Evaluation of Cultural Practices for Control of Cercospora Leaf Spot on Groundnut in Zamfara State, North West Nigeria

Cercospora leaf spot complex, caused by Cercosporidium personatum and Cercospora arachidicola, remains a primary biotic constraint on groundnut (Arachis hypogaea) production in the semi-arid North West zone of Nigeria. Chemical fungicide management is often cost-prohibitive for smallholder groundnut farmers in Zamfara State, making evidence-based cultural practices an attractive management alternative. This study evaluated the effectiveness of four cultural management practices, including planting date adjustment, plant population modification, crop residue management, and intercropping with sorghum, on Cercospora leaf spot incidence and severity in groundnut farms across three local government areas of Zamfara State over the 2023 and 2024 growing seasons. A factorial experiment arranged in randomised complete blocks evaluated the main effects and interactions of the tested practices. Early planting combined with residue removal reduced leaf spot severity by 52 percent compared to late planting with residue retention. Intercropping with sorghum at a 1:2 ratio reduced leaf spot area under the disease progress curve by 38 percent, attributed to altered microclimate conditions limiting leaf wetness duration. Reduced plant population improved canopy aeration and was associated with a 29 percent reduction in leaf spot severity relative to dense planting. An economic analysis favoured the early planting with residue removal combination as the most accessible and cost-effective strategy for resource-limited farmers. The study provides evidence-based cultural management guidelines relevant to semi-arid groundnut production in North West Nigeria. Keywords: groundnut, Cercospora leaf spot, cultural management, Zamfara State, intercropping.