Monitoring risks of mycotoxin contamination caused by fusarium head blight pathogens in winter wheat

Abstract

Fusarium head blight (FHB) of wheat can be caused by a number of different Fusarium species, including F. culmorum, F. graminearum, F. avenaceum, F. poae, Microdochium nivale and M. majus. All these pathogens, with the exception of the Microdochium spp. produce mycotoxins, which can have an adverse effect on human and animal health. The main aim of this project was to monitor and investigate fusarium disease in winter wheat and to advise industry of seasonal and regional risks of disease incidence and mycotoxin contamination.

National surveys of incidence of FHB disease and pathogen levels were carried out in co-operation with the Defra winter wheat disease survey between 2006 and 2008. Data showed that although FHB levels were low in 2006, disease levels in 2007 and 2008 were the highest, and third highest recorded respectively (86 and 64%), with the predominant pathogen being M. nivale/majus. Isolations of the toxin-producing F. graminearum were also high, with over 25% of crops infected in both years and an average of >2% of ears affected nationally in 2008 (the highest recorded).

Due to the elevated levels of detection of this pathogen, alerts were issued via the CropMonitor website advising of the increased risk of toxin contamination in grain in 2007 and 2008. These predictions were validated by results from mycotoxin monitoring (RD- 2006-3288) indicating that toxin levels were elevated in 2007 and 2008. Analyses of the data collected indicated that the most important factors in incidence of F. graminearum were region (17% of the variation accounted), weather, specifically spring temperature (28% variance accounted) and agronomic factors (previous crop, cultivation method and sowing date) (13.7% of the variation).

Other weather factors such as temperature and rainfall at flowering need to be investigated and incorporated within the model to improve the predictive capability. In-season monitoring of FHB inoculum build-up and disease development was undertaken at five sites to try and provide an early indication of the risk from FHB, and thus provide intelligence on the likelihood of disease development on the ear. Annual differences in disease levels were evident, with levels in 2007 being particularly high. Alerts were issued each year indicating the likely risk from FHB infection, taking into account the weather forecast for the flowering period.

Results indicate that this type of monitoring could assist in identifying risks of FHB earlier in the season, enabling growers to respond. Further work on investigation of the role of in-season monitoring in disease risk prediction and further development of the models is recommended.