Incidencia y severidad del achaparramiento, y evolución temporal y espacial del vector Dalbulus maidis en maíz de segunda en el litoral oeste de Uruguay

Maize (Zea mays) is the second most widely planted summer crop in the country, accounting for 15–20% of the total cultivated area. In recent years, second-crop planting has gained importance due to the development of hybrids capable of achieving high yields with late grain-filling periods and tolerating late planting dates, which allow the crop's critical growth stage to align more favorably with environmental conditions. These characteristics make the crop a profitable, lower-risk alternative. However, a growing problem has emerged regarding maize stunting, a disease linked to the presence of the vector Dalbulus maidis. The objective of this study was to compare vector abundance between two second-crop fields with different planting dates; characterize the vector's temporal dynamics and spatial distribution within the field; quantify the incidence and severity of stunting at various crop stages; and analyze the relationship between these factors and the onset and progression of symptoms. The study was conducted at two sites, Young and Paysandú during the 2024/2025 growing season. Vector abundance was estimated using systematically distributed yellow sticky traps, while stunting incidence and severity were assessed throughout the crop cycle by monitoring associated symptoms on both plants and ears. The results showed a progressive increase in the D. maidis population as the crop matured, a homogenization of spatial distribution within the field at high population densities, and an association between vector abundance and disease expression, particularly regarding the early onset and progression of symptoms. The study concludes that the vector's population dynamics and spatial distribution influence the development of maize stunting, highlighting the importance of early monitoring as a key tool for decision-making in crop management.