Yield Losses Due to Crown Rust in Winter Oats in Alabama

Abstract

Crown rust is a common disease on winter oats in Alabama. While considered the most destructive disease of oats, little has been done in recent years, with current cultivars, to demonstrate yield losses due to crown rust. Field studies were conducted to determine the effect of fungicides and application timing on crown rust severity and yield. All fungicides reduced crown rust and improved yield. Two fungicide applications were better than a single fungicide application for reducing crown rust. Relative to yield, a single fungicide application during flag leaf development (FS 8-9) was better than a single application during head extension (FS 10.3). When compared with the non-treated control, significant yield gains were obtained with Tilt and Headline in all four years and Stratego YLD in three of four years. Fungicide programs resulted in a broad range of crown rust severities; disease levels were highly related to decreases in yield in each of four years. In two study years, ‘Coker 227’ was more damaged by crown rust, with about 10% yield loss for each unit disease, than was ‘Horizon 270,’ with 2.5 to 4.5% loss. However, in 2013, virulence patterns of the crown rust pathogen shifted and disease on Horizon 270 was greater than that on Coker 227; relative yield losses were also much lower in 2013. Accepted for publication 15 April 2016. Published 4 May 2016.