It was possible to reduce the volume rate of application with electrostatic spraying without adversely affecting the control of the guava psyllid. © 2016 Society of Chemical Industry.

RESUMO -A lagarta-do-cartucho (Spodoptera frugiperda) é uma praga-chave na cultura do milho, e aplicações de inseticidas têm sido necessárias para reduzir a população do inseto. O controle desta praga tem sido difícil porque a lagarta encontra-se comumente protegida no interior do cartucho, o que pode reduzir a deposição e eficácia do inseticida. Portanto, este trabalho objetivou avaliar o efeito de taxas de aplicação, pontas de pulverização e inseticidas no controle de S. frugiperda no milho. O experimento foi conduzido em delineamento em blocos casualizados, em esquema fatorial 2 x 2 x 2 + 1 com quatro repetições. Os fatores foram duas taxas de aplicação (100 e 200 L ha -1 ), duas pontas de pulverização (jato plano com e sem com indução de ar) e dois inseticidas (triflumuron e fenpropatrina). Também se utilizou um tratamento controle correspondente à aplicação de clorpirifós utilizando a ponta jato plano simples na taxa de 200 L ha -1 . As características avaliadas foram espectro de gotas, deposição de calda, eficácia biológica e produtividade da cultura. A taxa de aplicação de 100 L ha -1 produziu maior deposição de calda do que a 200 L ha -1 para ambas as pontas de pulverização e não reduziu a eficácia dos inseticidas. Ambos os inseticidas tiveram eficácias semelhantes no controle da lagarta-do-cartucho aos 10 dias após a aplicação (DAA), embora a eficácia do inseticida fenpropatrina tenha sido maior do que a do triflumuron aos 3 DAA. Palavras-chave: lagarta-do-cartucho, Zea mays, ponta de pulverização, taxa de aplicação, manejo de pragas. INSECTICIDE APPLICATION TECHNOLOGY ON FALL ARMYWORM CONTROL IN CORNABSTRACT -The fall armyworm (Spodoptera frugiperda) is a key pest in corn, and insecticide applications have been needed to reduce the insect population. The fall armyworm has been difficult to control because its larvae is commonly protected in the whorl of corn, which may reduce insecticide deposition and its efficacy. Therefore, this research aimed to evaluate the effects of application rate, nozzle type and insecticide on control of S. frugiperda in corn. Experiment was conducted in a randomized complete block design and a 2 x 2 x 2 + 1 factorial scheme with four replications. The factors were two application rates (100 e 200 L ha -1 ), two hydraulic nozzles (standard and air induction flat-fan) and two insecticides (triflumuron and fenpropathrin). An additional treatment was also included, composed of chlorpyrifos sprayed at 200 L ha -1 using a standard flat-fan nozzle. Parameters of interest were droplet spectrum, spray deposition, biological efficacy and crop yield. A 100 L ha -1 application rate produced greater spray deposition than at 200 L ha -1 for both nozzle types and did not reduce the insecticide efficacy. At 10 days after application (DAA) both insecticides provided similar efficacy on fall armyworm control, although it was greater using fenpropathrin than triflumuron at 3 DAA. Keywords: fall armyworm, Zea mays, spray nozzle, spray volume, pest management. A tecnologia de aplicação, contudo...

Estudo de um sistema de eletrificação de gotas em pulverizador costal pneumático pelo método de gaiola de Faraday 1 A aplicação inadequada de agrotóxicos pode causar sérios problemas ao ambiente e o emprego de gotas com pequeno diâmetro pode favorecer a cobertura dos alvos, porém desde que ela aconteça em condições especiais para minimizar a deriva. Objetivou-se, com este trabalho, analisar os fatores que influenciam a relação carga/massa (Q/M) gerada por um sistema de eletrificação de gotas em um pulverizador pneumático costal com kit eletrostático por meio de uma gaiola de Faraday. Montaram-se dois experimentos, o primeiro em delineamento inteiramente casualizado, a fim de verificar a influência da distância entre o pulverizador e o alvo, a vazão de aplicação e a calda de pulverização, no funcionamento do sistema de eletrificação de gotas. Neste experimento, avaliaram-se quatro distâncias (0; 0,5; 1,0 e 2,0 m) entre o pulverizador e a gaiola. No segundo experimento, em esquema fatorial, analisaram-se cinco composições de caldas e cinco vazões (0,25; 0,76; 1,00; 1,45; e 1,58 L min -1 ). A relação Q/M foi determinada por meio da medição da corrente elétrica a partir do volume de calda pulverizado em gaiola de Faraday com um multímetro, dividida pela respectiva massa de líquido. Analisou-se, também, o espectro de gotas produzidas pelo pulverizador, em analisador de partículas por difração de raio laser. Verificou-se que, com o aumento da vazão de pulverização na gaiola de Faraday, menor foi a relação Q/M, o que também ocorreu com a distância do bocal do pulverizador eletrostático da entrada da gaiola. Em relação à calda de pulverização, a relação Q/M aumentou com a adição de óleo mineral, do óleo vegetal e de inseticida. Concluiu-se que a distância entre o bocal do pulverizador e o alvo, a vazão e a calda de aplicação influenciam na eficiência da pulverização eletrostática. Palavras Study of a droplet electrification system in a backpack sprayer in a Faraday cageThis study evaluated the factors affecting the charge/mass ratio (Q/M) generated by a droplet electrification system in a backpack sprayer with an electrostatic kit, using a Faraday cage. Two experiments were conducted in completely randomized design to determine the effect of application rate, the distance between the nozzle and the target, and spraying mixtures on performance of the droplet electrification system. The first study evaluated four distances (0, 0.5, 1.0, and 2.0 m) between the nozzle and the Faraday cage; the second study was conducted in a factorial design, with five tank mixtures and five flow rates (0.25, 0.76, 1.00, 1.45, and 1.58 L min -1 ). The Q/M ratio was determined using a multimeter by measuring the electric current from the volume of mixture sprayed in the Faraday cage, which was divided by the respective liquid mass. Droplet spectrum was analyzed by a particle analyzer using laser diffraction. The Q/M ratio became smaller as the spraying flow rate increased, similarly as observed with increasing distances of the electros...

Coffee plants (Coffea arabica L.) present dense foliage that obstruct the entering of pesticides inside the plant canopy uniformly. Adjust the application rate concerning the plant canopy volume can be a way to make the pesticide applications more efficient. The objective of this study was to evaluate the deposition of spray solution on coffee leaves with different volumes of plant canopy and different application rates; additionally, to determine the specific volume indexes for different coffee phenological stages. The studies of coffee leaf deposition were performed on commercial fields of C. arabica - Topázio MG 1190 and Catuaí Vermelho IAC 99 cultivars, in different months. Three volumes of vegetation ranging from 8.572 to 16.200 m3 ha-1 - obtained from the calculation of tree-row volume (TRV) performed in 20 plants - and five application rates (200, 300, 400, 600 and 800 L ha-1) and in each phenological stage (maturation, post-harvest, grain filling) were evaluated in a randomized block design with five replications. A bright blue marker was added to the spray solution to be detected by spectrophotometry in order to study the spray deposition and losses to the soil. After the treatment applications, ten coffee leaves corresponding to the 1st pair of leaf from an orthotropic branch of each third of the coffee plant (upper, middle, lower) were randomly collected. Petri dishes were used to evaluate the losses to the soil. The TRV and leaf density should be considered together in the definition of the application rate for coffee protection. It is also possible to reduce the application rate to values close to 200 L ha-1. The volume indexes for each coffee phenological stage were defined for proper canopy wetting and low losses to the soil.

Tank mixture of pesticides and foliar fertilizes for Triozoida limbata control in guava trees (Psidium guajava L.) 1Although the tank mixture of pesticides and foliar fertilizers is common practice in agriculture, further clarification and scientific support is needed to be regulated. Thus, the objective of this work was to evaluate the effect of tank mixture of an organosilicon adjuvant and manganese foliar fertilizer throw the insecticide imidacloprid effectiveness over Triozoida limbata control in guava trees. The experimental plot was considered with four trees followed in the same cultivation line subdivided into 4 quadrants. The experiment followed a randomized block design with split plots, with four replications. Treatments were T1 -Imidacloprid (Imid.); T2 -Imid. + Polyether-polymethyl siloxane copolymer (Sil.); T3 -Imid. + MnSO 4 ; T4 -Imid. + Sil. + MnSO 4 ; T5 -Control (no application). Physical-chemical characteristics, spray deposition over the leaves and losses to the soil, guava psyllid percentage of infestation and nymph's number were evaluated. The addition of foliar fertilizer on the mixture reduced the pH and surface tension and increased the electric conductivity and viscosity of the insecticide solutions. The silicon adjuvant reduced the surface tension and increased the viscosity and the pH. The tank mixture of organosilicon adjuvant and manganese foliar fertilizer do not influence the efficacy level of the insecticide.

Among the pests that attack the maize, the maize leafhopper, which causes direct damages by sap-sucking and indirect ones, stands out as being a vector of pathogens and viruses, and can cause losses of up to 100% of the production. An alternative to improve the chemical control of this pest is the use of electrostatic spraying technology. However, there is no research support. This study aimed to evaluate the deposition of spray in the maize crop and the effectiveness in the chemical control of the maize leafhopper, using the electrostatic spraying system, at different application rates, compared to the conventional spraying system. The experiment was conducted in a randomized block design with five treatments, in a 2x2 + 2 factorial scheme: presence or absence of electrostatic spraying system, two application rates (35 and 50 L ha-1), an additional treatment using a hydraulic spray nozzle and a rate of 100 L ha-1, and other additional treatment without the application of insecticide, in order to support the study of pest infestation. Each treatment consisted of eight replicates, in which the spray deposition in the maize canopy and the efficiency in the control were evaluated. For the insecticide applications, a boom sprayer with induction electrostatic spraying system was used with indirect electrification. To evaluate the deposition, the Brilliant Blue FCF marker was added to the spray to be detected by absorbance in spectrophotometry. For the biological efficacy of the maize leafhopper, the insecticide composed of thiamethoxam and lambda-cyhalothrin was used compared with the control without the application. There was a significant increase in the spray deposition, both in the upper and lower maize leaves, with the use of electrostatic spray technology compared to the conventional spray system. The control of the maize leafhopper was also superior. The electrostatic spraying also made it possible to reduce the application rate by approximately three times in relation to that used in conventional hydraulic spraying.

ABSTRACT:Nowadays, few studies have been conducted to evaluate the effect of tank mixture of pesticides on pest chemical control in maize crops, however the farmers are often using these mixtures, without any technical support. The current study focused on assessing some pesticide mixtures to control Spodoptera frugiperda with triflumuron in a conventional corn hybrid. Moreover, this experiment aimed to assess likely plant physiological effects, as well as physical-chemical characteristics of these tank mixes. To this end, four treatments were carried out in a randomized block design with five replications, being repeated in two seasons. Treatments consisted of different pesticide mixtures, such as insecticide (INS) + adjuvant (ADJ); INS + ADJ + fungicide (FUN); INS + ADJ + FUN + foliar fertilizers (FF); control (Ctrl). The treatments underwent analyses of mixture physical-chemical characteristics, sampled caterpillar number and size, leaf gas exchange (IRGA), and amount of chlorophyll a and b. Spray liquid characteristics changed with used mixture. Fertilizer addition caused major changes in spray liquid properties as increasing pH and electrical conductivity. No effect was observed by mixing azoxystrobin, cyproconazole, zinc oxide and manganese sulfate to triflumuron concerning control effectiveness of Spodoptera frugiperda in the corn plants. Conversely, each pesticide mixture had a distinct effect on plant physiological variables.

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