Control of Cowpea (Vigna unguiculata L. Walp) Diseases with Intercropping of Maize (Zea mays L) and Spray of Plant Extracts

Abstract

Field experiment was conducted to evaluate the effect foliar spray of aqueous extracts of Datura stramonium, Ricinus communis and Jatropha gossypifolia at three concentrations (65 50 and 30%) on cowpea anthracnose disease caused by Colletotrichum lindemuthianum in sole cowpea and cowpea / maize intercrop. The total area of the farm was 270m2 and cowpea population in each cropping system was 324 stands at a spacing of 60x30 cm while the population of maize in the cowpea/maize intercrop was 162 stands at a spacing of 90x60 cm. Spraying of the plant extracts started two weeks after planting (WAP) and continued until 8 WAP. The extract of D. stramonium reduced the incidence and severity of the disease most compared to other extracts. Similarly, the disease incidence in cowpea/ maize intercrop was lower than in sole cowpea. The disease incidence at 65, 50 and 30% concentrations on pooled mean for the sole crop were 11, 15 and 21% whereas that of intercrop plants were 9, 12 and 16%  respectively. The percentage of normal seeds obtained in the study was concentration dependent being highest at 65% in all the extracts and was higher in intercropped (95%) than the sole crop (93%).Similarly, fungal infection on seeds was lower at all concentrations compared to the control. The study therefore shows that extracts of the plants and intercropping of non-host reduced incidence and severity of anthracnose infection with corresponding increase in yield.