Incidence of FHB in Winter Wheat
Results from the Defra CropMonitor project (1986 - present) have shown that the incidence of
FHB in the UK has been sporadic. However, levels of FHB over the past decade (1998-2008)
has increased compared to the previous decade (1989-1998).
Incidence of FHB at GS 75 in England and Wales
Over 55% of the samples assessed during the 2008 survey showed symptoms of FHB. This level is lower
than that seen in 2007 but is up on the 10 year average (39%). The increased disease levels over
recent years are likely to be a result of the wet weather during anthesis, changes in agronomic
practice and the relative prevalence of the pathogens responsible for the disease symptoms.
Monitoring of FHB pathogens
Since 1998, FHB pathogens have been isolated from diseased wheat ears collected by the survey
(data shown from 2000).
The predominant pathogen isolated from FHB symptoms varies from year to year, although, it is in
generally either M. nivale/majus or F. poae. In 2008, as in 2007, M. nivale/majus
were the predominant pathogens. In 2008, with the exception of F. graminearum, all species were
isolated at levels lower than in 2007; in 2007 and 2008 over 25% of the surveyed samples had infections
caused by F. graminearum.
In the UK, F. culmorum and F. graminearum are the major cause of deoxynivalenol (mycotoxin)
contamination of wheat grain. Since the start of isolations in 1998 there has been a switch
in predominance of these two pathogens, with the incidence of F. graminearum exceeding that
of F. culmorum for the first time in 2002. F. graminearum is generally regarded as a more
aggressive pathogen and causes higher levels of mycotoxin contamination in grain than
F. culmorum.
Factors, which may be attributed to the increased prevalence of F. graminearum, include
weather conditions at anthesis, changes in tillage practice and the increasing use of maize in rotations.
Region incidence - 2008
In 2008, the levels of FHB pathogens isolated from each region were lower than in 2007. The lowest
levels were found in the North East (17%) and the highest in the South East of England (85%).
M. nivale/majus were the predominant species isolated from all regions other than the
East Midlands and the South East of England where F. graminearum predominated.
The highest level of F. graminearum was found in the South East and East Midlands, with
49 and 35% of samples, with on average 3 and 4% of ears per sample infected respectively.
