Nematode-suppressive and plant growth-enhancing effects of Citrus spp. derivatives against Meloidogyne incognita on tomato

Plant-based derivatives (powders, pellets or extracts) are amongst the most effective types of organic soil amendments for the management of root-knot nematodes (Meloidogyne spp.). The objective of this study was to examine the effect of derivatives (juice, powder and oil) of fruits of several Citrus species (sweet orange, lemon, lime, mandarin and grapefruit) on the reproduction of Meloidogyne incognita race 2 on susceptible tomato plants, and on the vegetative growth of the crop under glasshouse conditions. Results show that juices of sweet orange, and possibly also lemon, applied as soil amendments either before planting or after planting, can significantly suppress the build-up of damaging root population densities of M. incognita on infected tomato plants, limit root galling and improve plant growth. Data confirm the nematode-suppressive and plant-growth enhancing effects reported for Citrus fruit-based plant derivatives, applied either as a compost, powder, extract or pellet.