Glauber Renato Stürmer

Populações de plantas e estratégias de manejo de irrigação na cultura da soja

Este trabalho teve por objetivo verificar o efeito do manejo da irrigacao e da populacao de plantas sobre o rendimento de graos em soja semeada apos a epoca recomenda. O experimento foi conduzido de janeiro a maio de 2005 na Universidade Federal de Santa Maria. O delineamento experimental utilizado foi blocos ao acaso com parcelas subdivididas e quatro repeticoes. Nas parcelas principais foram distribuidos tres manejos de irrigacao: 1) nao-irrigado; 2) irrigado todo o ciclo; e 3) irrigado nos periodos criticos. Nas subparcelas foram distribuidas duas populacoes de plantas (250.000 e 400.000 plantas ha-1). Para as plantas irrigadas todo o ciclo ou somente nos periodos criticos, o rendimento de graos nao diferiu entre as populacoes testadas. O rendimento de graos das plantas nao-irrigadas teve um incremento de 21% com o aumento da populacao de plantas para 400.000 plantas ha-1.

Eficiência de métodos de amostragem de lagartas e de percevejos na cultura de soja

The aim of this study was to compare the collect capacity of three sampling methods for caterpillars and stink bugs in soybean. Therefore, in a 6.16ha soybean field, a grid of 154 sampling points spaced 20×20m was marked. In each of these 154 points were collected caterpillars (small, large and total) and stink bugs (nymphs, adults and total) (six variables) by the sampling methods beating cloth, wide beating cloth and vertical beat sheet, on 14 phenological stages of the soybean crop, totaling 6,468 samples. For each of these six variables, on each of the 14 phenological stages and overall (all phenological stages), the averages of the three sampling methods were compared by Students t test (bilateral) for paired data, in a 5% probability level. The number of caterpillars collected by the sampling methods decreases in the following order: vertical beat sheet, wide beating cloth and beating cloth. The number of stink bugs collected by the sampling methods vertical beat sheet and wide beating cloth is higher than beating cloth. Vertical beat sheet is the most efficient to collect caterpillars and stink bugs.

Sistemas de aplicação e inseticidas no controle de Anticarsia gemmatalis na soja

A B ST R A C T The application of insecticides to control Anticarsia gemmatalis in soybean is through hydraulic nozzles. Among the innovations stands out the air-assisted boom sprayer and the application of low oil volume by a rotary discs atomizer. In an experiment conducted with soybean during the 2009/2010 growing season, the control efficiency of A. gemmatalis using application systems and insecticides was assessed. The experimental design was a two-factor, with the factor A being the application systems, as follows: A1 - spraying with rotary discs atomizer; A2 – spraying with hydraulic nozzles and A3 – spraying with airassistance; and factor D was composed of insecticides, as follows: D1 - Cypermethrin and D2 - Lufenuron + Profenofos. There was no interaction between insecticide and application systems and the insecticide Lufenuron + Profenofos presented a superior residual effect than Cypermethrin. The low oil volume spray system with rotary discs atomizer and system hydraulic nozzles with air-assisted boom sprayer are more efficient than hydraulic nozzles to control Anticarsia gemmatalis in soybean.

Application methods and insecticides for controlling stink bugs in soybean

Insecticides application is the most widely used form to control stink bugs in soybean, being the application technology and the insecticide used the major factors for an efficient control. The experiment was conducted in a soybean field during the 2008/09 growing season, in São Sepé, RS, in order to evaluate efficiency of three methods of application and two insecticides for controlling stink bugs in soybeans. The experimental design used was completely randomized, in a factorial scheme 3x2 +1 control, with five replicates. The experimental units had dimensions of 40.0 x 40.0 m. The factor A was represented by the methods of application, as follows: A1Tractorized spray with hydraulic nozzle; A2Aerial, with rotary disc atomizers and A3Aerial, with hydraulic nozzles. The factor B was represented by the insecticides, as follows: B1thiamethoxam + lambda-cyhalothrin and B2-acephate. Ground and aerial applications with low volume oily had greater efficiency for controlling stink bugs in soybean, where led to an increase in soybean grain yield. Insecticides thiamethoxam + lambda-cyhalothrin and acephate were similar in controlling stink bugs and in residual effect.

Sample size for estimating the population of stink bugs in soybean crops

It is important to quantify the population of stink bugs in the soybean, in order to determine the actions which are necessary for their control to protect the crop from losses in production, together with a reduction in cost and less environmental impact. The objectives of this study were to determine the sample size (the number of sampling points) needed to estimate the average population density of the bugs, and to verify the variability in sample size for the phases and species of the bugs and the phenological stages of the plants. In an area of 6.16 ha of soybeans, a grid of 154 sampling points, spaced 20 × 20 m apart, was laid out. Population-density data were collected for nymphs and adults of the species Dichelops furcatus (Fabricius, 1775), Piezodorus guildinii (Westwood, 1873), Edessa meditabunda (Fabricius, 1794), Nezara viridula (Linnaeus, 1758), Euschistus heros (Fabricius, 1794) and Chinavia sp. (Say, 1832) employing a vertical beat sheet at 14 different phenological stages. Measurements of central tendency and variability, the Morisita index and the k parameter of negative binomial distribution were all calculated. Homogeneity of variances was verified and the sample size calculated. There is variability in the sample size when estimating the average population density of bugs across the phases and species of bug and the phenological stages of the soybean. Smaller sample sizes are necessary for the nymphs of P. guildinii and the final phenological stages (R6, R7.1, R7.3 and R8.2). Thirty-six sampling sites are enough to estimate the average population density of bugs in the final phenological stages (R6, R7.1, R7 .3 and R8.2) at an error of estimation equal to 30% of the estimated mean and at a level of confidence of 95%.

Dimensionamento de amostra na estimação da população de corós em áreas de campo nativo e de cultivo no Estado do Rio Grande do Sul

E importante quantificar a densidade populacional de coros para definir o momento adequado para o controle da praga. Assim, o objetivo deste trabalho foi determinar o tamanho de amostra (numero de trincheiras por hectare) para a estimacao da media de densidade populacional de coros em areas de campo nativo e de cultivo em diferentes locais do Estado do Rio Grande do Sul. Foram coletados dados de densidade populacional de coros, independentemente de especie, em areas de campo nativo e de cultivo em 17 locais, por meio de contagens realizadas em trincheiras de 20cm x 50cm com 30cm de profundidade. Em cada uma das 34 areas amostradas, calcularam-se medidas de tendencia central, de variabilidade, de assimetria e de curtose, e testou-se a normalidade dos dados. Em seguida, verificou-se a homogeneidade de variâncias entre as areas em cada local e entre os locais em cada area. Depois, calculou-se o tamanho de amostra em cada area e local. O tamanho de amostra (numero de trincheiras por hectare) para a estimacao da media de densidade populacional de coros e dependente da area (campo nativo ou de cultivo) e do local. Para as areas e os locais estudados, 61 trincheiras por hectare sao suficientes para estimar a media de densidade populacional de coros, para um erro de estimacao igual a 30% da media estimada, com grau de confianca de 95%.