Otimização da pulverização e controle de Phakopsora pachyrhizi na cultura da soja
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Data
2018-07-30
Autores
Negrisoli, Matheus Mereb
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Para o controle da ferrugem asiática da soja (FAS) é necessário a otimização da tecnologia de aplicação de modo a promover incrementos na cobertura da pulverização na região do baixeiro da cultura e melhorar a distribuição das gotas no dossel. Assim, o objetivo deste trabalho foi avaliar o efeito de pontas de jato plano com diferentes inclinações e volumes de calda na otimização da pulverização de fungicidas na cultura da soja, no controle da FAS e sobre a produtividade da cultura. Para isso, foram conduzidos três experimentos durante as safras 2016/17 e 2017/18 em Botucatu, SP envolvendo três pontas de pulverização: jato plano (AXI), jato plano duplo (JGT) e jato plano inclinado (Defy3D) em dois volumes de calda (125 e 250 L ha-1). No experimento 1 foi avaliado em mesa de distribuição volumétrica a uniformidade da distribuição volumétrica dos tratamentos e o espectro das gotas da pulverização pelo medidor de tamanho de partículas em tempo real. No experimento 2 foi realizado a análise quali-quantitativa da pulverização, por meio da deposição da calda na cultura com o marcador Azul Brilhante, e a cobertura da pulverização dos tratamentos em alvos artificiais e natural. Por fim, no experimento 3 foi avaliado a severidade e incidência da FAS, de modo a se determinar a eficácia de controle dos tratamentos, assim como seu efeito sobre a produtividade da cultura da soja. Em ambos os volumes de calda, a ponta JGT obteve menor coeficiente de variação e melhor distribuição da pulverização. Todas as pontas nos volumes de calda mantiveram valores de CV abaixo de 7%, considerado aceitável para os padrões internacionais. O DMV (µm), SPAN e porcentagem de gotas inferiores a 100 µm foram influenciados pela adição do fungicida associado ao adjuvante à calda. Independente da ponta de pulverização e volume de calda, a penetração das gotas da pulverização no dossel foi prejudicada em R2, com baixos valores de deposição e cobertura na parte inferior da planta. Todas as pontas e volumes avaliados promoveram controle eficaz da doença, não havendo incremento no controle com a utilização de um volume de calda maior ou inclinação do jato. Mesmo com redução significativa da deposição e cobertura na região inferior, os tratamentos foram eficazes na redução da severidade da doença. O nível de controle, apesar de parecer eficaz quanto ao número de pústulas e cálculo da área abaixo da curva de progresso da doença (AACPD) pode não ser suficiente para assegurar maior produtividade. A correta definição do volume de calda, principalmente com relação aos diferentes estádios fenológicos da cultura, influencia grandemente a deposição e cobertura da pulverização.
For the control of Asian soybean rust (SBR), an optimization of the application technology is necessary in order to improve spray coverage in the lower part of the crop as well as the spray drops distribution uniformity. Thus, the objective of this study was to evaluate the effect of flat fan nozzles with different inclinations and spray volumes on the optimization of fungicide spraying in the soybean crop, as well as on the ASR control and its effect on the crop yield. For this purpose, three experiments were conducted during 2016/17 and 2017/18 crop seasons in Botucatu, SP. Three spray nozzles were evaluated: flat fan (AXI), double flat fan (JGT) and inclined flat fan (Defy 3D) with two spray volumes (125 e 250 L ha-1). In Experiment 1, the spray distribution uniformity of the treatments was evaluated in a patternator table and the spray droplet spectrum was assessed by a real-time particle size analyzer. In Experiment 2, a quali-quantitative analysis of the spraying was evaluated, assessing spray deposits on the crop with Brilliant Blue tracer, and the spray coverage of the treatments on artificial and natural targets. Lastly, in Experiment 3, ASR incidence and severity were evaluated, in order to determine the treatment control efficacy and its effect on the soybean yield. In both spray volumes, the JGT nozzle provided lowest variation coefficient and better spray distribution. All the spray nozzles and volumes kept CV values below 7%, considered acceptable by international standards. The VMD (µm), SPAN and percentage of droplets smaller than 100 µm were influenced by the addition of fungicide associated with adjuvant to the spray mixture. Irrespective of the spray nozzle and volume, the penetration of the spray droplets into the crop canopy was impaired at R2, with low deposition and coverage in the lower part of the plant. All the spray nozzles and volumes promoted effective control of the disease, with no increment in function of a larger spray volume or spray inclination. Even with significant reduction on deposition and spray coverage on the lower region, the treatments were efficient reducing the disease severity. The level of control, although it seems effective regarding pustules number and area under the disease progress curve calculation, might not be enough to ensure greater productivity. The correct spray volume definition, especially in respect to the different crop phenological stages influences greatly in the deposition and spray coverage.
For the control of Asian soybean rust (SBR), an optimization of the application technology is necessary in order to improve spray coverage in the lower part of the crop as well as the spray drops distribution uniformity. Thus, the objective of this study was to evaluate the effect of flat fan nozzles with different inclinations and spray volumes on the optimization of fungicide spraying in the soybean crop, as well as on the ASR control and its effect on the crop yield. For this purpose, three experiments were conducted during 2016/17 and 2017/18 crop seasons in Botucatu, SP. Three spray nozzles were evaluated: flat fan (AXI), double flat fan (JGT) and inclined flat fan (Defy 3D) with two spray volumes (125 e 250 L ha-1). In Experiment 1, the spray distribution uniformity of the treatments was evaluated in a patternator table and the spray droplet spectrum was assessed by a real-time particle size analyzer. In Experiment 2, a quali-quantitative analysis of the spraying was evaluated, assessing spray deposits on the crop with Brilliant Blue tracer, and the spray coverage of the treatments on artificial and natural targets. Lastly, in Experiment 3, ASR incidence and severity were evaluated, in order to determine the treatment control efficacy and its effect on the soybean yield. In both spray volumes, the JGT nozzle provided lowest variation coefficient and better spray distribution. All the spray nozzles and volumes kept CV values below 7%, considered acceptable by international standards. The VMD (µm), SPAN and percentage of droplets smaller than 100 µm were influenced by the addition of fungicide associated with adjuvant to the spray mixture. Irrespective of the spray nozzle and volume, the penetration of the spray droplets into the crop canopy was impaired at R2, with low deposition and coverage in the lower part of the plant. All the spray nozzles and volumes promoted effective control of the disease, with no increment in function of a larger spray volume or spray inclination. Even with significant reduction on deposition and spray coverage on the lower region, the treatments were efficient reducing the disease severity. The level of control, although it seems effective regarding pustules number and area under the disease progress curve calculation, might not be enough to ensure greater productivity. The correct spray volume definition, especially in respect to the different crop phenological stages influences greatly in the deposition and spray coverage.
Descrição
Palavras-chave
Tecnologia de aplicação, Pontas de pulverização, Volume de calda, Ferrugem asiática da soja, Fungicidas, Application technology, Spray nozzles, Spray volume, Asian soybean rust, Fungicides