative vatbaarheid van aardappelrassen voor aardappelcysteaaltjes worden vergeleken
Grote verschillen : waardplantgeschiktheid van akkerbouwgewassen, grove groenten en groenbemestingsgewassen voor Meloidogyne fallax en meloidogyne chitwoodi
Molendijk, L.P.G. ; Nijboer, H. - \ 1998
PAV-bulletin. Vollegrondsgroenteteelt / Praktijkonderzoek voor de Akkerbouw en de Vollegrondsgroenteteelt 1998 (1998)1. - ISSN 1385-5298 - p. 24 - 25.
gastheerreeks - plantenziekten - plantenplagen - bodem - nematoda - pratylenchus - heteroderidae - tylenchidae - groenbemesters - host range - plant diseases - plant pests - soil - green manures
Potato crop growth as influenced by potato cyst nematodes (Globodera pallida) and abiotic factors
Ruijter, F. de - \ 1998
Agricultural University. Promotor(en): G.R. Findenegg; A.J. Haverkort. - S.l. : De Ruijter - ISBN 9789054858195 - 121 p.
solanum tuberosum - aardappelen - plantenplagen - pratylenchus - heteroderidae - tylenchidae - bodem - nematoda - potatoes - plant pests - soil
<p>The objective of the research described in this thesis was to determine the major mechanisms by which potato cyst nematodes reduce potato crop growth and to explain interactions known to occur with cultivar and abiotic factors. Understanding of these interactions may lead to strategies that potato growers can use to minimise nematode damage.</p><p>The research concentrated on the interaction between nematodes and soil-related factors. Experiments were carried out, mainly under field conditions, in which the effects of varying levels of nematode density, soil compaction, soil pH and phosphorus fertilisation on crop growth of potato cultivars were studied over time. Two methods for studying root growth in the field were compared and special attention was paid to the effects of nematodes on root growth.</p><p>It was found that potato cyst nematodes reduced crop growth at early stages of growth by inducing or aggravating phosphorus deficiency. Compensatory root growth alleviated phosphorus deficiency at later stages of growth. Application of phosphorus fertiliser reduced or prevented nematode-induced phosphorus deficiency, but could not fully prevent nematode damage. Obviously, penetration of nematodes in the roots also impaired crop photosynthesis also through mechanisms other than nutrient deficiency.</p><p>At late stages of growth, nematodes accelerated crop senescence. This was associated with reduced concentrations of nutrients in the foliage, though it seems likely that more mechanisms could be responsible. To resolve this, further study of the senescence of infested crops and options for remedying this is required.</p><p>It was found that tolerance of cultivars to potato cyst nematodes is associated with production of extra roots and large tops, a characteristic of late maturing potato cultivars. The influence of soil parameters on nematode damage was also found to depend on the amount of foliage produced. It is inferred that crops with large tops suffer little yield loss as they are able to maintain ground cover and light interception, even after infestation by potato cyst nematodes.</p><p>It is concluded that farmers can minimise yield loss by choosing tolerant cultivars and by cultural measures. It is suggested that initial nematode-induced phosphorus deficiency can be relieved by fertilisation methods that increase phosphorus in infested plants to adequate levels. Crop senescence may be delayed by increasing nitrogen in infested plants, e.g. by foliar application of a nitrogen fertiliser, but this requires further study.</p>
Genetic diversity of the potato cyst nematode in the Netherlands
Folkertsma, R.T. - \ 1997
Agricultural University. Promotor(en): R.W. Goldbach; F.J. Gommers; Jaap Bakker. - S.l. : Folkertsma - ISBN 9789054857488 - 88 p.
plantenplagen - pratylenchus - heteroderidae - tylenchidae - solanum tuberosum - aardappelen - genetische variatie - overerving - rassen (dieren) - rassen (taxonomisch) - moleculaire genetica - plantenveredeling - ziekteresistentie - plaagresistentie - globodera pallida - globodera rostochiensis - plant pests - potatoes - genetic variation - inheritance - breeds - races - molecular genetics - plant breeding - disease resistance - pest resistance
<br/>The potato cyst nematodes <em>Globodera rostochiensis</em> (Woll.) <em></em> Skarbilovich and <em>G. pallida</em> (Stone) originate from the Andes region in South America and have been introduced into Western Europe since 1850. Both species are successful colonizers. Once primary founders have established vital populations, an area is rapidly colonized by secondary founding events. The mode of spread results in patchy distribution patterns. Analyses of the processes that influence the spatial variations in virulence are of major importance for the control by means of host plant resistance. The ability to unravel the mosaic distribution patterns of the two species and their pathotypes enables breeders and growers to anticipate on the dynamics of virulent populations. The aim of this thesis was to analyse the intra- and interspecific variation of <em>G. rostochiensis</em> and <em>G. pallida</em> in the Netherlands and to obtain insight in the processes that determine the spatial variations in protein, DNA and (a)virulence polymorphisms.<p><strong>interspecific variation</strong><p>The molecular variation between the sibling species <em>G.</em><em>rostochiensis</em> and <em>G.</em><em>pallida is</em> remarkably large. The RAPD technique revealed a total of 250 DNA fragments, of which only nine DNA fragments were common to both species (Chapter 3). Similar results were obtained with the AFLP assay. A total of 1000 AFLP fragments was amplified, of which only 64 fragments could be identified in both species (Chapter 4). These results agreed with previous investigations using 2-DGE and show that morphologically nearly indistinguishable organisms can be quite distinct the molecular level.<p>The extensive genetic differentiation of <em>G.</em><em>rostochiensis</em> and <em>G</em> . <em>pallida</em> offers perspectives for the development of a diagnostic assay. In addition the PCR technique enables the amplification of species specific fragments from small numbers of cysts extracted from soil samples. For example, <em>G. rostochiensis</em> specific DNA fragments can be amplified from single juveniles (Chapter 1).<p><strong>intraspecific variation</strong><p>The intraspecific variation of <em>G.</em><em>rostochiensis</em> as revealed by RAPDs and AFLPs is relatively low (Chapter 3 and 4). The proportion of polymorphic DNA fragments among nine <em>G. rostochiensis</em> populations was 19% and 15.8%, respectively. Three clusters of populations were identified and each cluster could be described by one or more specific DNA fragments.<p>The intraspecific variation of <em>G.</em><em>pallida,</em> as revealed with RAPDs or AFLPs, is larger in comparison with <em>G.</em><em>rostochiensis</em> (Chapter 3 and 4). The proportion of polymorphic RAPD fragments among 17 populations was 46%. For the AFLP assay this figure was 23% polymorphic AFLP fragments among 15 populations. The majority of the populations displayed a continuous range of variations. Only a few clearly diverged clusters could be discriminated on the basis of specific DNA fragments.<p>Various groups have applied the RAPD technique to study the genetic divergence among conspecific populations of plant parasitic nematodes. The validity of this technique was evaluated in chapter 4 by comparison of the clustering of 36 <em>G.</em><em>pallida</em> populations based on RAPD and 2-DGE data. Both data sets demonstrated that the majority of the <em>G.</em><em>pallida</em> populations were not clearly differentiated from each other. The overall correlation between the distance matrices derived from both data sets was low. Careful examination of the separate dendrograms showed similarity in clustering only for clearly diverged populations or groups of populations.<p>Although the AFLP and RAPD technique are simple, fast and require only minute amounts of biological material, they are not suitable to resolve the subtle differences among potato cyst nematode populations. Quantitative variation in allele frequencies is often not resolved with those techniques, which is, among others, due to the virtual inability to recognize co-dominant alleles and the non-linear amplification of DNA fragments. In chapter 6 and 7 the genetic variation was studied by analysing pools of individuals with 2-DGE. The ratios between the protein quantities produced by the codominant alleles are appropriate measures for the allele frequencies. The correctness of this method has been confirmed by 2-DGE of single individuals (De Boer <em>et</em><em>al</em> ., <em></em> 1992)<p><strong>bottleneck effects on the secondary founders</strong><p>The intraspecific variation among potato cyst nematode populations in Europe is predominantly determined by the genetic constitution of the primary founders, directly or indirectly introduced from South America, and the effect of random genetic drift on the secondary founders. To obtain insight in these processes, 226 <em>G.</em><em>pallida</em> populations from the Netherlands were analyzed with 2- DGE. The results strongly suggest that these populations originate from one source, or in case of multiple introductions, from a number of sources with a similar genetic makeup.<p>The genetic differentiation of the 226 <em>G.</em><em>pallida</em> populations indicate that the colonization of the Netherlands has been accompanied by extensive random genetic drift. Only a limited proportion of the populations appeared to be identical. It is also shown, that the bottleneck effects differ between regions. Significant variation in population structure was observed between the three investigated areas. The genetic variation within <em>G.</em><em>pallida</em> populations from north Friesland and the IJsselmeerpolders is in general smaller than within populations from the northeast Netherlands. A plausible explanation for this phenomena is the low multiplication rate of potato cyst nematodes due to wider crop rotation schemes in the IJsselmeerpolders and north Friesland. These factors result in a slow expansion of newly founded populations, which enhances the effect of drift.<p><strong>gene-pool similarity concept</strong><p>The gene-pool similarity concept rests on the hypothesis that in the absence of selection pressure by host plant resistance, degrees of similarity between populations revealed by molecular techniques are also reflected at virulence loci, including those not yet resolved. To test this concept, the genetic variation revealed by 2-DGE among 102 <em>G.</em><em>pallida</em> populations was compared with the variation in virulence towards two resistant cultivars. This analysis showed that a decrease in genetic distance among populations is accompanied with a decrease in variation in virulence. In addition it is demonstrated that the gene pool similarity concept is also applicable to loci determining the variation in fitness among populations. The variation in Pf/Pi values among the 102 populations on Désirée is in general smaller between closely related populations than between distantly related populations.<p><strong>breeding for resistance</strong><p>Breeding for resistance has been dominated by trial-and-error approaches, which has stimulated the view that control by means of host plant resistance is unavoidably a short-term approach due to the 'appearance' of virulent populations. The pervasive myth that breeding for resistance against potato cyst nematodes is a lost arms race is challenged by the results of this thesis. Until recently it was assumed that the genetic variation of <em>G.</em><em>pallida</em> in the Netherlands was too large to produce potato cultivars with broad-spectrum resistance. In this thesis it is shown that the genetic diversity introduced from the Andes region has been limited and that the variation among the Dutch <em>G.</em><em>pallida</em> populations is mainly the result of random genetic drift. The elaborate analysis of 226 Dutch <em>G.</em><em>pallida</em> populations offers perspectives to obtain potato cultivars with broad and durable resistance. The gene pool similarities revealed by 2-DGE can be used as guidance in testing the effectiveness of new sources of resistance.
Resistance to root-knot nematodes, Meloidogyne spp., in potato
Janssen, G.J.W. - \ 1997
Agricultural University. Promotor(en): Evert Jacobsen. - S.l. : Janssen - ISBN 9789054856764 - 111 p.
plantenveredeling - ziekteresistentie - plaagresistentie - solanum tuberosum - aardappelen - plantenplagen - pratylenchus - heteroderidae - tylenchidae - plant breeding - disease resistance - pest resistance - potatoes - plant pests
<p>Root-knot nematodes, <em>Meloidogyne</em> spp., are world-wide one of the most damaging pests to arable farming. In North Western Europe, the species M. <em>chitwoodi, M. fallax</em> and <em>M. hapla</em> are becoming a serious problem in potato growing areas as a result of recent changes in crop rotation, that now include highly profitable host crops, and a reduced use of nematicides in potato. The root-knot nematodes can cause yield reduction and deteriorate the quality of the tuber to an unmarketable product. Since root-knot nematodes can multiply inside the tuber, infected potato tubers are a threat to infest <em>Meloidogyne-free</em> fields. To prevent this way of dispersal, quarantine measures will be in force for seed tubers in the countries of the European Community from August 1997.<p>Plant resistance is an effective, economical and environmentally safe alternative to control root-knot nematodes, but resistance is lacking in the presently used potato cultivars. The goal of the research described in this thesis was to identify and evaluate sources of resistance to <em>M. chitwoodi, M. fallax</em> and <em>M. hapla</em> and, if present, to initiate the transfer of resistance into cultivated potato.<p>A large screening of wild <em>Solanum</em> spp. was performed to identify sources of resistance to <em>M. chitwoodi, M. fallax</em> and/or <em>M. hapla</em> by selecting seedlings, which showed no to hardly any reproduction of the nematodes on the roots. High levels of resistance to both <em>M. chitwoodi</em> and <em>M. fallax</em> were observed in genotypes of <em>S. bulbocastanum, S. cardiophyllum, S. brachistotrichum, S. fendleri</em> and <em>S. hougasii,</em> whereas additionally moderate resistance to <em>M. fallax</em> was present in S. <em>stoloniferum</em> and S. <em>chacoense</em> and to <em>M. chitwoodi</em> in S. <em>gourlayi.</em> More <em>Solanum</em> species were selected with resistance to M. <em>hapla,</em> namely S. <em>bulbocastanum, S. brachistotrichum, S. cardiophyllum, S. arnezii, S. chacoense, S. tarijense, S. boliviense, S. gourlayi, S. microdontum, S. sparsipilum, S spegazzinii, S. sucrense, S. acaule</em> and <em>S. hougasii.</em> In general, resistance to <em>M. chitwoodi</em> and M. <em>fallax</em> was restricted to <em>Solanum</em> species originating from Central America, whereas resistance to <em>M. hapla</em> was present in numerous Central- and South American <em>Solanum</em> species. This might indicate that co-evolution has occurred between <em>M. chitwoodi</em> and related <em>M. fallax</em> and Central American <em>Solanum</em> species.<p>The following step was the evaluation of resistance with regard to the effectivity and working spectrum. In a glasshouse, resistant and susceptible <em>Solanum</em> genotypes were tested with two to four populations of <em>M. chitwoodi, M. fallax</em> and <em>M. hapla</em> to determine the level of resistance and to detect the presence of virulent populations within these <em>Meloidogyne</em> species. Resistant genotypes of S. <em>bulbocastanum, S. hougasii, S. cardiophyllum</em> and S. <em>fendleri</em> showed an almost absolute level of resistance and were able to suppress all populations of M. <em>chitwoodi</em> and <em>M. fallax</em> tested. Some genotypes of S. <em>chacoense</em> and S. <em>stoloniferum</em> showed moderate resistance to M. <em>fallax,</em> but not or in a lesser extent to <em>M. chitwoodi.</em> In contrast, large differences in virulence were observed between the four tested populations of <em>M. hapla</em> on resistant genotypes of S. <em>bulbocastanum, S. hougasii, S. chacoense, S. gourlayi, S. sparsipilum</em> and S. <em>spegazzinii.</em> Some genotypes with resistance to <em>M. chitwoodi, M. fallax</em> andlor <em>M. hapla</em> were also tested against isolates of the tropical and subtropical <em>Meloidogyne</em> species <em>M. incognita, M. arenaria</em> and <em>M. javanica,</em> but resistance was not effective to these high temperature adapted species.<p>The effectivity of resistance of some selected wild <em>Solanum</em> species was also evaluated under natural field conditions. In two fields in the Netherlands, naturally infested with <em>M. hapla</em> or <em>M. fallax,</em> the level of infection of soil surrounding resistant and susceptible genotypes was followed during a growing season. From August onwards, large differences in number of second-stage juveniles were present between resistant and susceptible genotypes. At the end of the growing season, the level of infection in soil of resistant wild <em>Solanum</em> genotypes was equal or lower compared to the beginning, whereas soil surrounding susceptible wild and cultivated genotypes showed a 7- to 22-fold increase of nematode infection. The results were comparable with the resistance tests in glasshouse experiments.<p>An important feature for a rapid introgression of resistance is the inheritance and this has been investigated for the resistance to <em>M. chitwoodi</em> and <em>M. fallax</em> in <em>S.fendleri, S. hougasii</em> and S. <em>stoloniferum.</em> Although these <em>Solanum</em> species are polyploid, a disomic genetic behaviour can be expected as earlier indicated by cytogenetic and genetic studies. Various populations were produced from crosses between resistant and susceptible plants, self- pollinations and backcrosses within the wild <em>Solanum</em> species and segregation patterns of progenies in resistant and susceptible plants were analysed. The progeny tests of S. <em>fendleri</em> clearly indicated the action of a single dominantly inherited gene, effective against both <em>M. chitwoodi</em> and <em>M. fallax,</em> and the symbol R <sub>mc2</sub> is proposed for this gene. In the case of S. <em>hougasii,</em> difficulties were met in producing backcross populations, but results also indicated the presence of a simple dominant factor for both nematode species. From the results of progeny tests of S. <em>stoloniferum,</em> it was concluded that several additive genes are involved.<p>The introgression of resistance from various wild Central American <em>Solanum</em> species into the cultivated potato has been initiated through interspecific hybridisation. Crosses were made between diploid S. <em>tuberosum</em> and diploid S. <em>bulbocastanum, S. brachistotrichum and S. cardiophyllum,</em> but no plants were obtained from these crosses. From crosses of tetraploid S. <em>tuberosum</em> with tetraploid S. <em>stoloniferum</em> and <em>S. fendleri,</em> and of diploid S. <em>tuberosum</em> with hexaploid S. <em>hougasii</em> few seeds leading to tetraploid hybrids were obtained, sometimes after in vitro culture of immature seeds. The hybrid status was confirmed with RAPD markers and the ploidy level was analysed using flow cytometry. These cross combinations were thought not to be possible according to the Endosperm Balance Number hypothesis and the hybrids obtained are considered to be escapes. Backcrosses were made and a variable number of seeds leading to first backcrossed genotypes (BC <sub>1</sub> 's) was produced depending on the hybrid genotype. The introgression of resistance to root-knot nematodes from <em>S.fendleri, S. stoloniferum</em> and S. <em>hougasii</em> has now advanced to the evaluation of resistant BC <sub>1</sub> 's for other traits before continuation of further backcrosses.<p>In conclusion, resistance to the root-knot nematodes M. <em>chitwoodi, M. fallax</em> and <em>M. hapla</em> has been identified in various <em>Solanum</em> species and has the potential to become an effective tool to control these pathogens under field conditions after transfer into cultivated potato. The first steps of introgression of resistance into <em>S. tuberosum</em> has been made. The introduction of multiple sources of resistance in new potato cultivars will enable a resistance management based on durable exploitation of useful resistance genes from natural resources.
Aktiviteit van trichodoride aaltjes : een sleutel voor de beheersing van tabaksratelvirus : eindverslag van het projekt 'Overleving en aktiviteit van virusoverdragende nematoden (Trichodoridae) in de bloembollenteelt'
Zoon, F.C. ; Pavlickova, E. ; Heij, A. de - \ 1996
Wageningen : IPO-DLO (Urgentieprogramma bollenziekte- en veredelingsonderzoek ) - 20 p.
experimenten - heteroderidae - nederland - bloembollen - plantenziekten - plantenplagen - gewasbescherming - plantenvirussen - pratylenchus - onderzoek - tabaksratelvirus - tylenchidae - trichodoridae - experiments - netherlands - ornamental bulbs - plant diseases - plant pests - plant protection - plant viruses - research - Tobacco rattle virus
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