Diagnostic Study of Planting Time on Sorghum Stalk Borer Infestation and Damage in West Hararghe, Oromia Region, Ethiopia

Abstract

Sorghum is the first most important cereal crop in West Hararghe. However, national figure of grain production still remains below than the world's average grain production per unit area due to different biotic and a biotic factor. Among the biotic factors, stalk borer was considered to be the most important insect pests of sorghum and maize in all areas of the country. As a management option different scholars were recommended sowing date. But there was conflicting report on the relationship between sowing time and borer infestation and damage. It was very crucial to identify the better days of sowing in the zone to reduce pest infestation and increase yield of the crop. Thus, this experiment was designed to evaluate the effect of sowing date on infestation of sorghum stalk borer. Chiro varieties was used for experimentation and sown at seven days interval for six weeks starting from 1st onset of rainfall. The treatments were arranged by RCBD design with three replications. Each treatment had a control plot that treated with insecticide chemicals such as carbaryle powders and Alpha cypermethrine. Based on combined analysis results, mean percent infestation was not shown significant variation (P<0.05) over location but highly significant at (P< 0.001) over years. The percent stalk borer incidence on untreated treatment was shown highly significant at (P< 0.001) on both over years and over location. Length of the feeding tunnel and exit holes in sorghum stem and leaves were significantly higher in earlier planted crop than delayed sorghum. As a general, chemicals treatment with early planting double the grain yield at Hirna sub site but, based on pest infestation status late planting was recommended at both location (Mechara and Hirna) to reduce pest infestation and damage.