A Model‐based Assessment of the Impacts of Climate Variability on Fusarium Head Blight Seasonal Risk in Southern Brazil

Abstract

The frequency of Fusarium head blight (FHB) outbreaks increased considerably in many countries in the last two decades. We used a crop-disease model to assess the impacts of climate variability over a 50-year period at Passo Fundo, Rio Grande do Sul, Brazil. Thirty individual simulation runs of a wheat model were performed for each year by varying planting dates from 1 June to 30 June. For each simulation, an FHB risk index was estimated with the disease model using the heading date simulated by the crop model. A seasonal FHB risk index was estimated by averaging the 30 indices each year. Our simulation results showed that climate at Passo Fundo became favourable to FHB after the 1980s following a period of less favourable conditions for epidemics in the 1960s and 1970s. The risk for FHB was higher for the later planting dates in the most recent decades. Consideration of sea surface temperature (SST) anomalies (deviations from longterm mean values) in the Tropical Pacific Ocean allowed the separation of groups of years with frequently low FHB risk (negative SST anomalies, La Nin˜a like years) and years with frequently high FHB risks (positive SST anomalies -El Nin˜o like years, and near-normal SSTneutral years). Southern Atlantic SST anomalies were then included to separate years with different FHB risks in El Nin˜o-like years and Neutral years. However, the consideration of these anomalies did not result in an improvement. Our results suggest that increased spring rainfall linked to warm sea surface temperature in the Pacific after the 1980s was associated with higher frequency of FHB epidemics in southern Brazil.

A Predictive Model for Daily Inoculum Levels ofGibberella zeaein Passo Fundo, Brazil

“…Coincidently, the ENSO phases in each period corresponded to "neutral," "warm," and "cold," respectively. This is in agreement with reports [9] that FHB epidemics are likely to be more severe in "neutral" and "warm" than in the "cold" phase, in this part of the world. The model constructed with the data between September 15 and October 15 in 2008, 2009, and 2010, respectively, was used to predict the density of G. zeae spores in the air of Passo Fundo.…”

“…In Brazil, similar to other parts of the world, an increasing frequency of severe FHB outbreaks has been reported over the last two decades (especially after 1990) resulting in severe yield losses [1,8,9]. No wheat varieties are immune to FHB and resistance is generally controlled by several genes of moderate/weak effect and they are defined genetically as quantitative trait loci (QTL).…”

Survey of mycotoxins in Southern Brazilian wheat and evaluation of immunoassay methods

“…The DON levels determined in our study are in agreement with previous reports in the country, using chromatography methods. However, year-to-year (or decades) and region-to-region variations are expected, given the strong dependence on seasonal weather conditions as well as management practices that contribute to suppress the disease and mycotoxin levels (Del Ponte et al, 2009). For example, Furlong et al (1995), two decades earlier, analyzed 38 samples of commercial wheat grain and found DON in 55 % of the samples, but at lower mean and range (400 to 590 µg kg ) found in this study, including all samples.…”

Endophytic fungi from Vitis labrusca L. ‘Niagara Rosada’) and its potential for the biological control of Fusarium oxysporum

“…The genus Fusarium causes some of the most economically damaging plant diseases, affecting viticulture as well as other plant species throughout the world (Del Ponte et al, 2009;Matos et al, 2009). In grapes, Fusarium, mainly the species Fusarium oxysporum f. sp herbemontis, penetrates into root tissues, which can lead to plant death .…”