Survival of the root-lesion nematode Pratylenchus jordanensis Hashim in a fallow field after harvest of alfalfa

Abstract

Survival of Pratylenchus jordanensis Hashim was studied in a field in fallow after the harvest of a crop of alfalfa and in storage under laboratory conditions. The nematodes survived in dry roots/ root residues under field conditions for 100 days. Vertical migration of the nematodes to deeper soil layers was observed when the top soil layer dried up. High numbers of nematodes survived at both 0-15 and 16-30 cm depths for 100 days. Then the field was ploughed under, which caused the soil to dry and the populations to decline. The nematodes survived for 380 days in a fallow field. They survived for 270 and 272 days under laboratory conditions in wet and shade-dried soil, respectively, and for 124 days in natural field soil at 30 degrees C. Significant negative correlation between nematode populations and storage temperature and positive correlation between nematode populations and soil moisture were observed. P. jordanensis did not survive for long in a drop of water on a glass slide, whereas it survived in filter paper discs for varying periods at different relative humidity levels. Survie de Pratylenchus jordanensis Hashim dans les jacheres suivant la recolte de luzerne - La survie de Pratylenchus jordanensis Hashim dans les jacheres suivant la recolte de luzerne et dans du sol stocke au laboratoire a ete etudiee. Au champ, le nematode survit 100 jours dans les racines dessechees ou les fragments de celles-ci. Il a ete observe une migration verticale des nematodes vers les couches plus profondes du sol lorsque la surface de celui-ci se desseche. Un grand nombre de nematodes survivent 100 jours a des profondeurs de 0-15 et 16-30 cm apres quoi les populations declinent du fait de la dessiccation causee par le labourage du champ. A 30 degrees C, le nematode survit 270 jours dans du sol humide, 272 jours dans du sol seche a l'ombre - l'un et l'autre dans les conditions du laboratoire - et 124 jours dans le sol naturel au champ. Il a ete observe des correlations significatives, negatives, entre populations du nematode et temperature de stockage, et positives, entre populations du nematode et humidite du sol. P. jordanensis ne survit pars longtemps dans une goutte d'eau placee sur une lame porte-objet, tandis qu'il est capable de se maintenir pendant des periodes plus ou moins longues si place sur des disques de papier filtre soumis a des taux d'humidite relative varies.

Distribution and Longevity of Pratylenchus penetrans in the Red Raspberry Production System

“…Despite the large initial decrease, nematodes continued to be collected from root material in both fields after 8 mon, even though no evidence of any living roots was present from either treatment after 4 mon. Although active nematodes cannot survive without living roots, inactive individuals or eggs of P. penetrans may continue to survive in dead root material and soil (Mani, 1999). It is important to note that degradation of root fragments FIG.…”

Relationship Between Climatic Factors and Distribution of Pratylenchus spp. in the Dryland Wheat-Production Areas of Eastern Washington

“…Survival and reproduction of P. penetrans was largely reduced in very low or very high soil moisture (20). In addition, vertical movements of many species of Pratylenchus have been observed in response to moisture gradients (24,50). Fields with no detectable Pratylenchus spp.…”

Toward a holistic view of orchard ecosystem dynamics: A comprehensive review of the multiple factors governing development or suppression of apple replant disease

“…When topsoil dries up or conditions become adverse, Pratylenchus spp. have been shown to migrate to deeper layers of the soil profile, and eggs can survive even longer periods of desiccation (Mani, 1999). Some early studies suggested that P. penetrans populations are higher, and therefore cause more damage, in sandy and/or coarsetextured soils (Mai and Abawai, 1981); however, this has not been well documented.…”