| Grain
Flowering, fusarium and forecasts:
Mycotoxin management in wheat
Concern across the global supply chain about the presence of mycotoxins in grain means many countries have
developed tools to predict contamination risk. The UK is no exception, with simple paper-based tools to pioneering
forecasts becoming available over the last few years.
n the UK, AHDB’s
paper-based and
online mycotoxin
risk assessment
and guidelines
contain best
practice information. Supported by
the supply chain, these tools
provide a relatively simple way to
manage mycotoxin risk.
I
At this time of the year, the scores
in the ‘pre-flowering’ section of the
risk assessment are already known
– because they are based on ‘risk
factors’ before or during drilling –
such as region, previous crop,
cultivation method and variety.
At and after flowering, however,
the more tricky elements of
fusarium mycotoxin risk need to be
38 | Farming Monthly | May 2018
dealt with – those driven
predominately by the weather.
Many growers consider a T3 ear
wash fungicide application during
the wheat flowering period to limit
infection of wheat ears by Fusarium
species, reduce head blight and
lessen the risks of mycotoxin
development.
The industry, though, is under
increasing pressure to reduce
fungicide use. This pressure is not
just from the public but also from
the chemistry itself. For example, it
is known that an azole applied at T3
can make septoria tritici more
resistant to this class of chemistry,
even if it is not the intended target
for the spray*. It is clear that
accurate information on fusarium
infection risks could help with both
the targeting of sprays and the
management of higher-risk grains
(e.g. through the use of harvesting,
sampling and storage strategies).
As part of the effort to provide a
heads-up risk service, AHDB has
funded work** over the last three
years to investigate the provision of
‘real-time’ fusarium infection risk.
The ADAS led work used a simple
‘calculator’ and key risk information
– average county-level daily rainfall
and flowering progress information
– to estimate infection risk on a
weekly basis during the flowering
period.
One of the key questions in the
research was how the forecast risk
married up with mycotoxin levels
detected in the grain. To provide an
answer, the research team used
actual deoxynivalenol (DON)
mycotoxin scores from several
hundred grain samples and
compared results against the
forecast risk from the calculator and
the paper-based risk assessment.
Out of all the samples, only six
samples in 2016 and 2017
exceeded the 1250µg/kg threshold
for food safety. The calculator
forecast picked up two of these
samples as being at high risk,
whereas the paper-based risk
assessment picked up one.
There are two key observations
from these findings. Firstly, the
study years were relatively low risk
(97% of samples <500 mg/kg
DON). Secondly, both ways of
forecasting were not perfect. In
2017, for example, although rainfall
at the county level was low,
showers caused more significant
accumulations at the field level and
disrupted T3 applications.
In 2016, two samples tested
high. Although there was not
obvious reason why, it was
subsequently found that the fields
in question had had large amounts
of maize in the rotation (if not in the
previous crop) and had maize
game strips.
All other samples that were
forecast by both tools to be at high
risk, had DON levels well below
threshold. This means that both
approaches tend to overestimate
the risk of DON being present in the
harvested grain – which is
preferable to risk being
underestimated.
With so many factors influencing
actual risk, prediction systems will
vary in their performance. But,
when it comes to the management
of mycotoxin risk, the industry has
come a long way in recent years
and improvements continue to be
made. The UK is heading in the
right direction.
For the latest information on risk
management, visit
cereals.ahdb.org.uk/mycotoxins
*Adding a multisite product reduces
resistance risk.
** Validation of fusarium infection
risk calculator with AHDB mycotoxin
risk assessment and actual DON
result (Final Project Report 593)
www.farmingmonthly.co.uk