INVESTIGATION OF PLANT-PARASITIC NEMATODES OF YAM IN SELECTED YAM FARMS IN TWO LOCAL GOVERNMENT AREAS OF RIVERS STATE

Investigation of plant-parasitic nematodes of yam in selected yam farms in two Local Government Areas of Rivers State was conducted. A total of 22 yam farms were selected and assessed, 12 from Emohua and 10 from Etche Local Governemnet Areas (LGA). Two tubers of yam ready to be harvested were randomly selected and the soil around it were collected, bagged individually and transported to the laboratory for bioassay. Sieve plate nematode extraction technique was used for extraction of nematodes from the tubers and soil. The purpose of the study was to identify the plant parasitic nematodes that affect yam in the selected zone and likely to predict if nematode was a predisposing agent to yam rot in the study area. The results showed that in Emohua LGA, Meloidogtne spp. with mean population of 90.407±0.543 were the most prevalent species in the soil samples followed by Heterodera spp. with 38.622±0.891 and Pratylenchus spp. with 26.322±0.962 while in the roots and yam tuber Meloidogyne spp. had the most prevalent species with mean population of 69.510±0.907, followed by Scutellonema spp. with 15.651±2.201 and then Ditylenchus spp. with 13.7651±2.644. Also, in Etche LGA, Meloidogyne spp., Tylenchulus spp. and Rotylenchulus spp. had the most prevalent species in the soil with mean populations of 24.920±0.479, 22.426±1.093 and 20.202±0.828 respectively. In the roots and yam tubers, Scutellonema spp., Meloidogyne spp. and Heterodera spp. in that order had the most prevalent species with mean populations of 17.814±0.253, 13.240±0.286 and 10.619±0.401 respectively. Data analysis showed that plant-parasitic nematodes recovered from the soil and roots/yam tuber were statistically significant at P<0.05. These showed that the presence of these plant-parasitic nematodes in the study area suggests that they are important pests of yams even though their presence is not noticed by farmers. They could be attributed to poor yield in yams in the study areas.