Deoxynivelenol (DON) is sometimes produced when fusarium attacks growing crops the main species being Fusarium graminearum and Fusarium culmorum, which cause head blight in crops.  The EU has established maximum levels for DON in grains for human consumption and advisory limits for animal feedstuffs, which are translated into UK rules.

UK Legal DON Limits in Grain Intended for Human Consumption

  DON (ppb)
Unprocessed common wheat and barley 1250
Unprocessed durum wheat and oats 1750
Flour 750
Finished products 500
Infant food 200

EU Guidance Values for DON in Grain Intended for Animal Feedstuffs

  DON (ppb)
Feed Grains 8000
Complete feedstuffs for pigs 900
Complete feedstuffs for calves, lambs and kids 2000

The chain in the UK manages this issue through several methods. An early warning system (CropMonitor) monitors the level of fusarium infection as the crop develops and is used to assess the level of risk across the country. At harvest time, a large number of samples are collected and tested by grain merchants and processors such as flour millers to assess the overall level and risk. A formal monitoring project is run by HGCA which checks on levels in grain as they are delivered through the season. The amount of testing and control when grain is delivered varies according to the level of risk in each harvest year.

The main risk factors which can lead to the presence of DON are: presence of the relevant species of fusarium; rain at he time when crops are flowering; and rain at harvest time leading to delay in optimal harvest timing. Farmers can assess and mange the risk to their crops by following the procedures set out in the HGCA’s risk assessment guide which is based on experience over several harvests.