The impact of super-high density olive orchard management system on soil plant-parasitic nematodes in Central and South Italy

Abstract: Super-high density (SHD) olive orchards are spreading in Italy. The aim of the present study was to assess the effect of SHD olive orchards on soil plant-parasitic nematode community in five sites located in the main areas suitable for the cultivation of the olive orchards (Apulia, Tuscany, and Sicily) with different soils, climate, and consequently various cultivars. In each site, the SHD management system was compared to the adjacent olive orchard traditional system, in which the same soil management was applied. Although the free-living nematodes (bacterial and fungal feeders and their predators) were prominent in each site, the high ratio plants/hectare, the different cultivars than traditional, and a higher irrigation requirement favoured the plant-parasitic families of Telotylenchidae, Paratylenchidae, Meloidogynidae, and Criconematidae than Longidoridae, Heteroderidae, and Pratylenchidae in SHD system. The ratio Pp/(B + F) was significantly higher in SHD than in the traditional olive orchard system in sites already stressed by summer droughts and by conventional soil management. Using a conservative and sustainable soil management might prevent the plant-parasitic nematode increase.