Maize production is severely reduced by the parasitic weed striga in nitrogen depleted soils of sub-Saharan Africa. Short duration planted fallows with leguminous trees, shrubs, and green manuring with foliar biomass of trees and shrubs were examined for their potential to control striga, in addition to replenishing soil fertility. Some Senna spp., Desmodium distortum and Sesbania spp. were found to induce striga germination in laboratory tests. Short-duration Sesbania sesban fallows (0.5 to 3.0 years) reduced infestation of Striga asiatica in eastern Zambia and Striga hermonthica in western Kenya, and increased yields of subsequent maize. The fallows reduced striga infestation by improving soil fertility and probably depleting the striga seed bank in the soil by trees acting as false hosts. Green manuring with imported high quality foliar biomass of species such as Tithonia diversifolia and sesbania increased maize yields and contributed to some reduction of striga by increased nitrogen supply in the root zone. Unlike nitrogen fertilizers, phosphorus fertilizers did not influence striga infestation, but on p- deficient soils p fertilization is essential to realize the potential benefits of agroforestry systems. An integrated strategy is suggested to combat striga, including regular hand-pulling of striga before flowering and adequate nutrient supply through organic and inorganic sources.

English

0103|AL-Maize Program|AGRIS 0102|AJ

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