Plant-parasitic nematodes: how do we manage them?

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    PLANT-PARASITIC NEMATODES: HOW DO WE MANAGE THEM?
    Nicole Viaene
    Institute for Agricultural and Fisheries Research, Merelbeke; Faculty of Sciences, UG, Ghent University,
    nicole.viaene@ilvo.vlaanderen.be

    Plant-parasitic nematodes are a small fraction of the phylum Nematoda, but they have a huge impact
    on man by reducing yields of agricultural crops. These microscopic round worms damage plants by
    feeding on the plant cell content, by migrating through tissues, and providing entrance for
    pathogenic fungi and bacteria into the already weakened plant.
    As most symptoms of infection by plant-parasitic nematodes e.g. reduced plant vigour, are not
    specific, these organisms are often not recognized as causal agents of crop loss. A first step in
    managing plant-parasitic nematodes is adequate detection. This requires appropriate sampling,
    extraction and identification techniques. The latter are changing rapidly from morphology-based
    identification by specialists using microscopes, to molecular (DNA)-based methods which do not
    require such specific training. By making detection methods more accessible and cheaper, diagnostic
    laboratories are able to analyze more samples. Plant-parasitic nematodes, the “hidden enemy”, will
    become more visible this way, so that the real management can start.

    When plant-parasitic nematodes in seeds, wood, flower bulbs or roots are killed by destroying the
    (imported) commodity, or by heat-treatment or fumigation; the term control sensu stricto is used.
    However, when dealing with nematodes in farmer fields, even the most toxic nematicide is not able
    to kill all plant-parasitic nematodes. Moreover, as most nematicides have been banned (at least in
    Europe) in the last two decades, an integrated management approach is the only option. This means
    keeping population levels of plant-parasitic nematodes below an appropriate damage threshold so
    that crop production is possible without economic loss.
    Several “old” cultural practices have gained interest again, such as crop rotation, but now using
    resistant cultivars or green manures. New variations on old themes are solarisation, inundation and
    anaerobic soil disinfestation, but also adding organic matter to soil. Organic amendments give rise to
    a larger diversity of soil micro- organisms, including antagonists, and make the soil suppressive
    and/or or the plant less vulnerable. Currently, many studies are trying to unravel the complexity of
    these mechanisms so that we can understand the processes between soil, plant and nematode. With
    the answers we hope to steer the process in the right direction: reducing densities of plant-parasitic
    nematodes in the field. This could be done by manipulating the soil environment (e.g. adding
    compost, biocontrol organisms, …) or manipulating the plant (e.g. changing genes). The step from lab
    and greenhouse trial towards the field environment is the most difficult one, but still needs to be
    taken for many of the mechanisms discovered so far.
    Last, but really first, is of avoidance or prevention: keeping plant-parasitic nematodes out of the field,
    out of a country or a region. International as well as national regulations, including quarantine status,
    are very important tools here and even though only a small fraction of harmful nematodes are
    detected this way, having rules in place reduces spread. Ways of spread, together with survival and
    basic nematode biology have been neglected topics in this era of molecular research. They are,
    however, the corner stones of an integrated nematode management.
    Oorspronkelijke taalEngels
    TitelAnnual Scientific Meeting of the Belgian Society of Parasitology and Protistology
    Aantal pagina’s1
    Publicatiedatum13-nov-2014
    PublicatiestatusGepubliceerd - 13-nov-2014
    EvenementAnnual Scientific Meeting of the BSPP - Antwerpen, België
    Duur: 13-nov-201413-nov-2014
    http://www.bspp.be

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