Populations of Derived-parasitic Nematodes on Sweet Potato (Ipomoea batatas) Cultivated Fields in Offa, Offa Local Government Area, Kwara State, Nigeria

Abstract

 This study was aimed at ascertaining the soil medium and stems of the test plant to determine the populations of derived-parasitic nematodes associated with sweet potato in Offa, Kwara South, Kwara State. Three sweet potato fields monoculture designated sites-F1, F2 and F3 were randomly selected for the study. Soil was collected between 6-7:30 am each day once every seven days for four months. Twenty-five soil and Twenty-five stems samples were collected from each sweet potato field making a total of one hundred and fifty samples. The soil was collected using hand trowel while Cutlass was used in collecting stems. The sieve plates technique was employed for nematode extraction, and nematodes were identified by the use of a pictorial key. A total of 650 nematodes representing 11 genera were recovered from soil and stem samples. Root Knot/Meloidogyne species 73 (16.3%) had the highest prevalence followed by Cyst nematode/Heterodera species 65 (14.5%) while Stem Lesion/Aphelenchoides basseyi species 2 (0.4%) showed the least prevalence in soil. However, Stem Lesion/Pratylenchus species was reported more often than any other species in stems with a total affluence of 51 (25.2%) followed by Burrowing nematodes/ Radopholus similis species with 44 (21.8%) while Ditylenchus dipsaci species occurred less than all other species with 10 (5.0%); an observation which is ascribed to a nematodes survival strategy. The result shows that soil nematodes are an important pest of sweet potato in the Offa Local Government Area. Others may include, Bursaphelenchus xylophilus, Rotylenchulus reniforms, Xiphinema index, Necobbus aberrans, Aphelenchoides basseyi and Globodera spp). Hence, should be considered in pest control programs