Potential application of Hyptis spicigera for biological control of Striga hermonthica infestation.

Abstract

Food situation has remained insecure and unpredictable in sub-Saharan Africa leading to high levels of cyclic famine and poverty. This has been exacerbated by perennial pest problems, which cause substantial pre- and post-harvest food grain losses. Production of cereal crops is threatened by Striga hermonthica weed known to infest an estimated 46000 ha of land in the traditional food producing areas in western and coastal Kenya. It is against this background that this study was designed to evaluate the efficacy of Hyptis spicigera–maize cropping systems on S. hermonthica infestation and maize grain yield and, generate a recommendation compatible with the target farmer dormains. Results showed that Striga counts were significantly (P < 0.05) reduced where maize was following fallow with H. spicigera. This was most effective in reducing S. hermonthica incidence and increased maize yield from 2.2 to 3.4 T/Ha. Intercropping maize and H. spicigera in the same plot at the same time negatively affected maize growth resulting in reduced maize yields. Indications were that root cuttings of H. spicigera stimulated Striga seed germination while their stubble (stem and leaves) reduced Striga seed bank in the soil. Striga seed bank analysis showed that Striga seed depletion increased with increase in Hyptis bushes with critical Hyptis seeding rate of 3 kg/Ha for maximum reduction in Striga seed bank. The findings of this study have implications for plant protection against S. hermonthica and improvement of cereal crop production in Striga-prone environments. Key words: Striga Incidence, seeding rates, cropping systems, maize yield.