A model for dry bean yield loss due to rust

Severity of rust ( Uromyces appendiculatus ) and yield of dry edible beans ( Phaseolus vulgaris L.) were recorded for 9 years in west-central Nebraska in fungicidal efficacy trials. A weighted analysis of covariance was used to estimate yield loss due to rust. The model fit the data well ( R 2 =0.94), and the slope over all years had a 19 kg.ha −1 decrease in yield for each 1% increase in severity of rust. Yield response within years occurred only through reduction of rust for most fungicide treatments.