INTEGRATING CULTIVAR RESISTANCE AND FUNGICIDE APPLICATION TO MANAGE FUSARIUM HEAD BLIGHT OF WHEAT

摘要

Fusarium head blight (FHB) is a devastating disease of wheat in the southern cone of South America. FHB represents one of the main constraints for wheat production in Uruguay, where moderate to severe outbreaks have occurred in one of every four yearsover the past two decades. In order to optimize disease control measures, cultivar resistance and fungicides were investigated and their interaction was evaluated. Commercial cultivars and advanced lines were characterized under intermediate to high disease pressure in nurseries and field trials during 2011 to 2013. Few commonly grown cultivars had high levels of resistance and comprised 7, 10, and 15% of the area planted to wheat in 2011, 2012, and 2013, respectively. Metconazole alone or in combination with epoxiconazole were the most effective fungicides in controlling FHB, by reducing FHB index (FHBI), Fusarium damaged kernels (FDK) and deoxynivalenol (DON) content and increasing grain yield. Although some mixtures of triazoles + strobilurins andtriazoles + carboxamides + strobilurins reduced FHBI and FDK, they increased DON content. Fungicide efficacy in reducing FHB and DON and in increasing grain yield was greater in a moderately resistant cultivar (INIA-Genesis 2375) that in a susceptible one (INIA Don Alberto).These results suggest that it may be possible to manage FHB by cultivar resistance and timely fungicide applications with recommended triazoles.