Vertical and horizontal distribution of and soil sampling for root lesion nematodes (Pratylenchus neglectus and R thornei) in South Australia

Vertical and horizontal distribution of and best sampling techniques for Pratylenchus neglectus and P thornei were studied in several different soil types in South Australia. Nematodes were recovered to depths of 60 cm in shallower soils and up to 90 cm in deeper clays. Between 47% and 84% of the population of Pratylenchus spp. was recovered from the top 0–10 cm, and 64–94% of the population from the top 20 cm. Higher proportions of Pratylenchus were found in the top 10 cm of sands and sandy loams than clay soil types. More Pratylenchus spp. were recovered within plant rows of the previous erop than between rows at only one of the five sites assessed. In dry soil, recovery of Pratylenchus spp. was higher using an undisturbed soil core with water added than in samples collected with an auger, In wet soil, both techniques gave similar results. Based on this information, to obtain maximum recovery of nematodes it is recommended to add water to dry soil before sampling for Pratylenchus spp.