Yield Loss Associated with Soya Bean Rust (Phakopsora pachyrhizi Syd.) in Uganda

Studies were conducted to quantify the yield loss attributable to soya bean rust, a relatively new disease in Uganda. This was carried out for three consecutive seasons in the central, eastern, northern and western parts of the country, using three commercial varieties (Nam 1, Nam 2 and Namsoy 3) and two elite varieties (UG-5 and GC-00138-29). The commercial varieties recorded higher yield losses (26.9–36.3%) and higher rust severities >50%, whereas the elite varieties recorded lesser yield losses of <10% and rust severities of <30%. Yield losses were highest in the central region (22.9%), and lowest in the northern region (15.1%). Yield losses differed significantly between seasons and were associated with reduction in seed weight and filled pod per plant