The effect of crop rotation and tillage practice on Fusarium crown rot and agronomic parameters of wheat in South Africa

Fusarium crown rot (FCR) of wheat (Triticum aestivum) is a stubble-borne disease of global concern and a known yield-limiting factor in the Western Cape Province of South Africa. Disease management options is limited, with a focus on crop rotation and tillage, the effect of which has not yet been quantified locally. Crop rotation and tillage practices were, therefore, investigated in two wheat production areas of the Western Cape over two years (2020 and 2021) to determine its effects on FCR disease- and agronomic parameters of wheat. Crop rotation with non-host crops, including annual medics (Medicago spp.), canola (Brassica napus) and lupin (Lupinus spp.) significantly reduced FCR disease incidence and severity, while increasing grain yield and quality over the two-year study period. Significant negative correlations (P < 0.05) were established between FCR disease incidence and – severity with grain yield and – quality. Tillage practices were comprised of conventional tillage (deep soil disturbance with a plough), minimum tillage (shallow tine tillage), no tillage (no primary soil disturbance, tine planter) and zero tillage (no primary soil disturbance, disc planter). Zero tillage decreased FCR incidence and disease severity, without impeding wheat grain yield and quality. Better soil water conservation later in the season, along with shallower seeding depth in zero tillage, contributed to FCR disease management. Crop rotation with non-host crops, combined with zero tillage can, therefore, be integral to FCR disease management strategies.