Interannual variability of planting-date effects on Fusarium verticillioides grain colonization and fumonisin contamination in maize

Fusarium ear rot, primarily caused by Fusarium verticillioides , and the associated fumonisin contamination represent major sanitary constraints to maize ( Zea mays L.) production worldwide. Previous single-season evidence under Argentine conditions indicated that late planting enhances fungal colonization and fumonisin accumulation in maize grains. Here, we evaluated the interannual variability of these planting-date effects through a multi-year field analysis conducted across three independent growing seasons (2020–2024). F. verticillioides grain colonization, fumonisin contamination, grain yield, and nutritional composition were assessed under contrasting planting dates (early vs. late) in San Antonio de Areco, Buenos Aires, Argentina. Across seasons, late plantings consistently exhibited higher F. verticillioides grain colonization, accompanied by markedly increased fumonisin concentrations, whereas early plantings showed lower sanitary pressure and higher yields. However, the magnitude of these responses and the relationship between fungal abundance and fumonisin accumulation varied substantially among years, indicating strong modulation by environmental conditions. Grain nutritional composition remained comparatively stable across planting dates and seasons. Overall, these results demonstrate that while the direction of planting-date effects on maize sanitary status is maintained across years, their intensity is highly dependent on interannual climatic variability. Under the evaluated conditions, early planting emerged as the most reliable strategy to reduce fumonisin risk while sustaining productivity in maize cropping systems.