https://repositorio.ifgoiano.edu.br/handle/prefix/149 2026-03-12T23:10:18Z https://repositorio.ifgoiano.edu.br/handle/prefix/6313 Título: SUBSTITUIÇÃO DO ACEFATO POR ISOXAZOLINA + PIRETRÓIDE EM UM MANEJO QUÍMICO ROTACIONADO CONTRA Dalbulus maidis, COM CONSEQUÊNCIAS FITOSSANITÁRIAS E PRODUTIVAS, PARA MILHO SAFRINHA Autor(es): Silva, Frederico de Melo Primeiro Orientador: Pereira, Alexandre Igor Azevedo Abstract: The corn leafhopper, Dalbulus maidis (DeLong & Wolcott) (Hemiptera: Cicadellidae), the vector of the corn stunt disease complex, is among the principal constraints to maize production in Brazil, demanding integrated management programs that rotate insecticidal modes of action (MoA). However, experimental comparisons that explicitly connect spray programs to maize phenology while contrasting distinct MoA remain scarce. We evaluated, in the hybrid MG540 grown under rainfed second-season conditions, the agronomic relevance of two sequential foliar spray programs on vector populations, stunt incidence, and grain yield. The trial followed a randomized complete block design with three treatments (T). T1 was an absolute, water-only control. T2 comprised thiamethoxam + lambda-cyhalothrin at VE, three sequential applications of isocycloseram + lambda-cyhalothrin at 5-7 day intervals, one application of profenofos + cypermethrin, and two applications of acetamiprid + lambda-cyhalothrin (at 14-day intervals). T3 followed the same calendar as T2, but replaced isocycloseram + lambda-cyhalothrin with acephate in the three central sprays. Throughout vegetative development, we periodically monitored (per 1 m row) the number of leafhoppers per plant, the percentage of plants with leafhoppers, and the percentage of plants showing stunt symptoms. These metrics were paired with control efficacy (EC%) corrected by the Henderson–Tilton method. At the end of the phenological cycle, grain yield (sacks ha⁻¹; 60-kg sacks) was estimated for each treatment. Both time (spray calendar) and treatment effects were significant for all periodic parameters and their corresponding EC%. T2 sustained more stable suppression during the intermediate window, with a peak around 5-7 days after application of the fourth spray (5-7 DAA4), whereas T3 produced a stronger initial knock-down effect followed by mid-cycle instability. Stunt incidence emerged late, with the hierarchy T1 > T2 > T3, and higher early-outbreak efficacy under T2. For yield, T2 reached 161.19 ± 19.00 sacks ha⁻¹, T3 achieved 138.00 ± 18.00 sacks ha⁻¹, and T1 only 92.00 ± 22.00 sacks ha⁻¹. Overall, the application program embodied by T2 combined consistent vector suppression, mitigation of stunt expression, and high yield. Intensive monitoring from VE to V4, rotation of MoA with substitution toward newer insecticides, and reapplications scheduled between 5-7 days after the third to fifth applications (5-7 DAA3 and 5-7 DAA5) emerge as actionable findings to help growers manage high D. maidis pressure more decisively, protectively, and productively under field conditions. Editor: Instituto Federal Goiano Tipo: Dissertação 2026-02-16T00:00:00Z https://repositorio.ifgoiano.edu.br/handle/prefix/6280 Título: PLANO DE MANEJO COM INSETICIDAS E INDUTOR DE RESISTÊNCIA PARA O CONTROLE DE Dalbulus maidis E FITOPATÓGENOS ASSOCIADOS AO MILHO-DOCE Autor(es): Silva, Adriano de Almeida Primeiro Orientador: Pereira, Alexandre Igor Azevedo 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. Editor: Instituto Federal Goiano Tipo: Dissertação 2025-12-08T00:00:00Z https://repositorio.ifgoiano.edu.br/handle/prefix/6069 Título: ESTUDOS EPIDEMIOLÓGICOS DO COMPLEXO DE ENFEZAMENTOS DO MILHO NO OESTE DO PARANÁ Autor(es): Alvarenga, Letticia Primeiro Orientador: Macedo, Mônica Alves de Abstract: The corn stunt complex represents a growing phytosanitary challenge in Brazil, including the western region of Paraná, where increasing vector pressure and disease severity have been observed. This study aimed to assess the incidence of diseases caused by Spiroplasma kunkelii, maize bushy stunt phytoplasma and maize rayado fino virus (MRFV), monitor the infestation of the corn leafhopper (Dalbulus maidis), and perform molecular detection of these pathogens in summer and off-season corn crops in western Paraná. Sixteen agricultural areas were monitored using yellow sticky traps for vector capture, visual inspections of plants, and molecular analyses for pathogen detection. The highest infestation of D. maidis was observed during the second growing season, particularly in the municipalities of Cascavel and Santa Helena. However, the molecular detection of pathogens and the incidence of symptomatic plants were higher during the first season, especially in Santa Helena, where 43% of the evaluated plants exhibited typical symptoms of the complex. S. kunkelii was the most frequently detected pathogen in the first season, while MRFV predominated in samples. The data revealed significant spatial and temporal variation in vector infestation among municipalities, with a tendency for increasing populations throughout the crop cycle, peaking during the final evaluations. Despite the high infestation levels in several areas, symptom occurrence was uneven, and no direct correlation between leafhopper density and disease incidence was observed. These findings indicate that the occurrence of the maize stunting complex is influenced by multiple factors, such as inoculum pressure, hybrid tolerance, and locally adopted management strategies. Integration of vector population monitoring, visual symptom assessment, and molecular diagnosis proved essential for understanding the local dynamics of the maize stunting complex, as well as for guiding regionally adapted and sustainable management strategies. Editor: Instituto Federal Goiano Tipo: Dissertação 2025-10-22T00:00:00Z https://repositorio.ifgoiano.edu.br/handle/prefix/5907 Título: INTERAÇÃO DE NEMATICIDAS E CULTIVARES DE SOJA SUSCETÍVEIS A NEMATÓIDES NO CONTROLE DE Heterodera glycines E Pratylenchus brachyurus Autor(es): Silva, Liéli Augusta da Primeiro Orientador: Alves, Gleina Costa Silva Primeiro Membro da Banca: Alves, Gleina Costa Silva Segundo Membro da Banca: Barbosa, Marianne Gonçalves Terceiro Membro da Banca: Silva, Lincon Rafael da Abstract: The phytonematodes Heterodera glycines and Pratylenchus brachyurus cause severe damage to the soybean crop, causing high economic losses annually. In this way, control methods have been studied in order to find solutions that integrate into the management of nematodes. Therefore, the present study aimed to evaluate the interaction between chemical and biological nematicides with soybean varieties susceptible to nematodes, in the control of the nematodes H. glycines and P. brachyurus in the soybean crop, in field conditions naturally infested with mixed population H. glycines and P. brachyurus. The trial was carried out in Uberlândia - MG, in naturally infested field conditions with a mixed population during the season 21/22, a factorial scheme was used in a randomized block design, in which factor A were the susceptible cultivars and factor B the nematicides, totaling 8 treatments and 4 repetitions. The treatments were: T1- CZ77I79RSF IPRO (Check); T2-CZ77I79RSF IPRO + Bacillus firmus I-1582 (70ml/60.000seeds); T3- CZ77I79RSF IPRO + Bacillus firmus I-1582 (70ml/60.000seeds); Fluopyram (500 ml via furrow); T4 - CZ77I79RSF IPRO + Bacillus firmus I-1582 (70 ml/60.000 seeds) + Fluopyram (500 ml via furrow); T5- CZ37B51IPRO (check) + check; T6 CZ37B51IPRO + Bacillus firmus I-1582 (70ml/60.000seeds); T7-CZ37B51IPRO + Fluopyram (500 ml via groove); T8 - CZ37B51IPRO + Bacillus firmus I-1582 (70 ml/60.000 seeds) + Fluopyram (500 ml via the groove). The data were submitted to Shapiro Wilk's normality test. Once this was verified, it was identified whether there was a significant difference, and a comparison was made between the means by Tukey's test at 5% probability, using the R program. normal data even after being transformed, the productivity data, by ANOVA it was possible to conclude that there was a significant difference for the A factor, and by the Tuckey test at 5% of significance, the cultivar CZ77I79RSF IPRO had an increase in productivity when compared to the cultivar CZ37B51IPRO . Editor: Instituto Federal Goiano Tipo: Dissertação 2023-06-30T00:00:00Z