African Journal of Biotechnology Vol. 4 (10), pp. 1034-1039, October 2005          
ISSN 1684–5315 © 2005 Academic Journals

Full Length Research Paper

Evaluation of fallow and cover crops for nematode suppression in three agroecologies of south western Nigeria

J. A. Adediran*, A. A. Adegbite, T. A. Akinlosotu, G. O. Agbaje, L. B. Taiwo, O. F. Owolade, and G. A. Oluwatosin

Institute of Agricultural Research and Training, Obafemi Awolowo University, PMB 5029, Moor Plantation, Ibadan, Nigeria.

*Corresponding author. E-mail: jadediran@yahoo.co.uk.

Accepted 25 July, 2005

A study was conducted in three agroecological zones of south-western Nigeria to evaluate the effect of siam weed (Chromolaena odorata) and mucuna (Mucuna utilis) cover/fallow crops on plant-parasitic nematode population. The natural bush regrowth was used as control. Plant-parasitic nematodes were identified and counted during the fallow periods. Eleven genera of nematodes were identified and three (Meloidogyne, Pratylenchus, and Helicotylenchus) species were predominant across the trial locations. Other important genera present were Scutellonema, Tylenchorhynchus and Rotylenchus species. Nematode population densities of pre-crop were lowest in Alagba soil (Rhodic lixisols) at Ikenne in the wet forest zone of Nigeria. The populations in Iwo soil (Rhodic haplustalf) at Ibadan, a dry forest zone was lower than in the Temidire soil (Plinthic luvisol) at Ilora in the derived savannah of south-western Nigeria. There was significant suppression of nematode population densities under the different crops as the fallow period increased. The population reduction in the different locations depended on the nematode species and the cover crops. The natural bush re-growth had the least effect on the nematode suppression at the end of the fallow period. On the average, siam weed fallow reduced nematode population densities by 67-79%, mucuna by 64-72% and the natural bush by 30-49% across the trial locations. For effective nematode suppression with fallow cropping, proper determination of the principal nematode species predominant in an environment is essential.

Key words: Cover crop, fallow crop, nematode population, nematode species, nematode suppression, soil type.