Wheat blast, leaf spot diseases, and grain traits shaped by genotype–fungicide interactions and modulated by weather conditions

Wheat blast and leaf spot diseases present significant challenges for chemical control. This study hypothesized that fungicide efficacy against wheat blast depends on genotype – fungicide interactions and weather conditions, while the use of broad-spectrum fungicides complicates disease-specific assessments. The objective was to evaluate wheat blast, leaf spots, and grain traits as influenced by genotype, fungicide, and environmental conditions. Field trials were carried out during 2016 and 2017 crop seasons using a complete 3 × (7 + 1) factorial arrangement, comprising three wheat genotypes, seven fungicides, and an untreated control. Wheat blast incidence and leaf spot severity were highly correlated, both driven by genotype – fungicide interactions and modulated by weather conditions. High humidity combined with warmer temperatures, which favor fungal infection, reduced the efficacy of chemical control. Grain yield and thousand-grain weight were strongly influenced by diseases and genotypes, though fungicide application had no significant effect. In conclusion, fungicide management strategies should be tailored to specific active ingredients and wheat cultivars, taking environmental conditions into account. Additionally, the use of broad-spectrum fungicides, recommended for both diseases, complicates disease-specific evaluations, particularly when leaf spots are overlooked in wheat blast-focused studies, highlighting the need for integrated disease assessments.