Evaluation of phenology-based insecticide strategies for fall armyworm (Spodoptera frugiperda) management in maize in India

The invasive fall armyworm (Spodoptera frugiperda J.E. Smith) poses a significant threat to maize productivity in India, yet optimal insecticide application strategies aligned with crop phenology remain underexplored. A comprehensive field investigation was undertaken at the Maize Research Centre, Rajendranagar, Hyderabad, across three consecutive Kharif seasons (2020-2022) to assess the performance of chlorantraniliprole 18.5 % SC (soluble concentrate) (applied at 0.4 ml/L) in controlling the invasive pest Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae), commonly known as the fall armyworm (FAW), in maize. The experimental layout followed a randomized block design, incorporating multiple insecticide application timings based on crop phenology (7, 10, 14 and 20 days after germination) and pest incidence thresholds (5 % and 10 %), in addition to an untreated control for comparison.Among the evaluated strategies, the sequential application of chlorantraniliprole at the V2 (7 DAG) and V4 (14 DAG) vegetative stages proved to be the most effective. This treatment significantly minimized FAW infestation, registering a mean infestation of only 12.33 %, along with the lowest leaf injury rating (1.98) on the modified Davis scale and the highest recorded grain yield (81.30 q/ha). A closely comparable result was achieved with applications at the V3 (10 DAG) and V5 (20 DAG) stages, which showed a slightly higher mean infestation (13.71 %) but identical leaf injury scores (1.98) and a near-equivalent grain yield (81.11 q/ha). The findings underscore the importance of timely insecticide applications during the early vegetative stages, particularly V2 and V4, to suppress FAW populationseffectively and optimize maize productivity. This research highlights the critical role of growth stage-based pest management in enhancing crop health and yield outcomes under FAW pressure.