Escala diagramática para avaliação de severidade de mancha-parda em arroz Diagrammatic scale for assessment of rice brown spot severity RESUMO Uma escala diagramática com seis níveis: 1,6; 3,2; 6,4; 12,6; 23

IElaboração e validação de escala diagramática para quantificação da mancha de isariopsis da videira (1,60; 3,20; 6,60; 13,00; 24,10 e 40,24%) (1.60; 3.20; 6.60; 13.00; 24.10

O controle eficiente de doenças na cultura do arroz irrigado depende da seleção correta do equipamento, da taxa de aplicação e da indicação certa do produto químico. O objetivo deste trabalho foi verificar a deposição de gotas na cultura do arroz comparando-se bicos hidráulicos no sistema convencional, eletrostático e atomizador rotativo de disco, em diferentes taxas de aplicação por via aérea; para tanto, foram estudadas a densidade e a penetração de gotas nos estratos médio e inferior, produtividade e rendimento de engenho do arroz. Os tratamentos avaliados foram: bico hidráulico 20 e 30 L ha-1, eletrostático 5 e 10 L ha-1 e atomizador rotativo de disco 6, 10 e 15 L ha-1. Não foram verificadas diferenças de produtividade e os equipamentos bico hidráulico 20 L ha-1 e atomizador rotativo de disco 15 L ha-1 proporcionaram maior rendimento de engenho. Maiores taxas de aplicação usando-se bicos hidráulicos e atomizador rotativo proporcionaram maior penetração e, consequentemente, também maior densidade de gotas nos dois estratos avaliados.

RESUMO O objetivo do presente trabalho foi avaliar o efeito de espectros de gotas (grossas, médias e finas) na velocidade de absorção de fungicidas, para trifólios de diferentes idades através de medida indireta expressa pelo residual de controle de ferrugem asiática da soja (Phakopsora pachyrhizi INTRODUÇÃOA ferrugem asiática, causada pelo fungo Phakopsora pachyrhizi Sidow, constitui-se na principal doença da cultura da soja, já que as condições climáticas são favoráveis ao patógeno. Na maioria das regiões, sua alta virulência e velocidade de dispersão são fatores que tornam essa doença altamente agressiva (DEBONA et al., 2008). No que tange aos tecidos das plantas, sabe-se que, com o desenvolvimento da parte aérea, ao mesmo tempo, são

Environmental factors affect the performance of fungicides in soybean (Glycine max (L.) Merr.). They also influence the residual activity of the products applied to the leaves. The objective of this study was to assess the control effectiveness of the interaction between fungicide application and rainfall simulation on Asian Soybean Rust (ASR). Two experiments were conducted, one in the greenhouse, in a completely randomized design, and the other in the field, in a randomized block design. Both the experiments had the same factorial arrangement of 6x5, with four replications. Factor A: Five fungicide applications time at 0400 h, 0900 h, 1400 h, 1800 h, 2300 h and, a control with no application; Factor B: four intervals of time between the application of fungicide and rainfall simulation at 0, 30, 60 and 120 min for the experiment in the greenhouse and at 2, 30, 60, 120 min for the experiment in the field. A control was included for both the experiments with no rainfall. The number of days to the appearance of the first pustules was determined, along with severity of ASR, relative chlorophyll index and productivity. It was found that the ASR control effectiveness of fungicide applications in soybean plants in sunlight was less efficient with rainfall simulation. The rainfall simulation had greater negative effect on disease control effectiveness in applications conducted at night under dew conditions. The application conducted at 0900 h showed the greatest disease control effectiveness in both greenhouse and in the field conditions. The 1400 h application showed decreased fungicide control residual and ASR control effectiveness, possibly due to a combination of the low relative humidity and high temperature. Rainfall simulation carried out at 120 min after application still had the ability to affect the ASR control effectiveness. Key words: Chemical control. Dew. Glycine max L. Night application. Phakopsora pachyrhizi. ResumoOs fatores ambientais afetam o comportamento dos fungicidas em soja (Glycine max (L.) Merr.). Eles também influenciam a atividade residual de produtos aplicados na folha. O objetivo do estudo

No abstract

The main goal of this study was to analyze the range of effects of nitrogen doses on Asian soybean rust (Phakopsora pachyrhizi Sydow) progress over two soybean (Glycine max Merril) cultivars. Two experiments were carried out in greenhouse and in the field, during the 2011/12 and 2012/13 crop years. In the greenhouse, plants were grown in sand in 2011/12 and in a mix of sand and soil in 2012/2013, and supplied with five N doses by dripping fertigation. In the field, the crop was fertilized with six nitrogen doses with broadcast applications. The pathogen was inoculated in all experiments. It was assessed the Area Under Rust Progress Curve (AURPC), defoliation, dry matter, total concentration of N in leaves, number of grains per plant, thousand grain weight and yield. In the greenhouse experiment, nitrogen rates increased the plant growth and the disease progress during the first year. In 2011/12 field assay, a slight decrease of rust progress and a slight increase in yield from 160 to 242 kg ha -1 were recorded. However, under favorable environmental conditions for Asian soybean rust, the increases in grain yield obtained by using high N rates on both cultivars were minor than the damage caused by the disease.

Mycotoxins occurrence in wheat grains impose risks to human and animal health. The southern Brazil has favorable weather conditions for Fusarium graminearum infections and consequently for mycotoxins accumulation on grains. The goal of this study was to evaluate the behavior of new wheat commercial genotypes to Fusarium Head Blight (FHB), to control performance of new fungicide formulations and their relationship with mycotoxins concentration in grains. The manly mycotoxin occurrence on wheat grains in southern Brazil was deoxynivalenol (DON). Two cultivars showed high DON concentration above the tolerance limits (>3000 μg kg). Many other mycotoxins monitored presented concentrations below method detection limit. Satisfactory levels of fungicide effectiveness were achieved against F. graminearum. Some fungicides promoted a satisfactory decrease on DON accumulation in grains. The best results were obtained when prothioconazole was present. SDHI (Succinate dehydrogenase inhibitors) + QoI (Quinone outside inhibitors) fungicides showed benefic effects at FHB control at field, but it did not promote satisfactory reduction on DON contamination. Fungicides can be used satisfactory for FHB control and reduce DON contamination in grains in southern Brazil. The presence of prothioconazole should be recommended. Some genotypes showed high DON concentration and it was not directly related with FHB severity at field.