Survey of Soil Nematodes in Vegetable Farms of Ogun State, South West Nigeria

This study surveys the diversity and community structure of soil nematodes in vegetable production farms in Ogun State, located in Nigeria's South West geopolitical zone. Plant-parasitic nematodes are significant constraints on vegetable yields in West Africa, and understanding nematode community composition in farmers' fields is important for guiding management. Soil samples were collected from 25 vegetable farms across Abeokuta North, Ifo, and Odeda local government areas using a systematic grid design. Nematodes were extracted by the Baermann funnel technique and identified to genus level under a light microscope. Plant-parasitic nematodes were distinguished from free-living taxa. A total of 34 nematode genera were identified. Plant-parasitic genera dominated on 72 percent of farms sampled. Meloidogyne spp. was the most frequently encountered plant parasite (recorded on 84% of farms), followed by Pratylenchus spp. (68%) and Helicotylenchus spp. (52%). Meloidogyne infection was associated with visible root galling in tomato and pepper crops on 61 percent of positive farms. Bacterivore nematodes were the most abundant free-living guild, reflecting soil organic matter inputs from manure applications. The nematode enrichment index indicated elevated nutrient cycling activity at farms with organic inputs. The study identifies Meloidogyne management as the highest priority nematological challenge for Ogun State vegetable farmers and recommends cover cropping with Tagetes spp., solarisation, and certified nematode-free transplant nurseries as low-cost management strategies. Keywords: soil nematodes, Meloidogyne, vegetable farms, Ogun State, plant parasites.