ISOXAZOLINA E PIRETRÓIDE EM PRÉ-MISTURA EM UM MANEJO QUÍMICO ROTACIONADO CONTRA Dalbulus maidis

Abstract

The corn leafhopper, Dalbulus maidis (Hemiptera: Cicadellidae), a vector of the maize stunt complex, is a major constraint to maize production in Brazil and requires integrated management with rotation of insecticide modes of action (MoA). Using the MG540 hybrid under rainfed second-season conditions, we evaluated two sequential foliar spray programs for their effects on leafhopper populations, stunt incidence, and yield. The trial followed a randomized complete block design with three treatments: T1 (water), T2 (a schedule with thiamethoxam + lambda-cyhalothrin at VE, three mid applications of isocycloseram + lambda-cyhalothrin, followed by profenofos + cypermethrin and acetamiprid + lambda-cyhalothrin), and T3 (the same schedule, replacing isocycloseram + lambda-cyhalothrin with acephate in the three mid applications). During the vegetative stage, we monitored leafhoppers per plant, the percentage of plants with leafhoppers, and plants with stunt symptoms per 1 m row, and estimated control efficiency (CE%) using the Henderson–Tilton correction. Application timing and treatments significantly affected all periodic variables and CE%. T2 provided the most stable suppression during the intermediate period (peak at 5–7 DAA4), whereas T3 showed a stronger initial knockdown but later instability. Stunt incidence increased late in the season, with the ranking T1 > T2 > T3 and superior early outbreak performance for T2. Yield reached 161.19 ± 19.00 bags ha⁻¹ in T2, 138.00 ± 18.00 in T3, and 92.00 ± 22.00 in T1. Overall, T2 combined consistent vector suppression, reduced stunt incidence, and higher yield, highlighting the value of intensive monitoring at VE–V4, MoA rotation, and strategically timed reapplications.