First Report of Rust Caused by Puccinia arachidis on Peanut in South Carolina

Abstract

Puccinia arachidis Speg. (phylum Basidiomycota, class Pucciniomycetes) causes rust on peanut (Arachis hypogaea L.) and is a biotroph. In September 2016, several plants exhibiting numerous rust-colored pustules characteristic to peanut rust (Subrahmanyam 1997) on abaxial leaf sides were observed in two plots (12.19 × 12.67 m) at approximately 5% incidence of total leaflets (≈3% severity) in a localized area of approximately 2 × 2 m in a peanut field in Blackville, SC (Barnwell County) on the commercial variety ‘Georgia 12Y’. Also in September, identical symptoms were observed in a localized area of approximately 3 × 3 m (80% leaflet incidence, 40% severity) in a commercial field (≈40 hectares) of ‘Georgia 06G’ (industry-standard runner variety) in Orangeburg County, SC. Both locations were managed under reduced fungicide programs. The Barnwell County location received four applications of chlorothalonil alone as part of a separate disease study, whereas the Orangeburg County field received five chlorothalo...