Heterogeneidade da relação entre produtividade da soja e severidade da ferrugem asiática: uma análise exploratória.

This work aimed to conduct an exploratory, prior to meta-analysis, assessment of the heterogeneity of the linear relationship between soybean yield (Y) and the severity (X) of a foliar fungal disease (soybean rust) from 144 fungicide trials conducted in five years and 45 locations in Brazil. We used graphical analysis to explore the within- and between-trial variability of model parameter estimates (effect sizes) and summary measures for model goodness-of-fit and influence analysis. In the estimation of the weighted mean regression coefficients, following the metaanalysis concept, we propose a method that takes into account the magnitude of influence measures as well as the uncertainties of parameters estimates, usually the inverse of the standard error of for the parameter estimate. High between-trial heterogeneity was observed for parameter estimates, standard errors (within trial variability), determination coefficient and influence measures. Graphical analysis suggested influence of timing of disease onset and control yield class on model slope, which will be quantified further using a meta-analytical approach

Métodos probabilísticos para quantificar a influência do El Niño/oscilação sul sobre o risco de epidemias.

Neste trabalho, apresentamos e discutimos as vantagens e limitações de métodos estatísticos paramétricos e semi-paramétricos para a caracterização da influência do fenômeno El Nino/Oscilação Sul (ENOS) sobre o risco de epidemias de doenças de plantas. Foram utilizados dados simulados de um índice de severidade da ferrugem asiática em soja para Rosário do Sul, RS, local previamente identificado como passível da influência de ENOS na precipitação pluvial no período da safra. A influência ENOS sobre a produtividade agrícola e outras variáveis dependentes da precipitação pluviométrica, como a severidade de doenças, é bem conhecida e documentada em todo o mundo. No entanto, o uso rigoroso de abordagens probabilísticas inferenciais para quantificação da influência de indicadores climáticos sobre o de risco de epidemias ainda é raro

Eficiência do controle da ferrugem asiática da soja em função do momento de aplicação sob condições de epidemia em Londrina, PR.

Com o objetivo de estudar a eficiência do controle da ferrugem asiática da soja em função do momento de aplicação foram conduzidos ensaios em Londrina, PR, Brasil, durante as safras 2005/06 e 2006/07. A mistura de 60 g azoxistrobina há + 24 g ciproconazol há foi aplicada em diferentes estádios fenológicos, iniciando em R2 até R5.5, em aplicações únicas e seqüenciais. A severidade foi estimada periodicamente para o cálculo da área abaixo da curva de progresso da doença (AACPD) e a produtividade avaliada no final do ciclo. Nas duas safras, os sintomas iniciais foram observados no final do estádio vegetativo. Na safra 2005/06, o tratamento com aplicações seqüenciais, em R2 e R5.1, foi o mais eficiente na redução da severidade e da AACPD e apresentou a maior produtividade. Na safra 2006/07, os tratamentos com aplicações seqüenciais, em R2 e R5.1, e a aplicação única em R3 apresentaram as menores severidades, menores AACPD e maiores produtividades. Correlações negativas foram encontradas entre as variáveis severidade em R6 e AACPD e a produtividade (-0,83 e -0,84 em 2005/06 e -0,87 e -0,89 em 2006/07). As aplicações realizadas com níveis elevados de severidade, ao redor de 50%, apresentaram produtividade igual à testemunha não tratada

Meta-analysis of the linear relationship between soybean yield loss and rust severity from uniform fungicide trials.

To quantify yield loss in soybean as affected by rust severity, meta-analysis was used to examine data from uniform fungicide trials (UFTs) conducted across 25 locations and 5 years (2003?2008) in the main soybean production regions of Brazil. Trials (n = 81) were selected based on predefined criteria and examined for the linear relationships between soybean yield loss (%) and rust severity (%) at the R6 growth stage. Slopes of the yield loss × severity relationship were estimated by linear regression. The influence of potential moderator variables on slopes was examined by a random effects model. Forty-one trials were excluded due to the presence of influential observations in the negative linear relationship between yield and severity. There was considerable variation among slope estimates for the increase in yield loss with respect to the change in soybean rust severity (0.31?1.81 p.p./p.p.). A significant and positive relationship between soybean rust severity and yield loss was found. For every increase of 1 p.p. in soybean rust severity, the average increase in yield loss was 0.71 p.p. (95% CI = 0.60?0.82 p.p.). The moderator variable timing of disease onset and severity class accounted for 17 and 16% of the overall and between-trial variability of slopes, respectively. This study provides an approach for quantitative risk assessments of rust-related soybean yield loss, an important step for an economic evaluation of alternative rust management strategies.Edição do Proceedings of the National Soybean Rust Symposium, New Orleans, 2009

Construindo a necessária capacidade de lidar com as mudanças climáticas globais e respectivos impactos em agricultura e na alimentação.

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Genome Sequence of Fusarium graminearum strain CML3066 isolated from a wheat spike in Southern Brazil

Fusarium graminearum is a global fungal pathogen of wheat and other small grains, causing Fusarium Head Blight (FHB) disease, also known as wheat scab. We report herein the annotated genome of a deoxynivalenol/15-acetyl-deoxynivalenol-producing Brazilian strain called CML3006, isolated from FHB-symptomatic wheat spikes collected in 2009

Development of Glomerella leaf spot is enhanced in virus-infected Maxi Gala apples.

Apples are commercially grown in Brazil in a subtropical environment that favors the development of fungal diseases such as Glomerella leaf spot (GLS) caused mainly by Glomerella cingulata (anamorph Colletotrichum gloeosporioides). The main objective of this work was to evaluate the effect of mixed infections by Apple stem grooving virus (ASGV) and Apple stem pitting virus (ASPV) on the infection and the colonization processes of C. gloeosporiodes in cv. Maxi Gala plants. Leaves of 16-month-old potted plants were spray-inoculated and both the disease incidence and lesion count were monitored over time and leaf severity was assessed in the final evaluation using an image analysis tool. Results showed that initial infection estimated from a monomolecular model fitted to progress of lesion count was higher and the incubation period (time to reach 50% incidence) was on average 10 h shorter in virus-infected plants compared to non-infected plants. It is hypothesized that initial events such as conidial germination and fungal penetration into plant cells were facilitated by the presence of viral infection. Also, final GLS severity was significantly higher in the virus-infected plants. Mixed infections by ASGV/ASPV seemed to make apple leaves more susceptible to the initial infection and colonization by C. gloeosporioides

Genetic population structure and trichothecene genotypes of Fusarium graminearum isolated from wheat in southern Brazil

A sample of 140 Fusarium graminearum isolates from Rio Grande do Sul, Brazil, representing three populations at least 150km from one another, were examined for trichothecene genotype based on PCR amplification of portions of the Tri3 and Tri12 genes and a species-specific (Fg16F/R) primer pair. Genetic diversity was assessed in a sample of 103 F. graminearum lineage 7 (F. graminearum sensu stricto) isolates using amplified fragment length polymorphism (AFLP) markers. The 15-ADON genotype was dominant, followed by the NIV genotype (2-18% prevalence), across all three populations. All NIV-type isolates were in lineage 2 (F. meridionale) and all 15-ADON-type isolates were in lineage 7. Isolates with the same haplotype were rare and genotypic diversity was uniformly high (≥98% of the count), suggesting that recombination has played a significant role. The number of migrants (N m) was estimated between 5 and 6 across all loci and all populations, but the high frequency of private alleles (up to 30%) suggests a historical, rather than contemporary, gene flow. Regarding linkage disequilibrium, 0·8, 1·5 and 2·2% of the locus pairs from the three populations were in disequilibrium, which is lower than values reported in other locations. Thus, Brazilian populations differ from those found in Europe, North America and most of Asia in the presence of a significant frequency (7·8%) of isolates of the NIV genotype in lineage 2. © 2011 The Authors. Plant Pathology © 2011 BSPP.Fil: Astolfi, P.. Universidade Federal do Rio Grande do Sul; BrasilFil: Reynoso, Maria Marta. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigación en Micología y Micotoxicología. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación en Micología y Micotoxicología; ArgentinaFil: Ramirez, Maria Laura. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigación en Micología y Micotoxicología. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación en Micología y Micotoxicología; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología; ArgentinaFil: Chulze, Sofia Noemi. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigación en Micología y Micotoxicología. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación en Micología y Micotoxicología; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología; ArgentinaFil: Alves, T. C. A.. Universidade Estadual de Maringá; BrasilFil: Tessmann, D. J.. Universidade Estadual de Maringá; BrasilFil: Del Ponte, E. M.. Universidade Federal do Rio Grande do Sul; Brasi

Indicações técnicas para minimizar a contaminação de trigo por micotoxinas.

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