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Poster: Epidemiology: Pathogen Dispersal


Spatiotemporal analysis of wheat blast epidemiology (Magnaporthe oryzae Triticum pathotype) under natural field conditions
K. MILLS (1), L. Madden (1), P. Paul (1), D. Salgado (1) (1) The Ohio State University, U.S.A.

Wheat blast is an emerging fungal disease of wheat caused by the Triticum pathotype of Magnaporthe oryzae. In years when weather is conducive for disease development, growers can suffer total crop losses. In order to understand the epidemiology of wheat blast, it is important to characterize the pattern of disease spread within a field. This pattern provides clues about the characteristics of the pathogen that affect the spatiotemporal dynamics of the disease. In this study, inoculum build-up and temporal and spatial spread from naturally occurring in-field disease foci (hotspots) were investigated in six 27 x 27 m2 plots at three locations in Bolivia during the 2015 growing season. Plots were assessed for spike blast incidence and severity every 3 days. Assessments were made on a grid, with twenty spikes rated every 2.7 m. Hotspots increased in size over time and were associated with the highest disease ratings. Initially, plants adjacent to the hotspots had higher disease levels than plants located farther from the hotspots. As the disease progressed the steepness of the disease gradient decreased away from hotspots, and high levels of incidence and severity were observed throughout the plots. This trend was observed across the three locations. Preliminary spatial analyses suggest that hotspots are important in-field sources of inoculum.