Effect of variety and nitrogen fertilization on insect pest incidence in Sorghum in the Sudan Savanna of Ghana.
Paul B Tanzubil
Studies were conducted at Yinduri in the Sudan Savanna zone of Ghana to evaluate the effects of nitrogen (N) fertilization on insect infestation and damage to Kapaala,( an improved Sorghum variety released by the Council for Scientific and Industrial Research (CSIR)) and Kundabua, the popular land race grown by farmers in the study area. Both varieties supported similar levels of shootfly (Atherigona soccata) attack (deadhearts) but N application increased Dead Heart prevalence in a dose-dependent manner, the increase being more pronounced on Kapaala. Kundabua supported significantly lower mrid bug (Eurystylus oldi) population and thus suffered lower grain quality loss (viability, grain mass) than Kapaala. Application of N to the crop increased infestation and damage by headbugs as was the case for shootfly. Kapaala produced significantly higher yield. The grain yield also increased with N application from 1.08 t/ha at 0 N to 1.48 t/ha at 100 N for Kapaala compared to 0.95 t to 1.16 tons/ha for Kundabua. These studies confirm the higher yield potential of the improved variety as well as its greater susceptibility to head bugs, probably the most important panicle pest of Sorghum in Ghana today. The importance of N fertilizers to increased Sorghum production was also demonstrated with a caution to limit application rate to below 50 kg to minimize adverse effects of insect pests and maintain or improve grain quality.