Resumen

MOSCHINI, R.C  y  MARTINEZ, M. I. Variabilidad climática y expresión de la fusariosis de la espiga de trigo en la región pampeana. RIA. Rev. investig. agropecu. [online]. 2015, vol.41, n.3, pp.289-297. ISSN 1669-2314.

In Argentina, wheat Fusarium head blight (FHB) is predominantly caused by the fungus Fusarium graminearum. The sporadic nature of FHB in the Pampas region, associated to weather factors, led to the development of weather-based disease forecasting systems. Infective events were identified by head wetting resulting from synchronic occurrence of precipitation and high relative humidity, around wheat anthesis (susceptible critical period for infection). Retrospective model predictions (1932-2013) in three Pampas region sites (Paraná, Pergamino and Mar del Plata) were able to analyze the effect of the El Niño Southern Oscillation (ENSO) phenomenon and climate change on the disease. The trend lines of FHB incidence predictions showed light positive slopes, larger towards southern Pampas region. Positive values of annual anomalies (difference between annual predicted FHB incidence and the median of the historical series) decreased to the southern Pampas region in the first period analyzed (1932-1972) and increased in the second period (1973-2013). To the southern, positive and negative anomaly values increased in El Niño and La Niña years respectively. For explaining this behavior, the effect of the two extreme phases of ENSO phenomenon over the probability distribution of dry spells was analyzed. From daily precipitation data (1932-2013) of the three Pampas region sites grouped by the occurrence of El Niño or La Niña episodes, conditional precipitation probabilities were modeled taking account first order Markov chain process and seasonal trend. From the models, probability distributions of occurrence of at least 7 day dry spells in 15 day periods were derived for both phases. For the three sites, differences between phase probability curves clearly occurred from November to December, where wheat anthesis is concentrated in southern Pampas region.

Palabras clave : Fusarium head blight; El Niño Southern Oscillation; Climate change; Markov chains models; Dry spells.