For an important and expensive crop such as corn, the resistance of Spodoptera frugiperda J.E. Smith to various pesticides has led to research throughout the world for a potential insecticide from a natural source. For the management of pest resistance, natural compounds associated with synthetic insecticides can be a promising tool because they can reduce the application of the synthetics molecules while maintaining their effectiveness and promoting the control of the pests. Linalool is a potential insecticide that is easily obtained because it is found in high concentrations in the essential oil of Ocimum basilicum L. Therefore, the present study aimed to evaluate the toxicity of this essential oil and its combination with deltamethrin to control S. frugiperda. Through dose response assays, the acute toxicities (LD 50 ) of the essential oil and deltamethrin were estimated. Additionally, the combination of these materials was also assessed, attaining a reduction of 80% of the LD 50 of deltamethrin while obtaining the same result as when the pyrethroid was administered alone. From these results, it is expected that the combination of natural compounds and synthetic insecticides will be a promising practice, helping to manage resistance while reducing the environmental impact of toxic compounds.Index terms: Natural insecticides; linalool; fall armyworm; pyrethroid; synergism. RESUMOPara uma cultura importante e expressiva como o milho, a resistência de Spodoptera frugiperda J.E. Smith a vários inseticidas atraiu a atenção no mundo para pesquisar o potencial inseticida de compostos naturais. Para o manejo da resistência, os compostos naturais associados a inseticidas sintéticos podem ser uma ferramenta promissória por reduzirem a aplicação das moléculas sintéticas para que não percam sua eficácia, além de promover o controle das pragas. O linalol é um terpenoide considerado como inseticida potencial, pode ser facilmente obtido naturalmente uma vez que é encontrado em alta concentração no óleo essencial de Ocimum basilicum. Portanto, o presente estudo teve como objetivo avaliar a toxicidade deste óleo essencial e sua combinação com deltametrina no controle de Spodoptera frugiperda. Através do ensaio de dose-resposta, foi estimada a toxicidade aguda (DL50) do óleo essencial e da deltametrina. Adicionalmente, foi também avaliada a combinação entre ambos, alcançando uma redução de 80% da DL 50 de deltametrina para se obter o mesmo resultado quando o piretroide foi administrado sozinho. A partir dos nossos resultados, espera-se que uma combinação de uso de compostos naturais e inseticidas sintéticos possa ser uma prática promissora, auxiliando no manejo da resistência de pragas e principalmente reduzindo os impactos ambientais de compostos tóxicos.

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.

The frequent tank mixing of phytosanitary products, adjuvants, and foliar fertilizers highlights the lack of information which sustains decisions about what products can be mixed for spray application. Thus, the aim of this study was to evaluate the physical and chemical characteristics of fungicides, herbicides, and insecticides in combination with some adjuvants on the Brazilian market. The experimental design was completely randomized and spray mixes of the phytosanitary products: fungicide (azoxystrobin+benzovindiflupir), herbicide (diamônio salt of N-(phosponomethyl)) or insecticide (fenpropathrin) were evaluated in combination with adjuvants (mineral oil base, foliar fertilizer or lecithin + propionic acid), and in two application rates (95 and 52 L ha-1); all with four replications. Surface tension, electrical conductivity, pH, dynamic viscosity and density of spray mixes were evaluated. The adjuvants presented characteristics capable of significantly altering the physicochemical properties of the phytosanitary spray mixes, and thus, alter the biological effectiveness and efficiency of the spray applications. However, its effects are also dependent on the phytosanitary product added to the spray mix, which makes general recommendations a difficult task. The greatest pH reduction, as well as the greatest increase in electrical conductivity, were caused by the adjuvant lecithin + propionic acid. All phytosanitary products and adjuvants studied, associated or not, resulted in a reduction in the surface tension of the spray mix in relation to water. The magnitude of change of density and dynamic viscosity promoted by adjuvants was lower than the other characteristics evaluated.

Sorghum is a crop already established for off season planting, in succession to soybeans in the Southeast, Midwest and also in some areas of Northeast in Brazil. Studying new cultivars is necessary for the sorghum development in the country. Therefore, this study evaluated the productive performance of sorghum in different sowing dates and determined the SPAD chlorophyll index, correlating it with macronutrient contents in hybrids in different development stages and sowing dates. Experiments were conducted in contiguous areas in four sowing dates, the first one was sown on February 26 2013 and the others at 17, 30 and 41 days after the first sowing -(DAFS). The experiments were conducted in a randomized block design with nine hybrids and four replications. Each sowing date was considered an individual experiment, and grouped analysis was done to compare characteristics. Macronutrients and indexes content data of Soil Plant Analytical Division value (SPAD) were evaluated at three different stages within the plant cycle, characterizing an experiment in split plot (development stages -subplots), with the factor in the plot (hybrid x sowing time). Pearson's correlation coefficients for the variables macronutrient and SPAD index were calculated. Production performance of sorghum hybrids varied according to sowing dates. Macronutrient content of sorghum hybrids varied in different development stages evaluated and sowing dates. SPAD chlorophyll index values have positive linear correlations with nitrogen content in the analyzed phenological stages.

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.

No abstract

Electrostatic spray can bring benefits to the pesticide application such as the reduction of application rate and the increase of deposits on targets. Therefore, this study aimed to evaluate the effect of electrostatic spraying using lower application rates and different adjuvants on soybean spray deposition and chemical control of powdery mildew (Microsphaera diffusa Cooke & Peck). The field experiment was conducted in duplicate. A randomized complete block design with four replications in a 2 × 2 × 2 + 1 factorial scheme was used. The factors were two application rates, with and without droplet electrification, two spray solution compositions, and one additional treatment. Deposition on upper and lower leaves, spray loss to the soil, and powdery mildew control effectiveness were evaluated. The electrical conductivity of the spray solution and the charge/mass ratio induced in droplets were also evaluated. All treatments reduced the soybean powdery mildew severity. Electrostatic spraying responded positively to an increase in the electrical conductivity of the spray solution regarding the charge/mass ratio, but it did not increase spray deposition on the lower third of the canopy and did not influence spray loss to the soil, which was higher as the application rate increased.

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.