Battling Wheat Rust in South Africa: Challenges and Strategies

Abstract

Rust diseases are seasonal in occurrence but remain a threat to wheat production in South Africa. Adaptation of local races for pathogenic variability, the incursion of exotic variants, the successful survival of pathogens between cropping seasons, susceptibility of some varieties, and favourable environmental conditions, all contribute to rust incidence. Rust surveillance and race typing of Puccinia graminis f. sp. tritici ( Pgt ) and P. triticina ( Pt ) have been conducted since the 1980s, with P. striiformis f. sp. tritici ( Pst ) being added in 1996. To support race phenotyping, molecular characterisation of key isolates was initiated in 2007. Between 2007 and 2022, 11 new Pt races, 8 new Pgt races, and 1 new Pst race confirmed a continued evolution of South African wheat rust populations. Isolates of important races are used for rigorous germplasm evaluation and risk assessment of commercial varieties. Although resistance is the management method of choice, fungicides are regularly applied against a panel of fungal pathogens, likewise protecting crops against rust. Yield loss studies, genetics of resistance, germplasm enrichment, marker development and application, support to breeding companies, chemical control, and the communication of rust data and relevant information, are themes contributed by stakeholders combatting the wheat rusts in South Africa. Information © The Authors 2024