PLANO DE MANEJO COM INSETICIDAS E INDUTOR DE RESISTÊNCIA PARA O CONTROLE DE Dalbulus maidis E FITOPATÓGENOS ASSOCIADOS AO MILHO-DOCE

Abstract

The corn leafhopper Dalbulus maidis (Hemiptera: Cicadellidae) is the main vector of yield-limiting pathogens in sweet corn in Brazil. The use of new-generation insecticides combined with application frequency and different active ingredients, as well as plant defense inducers, is still an underutilized control strategy. These practices are aligned with Integrated Pest Management (IPM) and can reduce the negative impacts caused by maize rayado fino virus, one of the major pathogens in sweet corn transmitted by D. maidis in the state of Goiás, Brazil. This study evaluated the effectiveness of integrated crop-protection strategies involving the number of weekly applications of insecticidal products with different modes of action, with or without the resistance inducer acibenzolar-S-methyl (ASM), for controlling D. maidis and mitigating virus-related damage in the sweet corn hybrid GSS0227, as well as their effects on yield and industrial recovery under real field conditions. The experiment followed a randomized complete block design with eight treatments in a 3×2+2 factorial arrangement, comprising one, two, or three weekly insecticide application schedules, the absence or presence of ASM, and two controls (negative and positive). The assessed variables were the number of leafhoppers per plant, visual symptoms of maize rayado fino virus, yield (t ha⁻¹), and industrial recovery (%). Significant effects of application intensity and ASM, as well as their interaction, were observed for vector density and yield components. The negative control showed the highest infestation (>2.8 leafhoppers per plant), the highest symptom incidence (>50%), and the lowest yield (<18 t ha⁻¹) and industrial recovery (<35%). Insecticide-only programs provided partial control, reducing the population to 2.1–2.6 leafhoppers per plant and symptom incidence to 35–45%, with modest gains in yield (20–23 t ha⁻¹) and industrial recovery (38–43%). In contrast, adding ASM increased management efficiency, reducing infestation to 1.7–2.0 leafhoppers per plant and symptom incidence to 25–30%, while increasing yield (23–25 t ha⁻¹) and industrial recovery (44–48%). The best performance was achieved by the positive control program, which combined regular applications with systematic ASM use, reaching <1.6 leafhoppers per plant, ~22% symptomatic plants, yield >25 t ha⁻¹, and industrial recovery >48%. We conclude that integrating insecticide application intensity with the strategic use of ASM maximizes D. maidis control, reduces maize rayado fino expression, and simultaneously increases sweet corn yield and industrial recovery, representing a high-impact approach for IPM programs in regions under strong virus pressure.