Root Lesion Nematodes

last update 24/9/06

Background/context: The root-lesion nematode, Pratylenchus spp., is the most widespread and best-known nematode pest of crops. The root damage caused by this nematode allows infection by root-rotting microorganisms, such as fusarium root and crown rot, and the resulting damage is often greater than that caused by the nematode alone. Root-lesion nematodes (Pratylenchus thornei and P. neglectus) are widely distributed in the northern grains region where their cost to wheat production is $45M/year ($33M loss from P. thornei and $12M from P. neglectus). The tolerance/intolerance reactions and the resistance/susceptibility reactions of wheat varieties are different for the two species of root-lesion nematodes. Thus accurate identification and quantification is needed in choosing varieties to sow in nematode-infested fields. Currently this is done by extraction of live nematodes and morphometric identification and enumeration under a compound microscope. Although a molecular method exists to quantify P. thornei in soil in South Australia this method is not directly applicable to the soils in the northern grain regions. This is due to different soils and difference in depth at which the nematode populations occur.

Aim: The Centre research focussed on determining where in the soil profile root lesion nematodes are most active and whether DNA based diagnosis could accurately detect and quantintify Pratylenchus thornei and P. neglectus in the deep reactive clay soils of the northern grain belt.

Major Outcomes: Molecular probes and techniques for extracting DNA from soil have been developed by CSIRO Division of Entomology and SARDI and applied for diagnosing root-lesion nematodes on farms in southern Australia by C-Qentec as part of the Predicta-B test. This research has shown that a single soil sample (as is sufficient in southern grain growing areas) is not sufficient to detect both pathogens and nematodes in the Northern grain growing regions. Future work in this area aims to further develop the method developed in this project to detect nematodes at the level of population characterisation.

For more information contact: Dr André Drenth Department of Primary Industries and Fisheries Phone: +61 (0)7 3896 9345 Email: Andre.Drenth@dpi.qld.gov.au