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Weed Hosts of Root-Knot Nematodes and Their Distribution in Fiji

  • Sunil K. Singh (a1), Uma R. Khurma (a1) and Peter J. Lockhart (a2)


Weeds can act as reservoir hosts of a range of pests and diseases. Information and knowledge on the host status of weeds to common pests and diseases can be used to develop integrated weed and pest management strategies. As part of a survey on the distribution and diversity of root-knot nematodes on crops in Fiji, the root-knot nematode host status of weeds was also studied. Weeds growing in root-knot nematode infested farms (n = 189) and bioassay pot soil samples (n = 277) were identified, and their host status was determined on the basis of a root gall and egg-mass index scale from 0 to 5. A total of 45 weed species were recorded as potential weed hosts of root-knot nematodes with a gall index from 1 to 5. Using the weed and tomato bioassay method, a total of 11 nonhost weed species were recorded with a gall index of 0, relative to infected tomato growing in pot soil samples. Common weeds infected by root-knot nematodes on farms and in bioassay pot soil included slender amaranth, old world diamond-flower, tropic ageratum, sicklepod, mimbra, balsamapple, purple bushbean, little ironweed, ivy gourd, and cutleaf groundcherry. The presence of egg masses on the weed hosts indicated their ability to sustain root-knot nematode populations and, thus, their potential to act as reservoir hosts.

Las malezas pueden actuar como hospederas de una amplia variedad de plagas y enfermedades. La información y los conocimientos acerca de la manera en que las malezas pueden ser hospederas de las plagas y enfermedades comunes pueden utilizarse para desarrollar estrategias integradas del manejo de éstas mismas. Como parte de una encuesta acerca de la distribución y diversidad de los nemátodos del género Meloidogyne en cultivos producidos en Fiji, también se estudio el grado en que las malezas funcionan como hospederas de dichos organismos. Se identificaron malezas que crecen en granjas infestadas con Meloidogyne (n = 189) y en muestras de ensayo de tierra de macetas (n = 277) y su estatus de hospederas fue determinado en base a los nódulos radiculares y a la masa de huevecillos presente en una escala de 0 a 5. Un total de 45 especies de maleza fueron identificadas como hospederas potenciales de Meloidogynes con un índice de nódulos radiculares de 1 a 5, usando el método de bio-ensayo en malezas y tomate, un total de 11 especies de malezas no hospederas se registraron con un índice de nódulos de 0, en relación al tomate infectado que crecía en las muestras de tierra de macetas. Las malezas comunes infectadas con Meloidogynes en granjas y en muestras de suelo de macetas, incluyeron Amaranthus viridus L., Oldenlandia corymbosa L.; Ageratum conyzoides L.; Senna obtusifolia (L.) H.S. Irwin & Barneby; Ludwigia hyssopifolia (G.Don) Excell apud A. R. Fernandes; Momordica charantia L.; Macroptilium atropurpureum (Moc. & Sesse ex DC.) Urb.; Cyanthillium cinereum (L.) H. Rob.; Coccinia grandis (L.) J. Voigt y Physalis angulata L. La presencia de masas de huevecillos en las malezas hospedaras indica su habilidad para mantener poblaciones de Meloidogynes y por lo tanto, su potencial para actuar como hospederas.


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