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Plants infested with root-knot Nematodes show stunted growth and yellowing of leaves. Root systems develop the characteristic knots or galls (swellings). The severity of the symptoms depends on the number of nematodes and the plant type. Plants heavily infected can develop symptoms characteristic of nutrient deficiencies. In the field, infestation usually occurs in patches. Root-knot nematode causes high economic damage to farmers worldwide.
At optimal temperatures, the life cycle of Meloidogyne spp. takes about 37 days to complete. Temperatures vary slightly between the different species and the host in question. Juveniles penetrate root tips and initiate the development of giant cells in root tissues, resulting in the characteristic galls. The knots in the roots impair water and nutrient transport, causing the yellowing and wilting of leaves, as well as stunted growth. Getting rid of the nematode through means of crop rotation is difficult because of the wide host range of Meloidogyne spp.
In the case of tomato, poultry manure or organic waste are effective to control populations of root‐knot nematodes. Roots are less damaged, plants show more growth and fruit yield increase significantly. Bacterial treatments of soils and seeds with biopesticides containing Pseudomonas Fluorescens, Pasteuria penetrans or Bacillus thuringiensis also work. Nematode-feeding fungi (Arthrobotrys spp. and Monacrosporium spp.) or fungi parasitizing on eggs and females (Pochonia chlamydosporia and Paecilomyces lilacinus) are another solution.
Always consider an integrated approach with preventive measures together with biological treatments if available. Successful approaches to control of nematodes rely on integrated pest management strategies. Nematicides containing carbofuran, oxamyl and fenamiphos can be applied to the soil at pre-planting.