An apparent decline of fungicide performance for the control of soybean rust in Brazil has been reported but the rate at which it has occurred has not been formally quantified. Control efficacy and yield response to three fungicides applied as single active ingredients (a.i.)—azoxystrobin (AZOX), cyproconazole (CYPR), and tebuconazole (TEBU)—and four applied as mixtures—AZOX+CYPR, picoxystrobin + CYPR, pyraclostrobin + epoxiconazole, and trifloxystrobin + prothioconazole (TRIF+PROT)—were summarized using network meta-analytic models fitted to mean severity and yield data from 250 trials (10-year period). The effect of year was tested on both variables in a meta-regression model. Overall control efficacy ranged from 56 to 84%; the three single-a.i. fungicides performed the poorest (56 to 62%). Yield increase for single-a.i. fungicides was as low as 30% but ranged from 47 to 65% for the premixes. Significant declines in both variables were detected for all fungicides except TRIF+PROT. For TEBU, control efficacy (yield response) declined the most: 78% (18%) to 54% (8%) from 2004–05 to 2013–14. The recent surge of resistant populations of Phakopsora pachyrhizi to both demethylation inhibitor and quinone outside inhibitor fungicides is likely the driving force behind a significant decline after 4 years of fungicide use.

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Resumo -O objetivo deste trabalho foi avaliar a eficiência dos métodos de detecção de Sclerotinia sclerotiorum em sementes de soja. Foram realizados experimentos durante três safras, tendo-se utilizado amostras de sementes de soja contaminadas artificial e naturalmente, com incidência conhecida da doença nas amostras e no campo. Os métodos de incubação utilizados foram: papel de filtro, rolo de papel e meio Neon-S. Observou-se aumento da detecção do patógeno nas sementes infectadas artificialmente, à proporção que aumentou a incidência na amostra. Os métodos podem não detectar o patógeno S. sclerotiorum em sementes de soja naturalmente contaminadas. Os níveis de incidência do patógeno em sementes de soja interferem na sensibilidade dos métodos de detecção, e não há relação entre a incidência no campo e na semente colhida.Termos para indexação: meio Neon-S, método do papel de filtro, método do rolo de papel, mofo-branco. Incidence of Sclerotinia sclerotiorum on soybean seeds and sensitivity of detection testsAbstract -The objective of this work was to evaluate the efficiency of detection methods of Sclerotinia sclerotiorum on soybean seeds. Experiments were carried out during three crop years, using samples of soybean seeds artificially and naturally contaminated, with known pathogen incidence on samples and on the field. The incubation methods used were: filter paper, paper roll, and Neon-S medium. An increase in pathogen detection on artificially contaminated seeds was observed, as the incidence in the sample increased. The methods may not detect the pathogen S. sclerotiorum on naturally contaminated soybean seeds. The levels of pathogen incidence on soybean seeds interfere in the sensitivity of the detection methods, and there is no relationship between the incidence on the field and on the harvested seed.

This work had as objectives the study of the physical and mechanical characteristics of maize kernels in relation to

BACKGROUND: Soybean seed treatment with fungicides is a well-established disease management strategy. However, the movement of these fungicides within seedlings is not always well characterized. Thus, the objectives of this study were to determine the pattern of translocation of three fungicides with different modes of action applied as a seed treatment, and the effect of soil type on translocation.RESULTS: Most of the absorbed radioactivity was concentrated in the cotyledons and the maximum sum of the rates of absorption by roots, stems, and leaves of the plants was 15%. In most cases, absorption by roots, stems, and leaves were lower than 5% for 14 C-pyraclostrobin and 14 C-metalaxyl, and 1.6% for 14 C-carbendazim. Fungicides absorbed by the roots and the whole seedlings were higher when plants were grown in soil with lower organic matter content. Fungicides in the cotyledons are unlikely to be redistributed and are lost when cotyledons fall off the plants.CONCLUSION: Cotyledons are the part of the plant where fungicides are most absorbed, regardless of the fungicide. Soil type affects the absorption of fungicides, and in this study it was most likely caused by soil organic matter. These data improve knowledge of the movement of seed treatment fungicides in soybean seedlings and may help the development of seed treatment chemistry to manage seed and soilborne pathogens.

Sclerotinia sclerotiorum is one of the most devastating and cosmopolitan plant pathogens. Rapid detection of S. sclerotiorum can provide growers an advantage in knowing what control measures should be taken to minimize crop damage and financial losses caused by it. Loop-mediated isothermal amplification (LAMP) is a fast, sensitive, and specific nucleic acid amplification method that does not require a thermal cycler. This study aimed to develop a LAMP-based assay for the specific detection of S. sclerotiorum (Ss-LAMP). A real-time quantitative LAMP reaction (Ss-qLAMP) and a calcein ion indicator-based LAMP reaction (Ss-cLAMP) were designed, optimized, and tested on fungi, plant, and soil samples. The Ss-LAMP reactions were very specific and sensitive. Applying the artificially inoculated soil samples with DNA purified by five protocols in the Ss-qLAMP reaction, it was possible to detect and quantify the pathogen DNA, regardless of the extraction protocol. Naturally infected soybean tissues had the pathogen detected by Ss-cLAMP directly in the reaction tube with no DNA extraction requirement. The assays should be applicable for many types of samples, such as soil, spore traps, and plant tissues from several crops, with no requirement for DNA extraction. The Ss-LAMP reactions took less than 1 h to complete, and they can be made directly in the field with real-time quantitative results (Ss-qLAMP) or qualitative naked-eye visual results (Ss-cLAMP). Results were obtained with 10 pg of DNA or 10 ng of crude mycelium, suggesting a detection limit close to a single DNA copy. Ss-LAMP reactions will allow rapid and accurate diagnosis of S. sclerotiorum and assist in pathogen management and control.

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Conclui-se ainda, que os níveis de contaminação por zearalenona foram altos, quando comparados às legislações de alguns países. A implementação de leis que especifiquem a contaminação máxima por zearalenona em grãos para consumo é de grande importância, evitandose assim grãos excessivamente contaminados, o que pode prejudicar a saúde humana.