Prevalence and diversity of plant parasitic nematodes in Northern Ireland grassland and cereals, and the influence of soils and rainfall

The prevalence and diversity of plant parasitic nematodes in Northern Ireland cereal and grassland was determined from 191 agricultural fields. A total of 18 nematode genera were detected, including economically important pests, Meloidogyne spp., Heterodera spp. and Pratylenchus spp., each of which were above economic damage thresholds in a significant proportion of the sites (92.4%, 70% and 28.6%, respectively). The detection of the root knot nematode, Meloidogyne minor (6% prevalence), was significant given its recent emergence across the turf grass sector and the prospect of M. minor becoming a common agricultural pest. Analyses of nematode prevalence and abundance highlighted significant associations with grass and cereals, soil types, soil grade (proxy for soil quality) and rainfall levels. Specifically, nematode populations varied between the two major soils (brown earths and gleys), while significant trends for increased nematode diversity and greater prevalence of both Meloidogyne and Pratylenchus with increasing rainfall were also observed. Multivariate analyses were performed to determine interactive effects and the relative importance of the factors affecting nematode populations. Notably, rainfall, in combination with either crop type or soil grade, had a significant effect on nematode abundance and diversity. The findings suggest significant changes in nematode populations have occurred over the last several decades and the possibility that these are linked to changing climate and cropping practices are discussed, as well as future concerns for plant parasitic nematode management.