Faculty of Natural Resources Management and Agriculture

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Browsing Faculty of Natural Resources Management and Agriculture by Author "Mapuranga, R."

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    Effect of Cowpea Trap Crop on the Control of [Aphis gossypii (Glover)] in Zimbabwean Cotton
    (Asian Journal of Research in Crop Science, 2023-05-11) Jimu, F.; Mapuranga, R.; Mubvekeri, W.; Ngara, B.; Kutywayo, D.
    Cotton aphids are major cotton pests causing significant yield losses of more than 65% in Zimbabwe. Field experiments to investigate the effectiveness of cowpea as a trap crop in reducing aphid pressure on cotton were conducted over three seasons 2010/11 to 2013/14 at Cotton Research Institute (CRI) in Kadoma, and Umguza in Matebeleland North, in Zimbabwe. Incidence of aphid predators on sole cotton, cotton intercropped with cowpea trap crop and the trap crop itself were also assessed. The measurements were aphid scores, aphid predator counts in both sole cotton, intercropped cotton and cowpea trap crop. Seed cotton yield was measured. Aphid scores and predator counts were subjected to Analysis of Variance (ANOVA) using GenStat 14th Edition software. The square root transformation [x + 3/8] was used for scores or counts not normally distributed. At CRI Cowpea trap crop significantly controlled aphids in intercropped cotton better than chemical control using Acetamiprid 20 SP (P< 0.05). Coccinellid grubs (ladybird beetle larval) populations were highest in cowpea trap crop. At Umguza poor germination of cowpea resulted in highest Coccinellid adults (ladybird beetle adults) in intercropped cotton. Yield of intercropped cotton was comparable to yield from plots where Acetamiprid 20SP was used as a standard practice. Farmers can adopt this technology of aphid control in cotton using commercial cowpea variety CBC 3 as cotton aphid trap crop.
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    Efficacy of Spinosad 48SC on the Management of Cotton Bollworms Diparopsis castanea (Hubner) and Herlicoverpa amigera (Hampson) in Zimbabwe
    (Asian Journal of Research in Crop Science, 2023-05-11) Jimu, F.; Mapuranga, R.; Mubvekeri, W.; Kutywayo, D.
    Bollworms management remains one of the major constraints to higher cotton productivity in Zimbabwe. Field trials to investigate the efficacy of Spinosad 48 SC on Diparopsis castanea (Hubner) and Herlicoverpa amigera (Hampson) were carried out for three seasons 2010/11 to 2013/14 at Cotton Research Institute, Kuwirirana, Umguza, and Chizvirizvi in Zimbabwe. A Randomised Complete Block Design with five treatments and four replications was used in this experiment. Three doses of Spinosad 48 SC 40ml/ha, 60ml/ha and 80ml/ha, were evaluated, along with Lambda cyhalothrin 5 EC at 200ml/ha as the standard treatment and the untreated control. Observations on bollworms eggs, larval counts and predator counts. The square root transformation of (x + 3/8) was used for data not following normal distribution. Data were analysed using Genstat 14th Edition. All the three doses of Spinosad 48 SC (40ml/ha, 60ml/ha and 80ml/ha) controlled Diparopsis castanea (Hubner) and Herlicoverpa amigera (Hampson) at CRI, Kuwirirana, Umguza and Chizvirizvi. The highest dose of Spinosad 48 SC of 80ml/ha resulted in the highest yield of seed cotton at CRI and Kuwirirana. All the three doses of Spinosad 48 SC killed predators in the same way as the standard insecticide. Spinosad 48 SC was recommended for registration on control of the two bollworms in Zimbabwe at 80ml/ha dose.