When a weed can be a crop
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CTA. 1997. When a weed can be a crop. Spore 68. CTA, Wageningen, The Netherlands.
Permanent link to this item: http://hdl.handle.net/10568/48670
Women farmers across Africa have developed techniques for managing plant species that, under certain circumstances, could be perceived as weeds. For example, once established in the soil cocoyam tubers will sprout rapidly and compete vigorously...
Women farmers across Africa have developed techniques for managing plant species that, under certain circumstances, could be perceived as weeds. For example, once established in the soil cocoyam tubers will sprout rapidly and compete vigorously with planted groundnut. To avoid competition with their crops, women farmers in Cameroon cut back the leaves of the cocoyam to arrest its growth and allow the groundnut crop to flourish. But, once the groundnut has been harvested, the cocoyam is left to grow among the succeeding cassava crop since there is little competition between the two species. Water leaf (Talinum triangulare) is another species which, if left unmanaged, acts as a weed in cultivated fields. But it can be eaten as a leaf vegetable and some farmers remove the majority of water leaf plants to reduce competition with their cultivated crop and leave enough to be used for home consumption. Chromolaena odorata was introduced to West Africa early this century With its rapid vegetative development and production of large numbers of airborne seeds this weed has quickly established itself across large areas of the region. Once established it develops into a dense thicket, which can be exceedingly troublesome to farmers. But the plant has now become an important component of the short fallow, slash-and-burn cropping system. As a fallow species, C. odorata provides large quantities of nutrient-rich humus which improves the texture and mineral content of the soil. An added advantage is its successful suppression of another extremely problematic and noxious grass weed, Imperata cylindrica. Although Chromolaena can offer an advantage compared to Imperata, it has led to a heavier workload for women and children responsible for weeding crops. This has followed the general pattern in the shift of dominance in weed species as fallow periods become shorter. Researchers have been told by women farmers that the easier-to-weed species such as Triumfetta cordifolia and Trema orientalis, are being replaced by species such as Ageratum conyzoides and Sida rhombifolia, which are far more labour intensive to weed. The challenge for researchers is to develop integrated weed management strategies which will make a real difference in the lives of women farmers and, in the case of Chromolaena, to reduce its negative effects during the cropping cycle and enhance its soil improvement properties during the fallow phase. IITA PMB 5320 Ibadan NIGERIA