Distribution of Fusarium wilt and plant-parasitic nematodes associated with cotton in Benin Republic (West Africa)

Cotton plays a major role in the agricultural economy in Benin. However, plant-parasitic nematodes and their association with Fusarium wilt constitutes a key limiting factor in its production. To determine the potential threat of these pathogens to the crop in Benin, a field survey was conducted during 2022 from 50 cotton fields across five agroecological zones (AEZs). At least five fields were surveyed per administrative district, and in each district, 20 plants were evaluated for the incidence and severity of Fusarium wilt on plants leaves. Fusarium was isolated from plant leaves and stems, and nematodes were extracted from soil, followed by morphological identification. Fusarium wilt was present in plant leaves and stems in 22% of fields and nematodes in all surveyed fields. The highest incidence (31.25%) and severity (13.25%) of Fusarium wilt were observed in the western Atacora, whereas northern cotton-growing regions recorded the lowest. Three cotton cultivars were recorded, all of which showed disease symptoms with varying incidence (0–5) and severity (2–3). Eight genera of nematodes were observed: Helicotylenchus, Meloidogyne, Pratylenchus, Rotylenchus, Hoplolaimus, Xiphinema, Rotylenchulus, and Criconemoides. The bar land zone AEZ was diverse in nematode genera and population densities, followed by the central cotton-growing zone. The most abundant nematode genus was Helicotylenchus. (49%) in the food-growing in South Borgou zone followed by Meloidogyne (43%) in the central cotton-growing zone and Pratylenchus (39%) in the bar land zone.