Ivan Francisco Dressler da Costa

Elaboração e validação de escala diagramática para quantificação da mancha de isariopsis da videira

The lack of a standardized visual method may lead to inaccurate severity estimative and wrong conclusions. The objective of this research was to develop a diagrammatic scale to assess the severity of grape isariopsis leaf spot on grape, caused by Isariopsis clavispora. A diagrammatic scale with six levels of disease severity (1.60; 3.20; 6.60; 13.00; 24.10 e 40.24%) was developed and validated to assess grape isariopsis leaf spot. For validation, the severity of 30 leaves presenting different intensities of the disease was estimated by eight raters. Accuracy and precision were determined by linear regression and by the actual severity scale. This one provided good levels of accuracy and accuracy of visual estimation. The coefficient determination average was higher than 0.89, and absolute errors were lower than acceptable limits. The levels of accuracy, precision and reproducibility measurements of isariopsis leaf spot severity on grape significantly improved with the use of diagrammatic scale. The proposed diagrammatic scale proved to be adequate for severity assessments of grape isariopsis leaf spot.

Aplicação aérea de fungicidas na cultura do arroz irrigado com diferentes bicos de pulverização

In the harvest year of 2007/2008 a study was carried to evaluate the droplets deposition and penetration throughout water sensible cards and gas chromatographic analysis. Were used the hydraulic nozzle, electrostatic nozzle and rotary-disk atomizer spraying systems, with different volumes of spray solution. Aerial applications were performed at R3 stage using the aircraft Ipanema EMB-202 and the fungicide trifloxystrobin + propiconazole. Throughout the lection of the water sensible cards was determinate the droplet density, the medium numeric diameter, the medium volumetric diameter, the relative amplitude and the percentage of droplet penetration in the canopy. Chromatographic analysis was also performed to determinate the fungicide penetration into the biological target. The pulverization systems hydraulic nozzle 20L ha-1 and 30L ha-1 and the electrostatic system 10L ha-1 demonstrated higher droplet density in the upper third. The rotary-disk atomizer 15L ha-1 showed higher droplet density in the mid and low third. To the medium volumetric diameter, the electrostatic nozzles and the rotary-disk atomizer showed the lowest values. The higher homogeneity in the upper third was attained with rotary-disk atomizer at the pulverization rates of 6L ha-1 and 10L ha-1. The chromatographic analysis showed that the higher quantity of product retention was obtained with the electrostatic system at the pulverization rate of 10L ha-1 in the lower plant extract.

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.

Ocorrência de Phakopsora euvitis Ono em Santa Maria, Rio Grande do Sul

In 2004/05 seanon the grape rust was identified by the first time attacking vineyard located in the Santa Maria/RS region. In Brazil it had already been identified in Jandaia do Sul/PR (2001), Sao Paulo and Mato Grosso do Sul (2003). The disease is caused by Phakopsora euvitis. The fungi is easily disseminated by wind and favored by high temperature and umidity. Such conditions are normally observed in Santa Maria region what make possible the fungus to survive on alternative host or migrate from other regions.

Severidade de doenças e manutenção da área foliar verde em função da aplicação de micronutrientes e fungicidas em trigo

In the crop cycle of 2007, an experiment was carried out in order to evaluate the influence of zinc, manganese and molybdenum sprayed together with fungicides on the severity of diseases and leaf area maintenance in wheat. Fungicides were sprayed at the end of booting and during flowering, whereas micronutrients were only sprayed during flowering. Micronutrients levels in the leaves, severity of diseases caused by Drechslera tritici and Septoria tritici, SPAD (Soil Plant Analysis Development) index, hectoliter weight, thousand-grain weight, ear size, and grain yield were evaluated. The use of epoxiconazol + pyraclostrobin led to a better control of Drechslera tritici and Septoria tritici. Products containing epoxiconazol + pyraclostrobin had an effect on plant physiology by increasing the levels of micronutrients in tissues and prolonging the time during which wheat remained with photosynthetically active leaf area. Epoxiconazol + pyraclostrobin, pyraclostrobin and epoxiconazol sprayed in association or not with micronutrients, led to increased hectoliter weight, thousand-grain weight and grain yield relative to control.

Efeito de óleo essencial de laranja associados a fungicidas no controle de doenças foliares do trigo

Foi conduzido um experimento em campo na safra de 2012 com o objetivo de avaliar a contribuicao do oleo essencial de laranja na performance dos fungicidas visando o controle de doencas foliares do trigo. O delineamento experimental foi o de blocos ao acaso em arranjo fatorial (3x5) + 1, com quatro repeticoes. O fator A foi composto pelos fungicidas (dose do produto comercial) epoxiconazol (0,75L ha-1), piraclostrobina (0,80L ha-1) e epoxiconazol+piraclostrobina (0,75L ha-1) e o fator B pelos adjuvantes (doses) oleo mineral (500mL ha-1) e oleo essencial de laranja (0, 50, 100 e 150mL ha-1). O tratamento adicional compreendeu-se pela testemunha (agua). O controle de manchas foliares na folha bandeira foi mais eficaz com a aplicacao de epoxiconazol e de epoxiconazol+piraclostrobina independentemente do adjuvante usado ser oleo mineral ou oleo essencial de laranja, enquanto que os adjuvantes testados nao interferiram no controle da ferrugem. O peso do hectolitro, massa de mil graos e a produtividade do trigo nao foram afetados negativamente pelas diferentes concentracoes do oleo essencial de laranja.

TAMANHO DE AMOSTRA PARA AVALIAR A SEVERIDADE DE BRUSONE DA FOLHA EM EXPERIMENTOS COM ARROZ IRRIGADO

The aim of this study was to determine the sample size needed to assess the severity of leaf blast in rice in experiments with different fungicide treatments. The severity and the area under the disease progress curve data of three chemical disease control treatments carried out in Rio Grande do Sul, were used in the study. Analysis of variance was performed to verify whether the severity of the disease differed between treatments. The spread of disease was was also found to be different between treatments and assessments, using the variance/mean ratio and Morisita index. The spatial distribution of the disease among the treatments and during the evaluations is important for the choice of the equation used to calculate the sample size. The spatial distribution of the disease was not the same across the experiments, and it varied between treatments and evaluations. Thus, we decided to use a formula that was not associated with distributions to indicate the spatial distribution (negative binomial or Poisson) of the disease in the field. The sample size to estimate the average of rice leaf blast severity varied between treatments and evaluations. The area under the disease progress curve is necessary to be determined to reduce the number of samples needed. Thus, it is recommended to assess 293 sheets to estimate severity, and 63 to estimate AUDPC at 20% error.

Caracterização da pulverização de fungicida na cultura do trigo com pontas hidráulicas e atomizadores rotativos de discos

The study aimed to evaluate the pulverization characteristics of the hydraulic nozzles and rotary-disk atomizer with different spraying rates on wheat crops, and their operational capacity. For this reason were installed two experiments, on the harvest years of 2009 and 2010. In first year was used the cultivar Fundacep 30, and in the second year the cultivars Pampeano and Nova Era. The experiments evaluating the pulverization with flat nozzles and hollow cone spray nozzle, both with the pulverization rate of 120 L ha-1, and rotary-disk atomizer with 24 and 34 L ha-1 in low volume in oil. The evaluated parameters were the droplet density and the medium volumetric diameter on the upper, mid and lower third throughout the analysis of water sensible cards. Also, was calculated the operational capacity of the traits. The results showed that the rotary-disk atomizer with 24L ha-¹ showed a higher droplet density on the upper third, however, there was no difference among the mid and lower thirds treatments. The rotary-disk atomizer presented droplets of smaller medium volumetric diameter compared to the hydraulic nozzles that presented high droplet heterogeneity. The higher operational capacity was achieved with the atomizers, due the lower spray volume used by this equipment.

Tilletia barclayana: biologia e manejo em arroz irrigado

The rice kernel smut (Tilletia barclayana), which is considered as a secondary disease, lately has been growing in importance due to its high infestation levels and effects in seed yield. This disease is favored by elevated air temperatures and humidity; high nitrogen fertilizer rates a late sowing. In order to control it, the use or resistant varieties, appropriate sowing dates and balanced fertilization of the soil, are recommended practices.

Eficiência do óxido de fenbutatin sobre formas móveis do ácaro vermelho europeu (Panonychus ulmi Koch.) em macieira

The objective of this experiment was to evaluate the efficience of Fenbutatin Oxide for controlling mobile forms of red mite ( Panonichus ulmi Koch.). An experiment was conducted in apple orchard cv. Fuji, in Lagoa Vermelha county, RS, Brazil, in 1993/94. The results indicated that all treatments with Fenbutatin Oxide were efficients at 30 days after application.