Weed Flora of a Maize/Cassava Intercrop under Integrated Weed Management in an Ecological Zone of Southern Guinea Savanna of Nigeria

摘要

Weed flora of different management techniques under different cropping systems have been reported but no sufficient information on weed flora of integrated weed control method in maize/cassava intercrop in southern Guinea savanna of Nigeria. This study assessed the weed flora and relative frequencies of weeds in a maize/cassava intercrop under integrated weed management involving two pre-emergence herbicides (Primextra and Galex, each at 2.5 kg/ha alone or with one or two supplementary hoe-weeding, at 6 weeks after planting (WAP) or 6 and 12 WAP, a hoe-weeded check (hoeing at 3, 6 and 12 WAP) and a weedy control. A total of 41 weed species belonging to 35 genera and 19 families comprising of Poaceae, Euphorbiaceae, Asteraceae, Rubiaceae, Cyperaceae among others were encountered in the experimental plots during 2002 and 2004 cropping seasons. The very abundant weed species included Paspalum obiculare Forst, Digitaria horizontalis Willd and Brachiaria deflexa (Schumach) while those with moderate abundance were Bulbistylis arbotiva (Steudel), Cleome viscosa L., Croton lobatus L., Dactylocternium aegyptium (L) P. Beauv., Tridax procunbens L. and Vernonia galamensis (Cass.) Less. The remaining weed species had rare abundance. The relative frequency of the weed species was generally reduced under all the weed control treatments except Paspalum obiculare whose relative frequency was consistently high in all the assessment periods under all the weed control treatments.