Abstract:
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.
