Distribution, toxin production and control of fusarium head blight pathogens in the UK

Abstract

Levels of FHB have been monitored in England and Wales since 1986, with the species responsible for symptoms determined since 1998. Between 1998 and 2001 the predominant species responsible for the FHB symptoms alternated between Microdochium nivale and Fusarium poae. In 2002 and 2003, no single FHB pathogen predominated. The frequency of isolation of F graminearum has steadily increased since 1998 and, at the same time isolation of F culmorum has declined. Chemotyping F culmorum and F graminearum by PCR analysis showed that both deoxynivalenol (DON) and nivalenol (NIV) chemotypes were present in UK populations. DON chemotypes predominated in both populations, however high numbers of NIV producers were also identified. Regional differences in chemotype were observed for F culmorum where a higher proportion of NIV producers were found in the south and west of England, and a higher proportion of DON producers in the north and east. No differences were seen in chemotype distribution for F graminearum. In separate fungicide trials differential control of the FHB pathogens was apparent depending on the product applied. Several fungicides based on triazole chemistry reduced the level of toxin-producing species and the subsequent levels of DON in the grain. These fungicides had little or no effect on the level of M nivale. The application of fungicides based on strobilurin chemistry effectively controlled M nivale but not the Fusarium species. There was evidence that the application of some fungicides, may lead to an increase in the level of DON in the grain.