Phytonematodes Associated with Kenaf (Hibiscus cannabinus L.) in Southwest Nigeria

The study identified the plant-parasitic nematodes associated with kenaf in selected locations in southwest Nigeria. A survey was conducted in kenaf fields in Ile-Ife and Ikenne, Ibadan and Ilora in September, 2022. The soil sampling procedure involved the collection of samples from 30 distinct locations proximate to the plant roots. Plant-parasitic nematodes (PPNs) were extracted, identified and counted. The frequency of occurrence (FO) and population densities (PD) of the extracted nematodes were calculated. Four genera of PPNs were associated with kenaf in all study locations. These were Meloidogyne, Pratylenchus, Helicotylenchus, and Tylenchus. In Ile-Ife, Meloidogyne had the highest population density per 200 ml soil (72.7%), followed by Helicotylenchus (21.4%), while the lowest density was recorded for Tylenchus (2.0%). In Ikenne, the highest density was recorded for Meloidogyne (47.3%), followed by Pratylenchus (27.9%), and Helicotylenchus (24.4%). The lowest nematode density was recorded for Tylenchus (0.5%). In Ilora, the highest density was recorded for Meloidogyne (66.9%), followed by Helicotylenchus (23.9%), while the lowest density was recorded for Tylenchus (1.4%). The survey in Ibadan showed that nematode with the highest density was Meloidogyne (61.1%), followed by Helicotylenchus (28.0%), while the least density was recorded for Tylenchus (1.3%). This study concluded that four genera of PPN were associated with kenaf in Ikenne, Ile-Ife, Ilora and Ibadan. These were Meloidogyne, Helicotylenchus, Pratylenchus and Tylenchus. The most abundant was Meloidogyne. Therefore, in the management of PPN genera that may impact kenaf production in southwest Nigeria in kenaf, more emphasis should be placed on root-knot nematodes.