Risk assessment for fusarium mycotoxins in wheat

Some fungal species can grow on crops and foodstuffs and produce toxic chemicals. Of widely varying toxicity to humans and animals, these chemicals are called mycotoxins. To keep mycotoxin levels below set limits, it is important to follow best practice – which includes the completion of a risk assessment.

In cereals, mycotoxins can result from fungi that either develop from field-borne infections (fusarium mycotoxins and ergot alkaloids) or in stored crops (ochratoxin A).

There are legal limits for fusarium mycotoxins deoxynivalenol (DON) and zearalenone (ZON) in wheat intended for human consumption and guidance limits for feed grain.

The owner (farmer, merchant or processor) is legally obliged to ensure grain is safe for human consumption. Depending on end use, processors may require a lower limit at intake than the legal limit for unprocessed cereals to ensure finished products conform to legal limits.

Crop assurance schemes are designed to help farmers comply with food laws. They include an audit of the risk assessment and an AHDB risk assessment score is required on the grain passport.

Pre-flowering risks

Region

DON and ZON levels in wheat tend to be highest in southern and eastern England. Higher humidity in coastal areas may increase risk.

Previous crop

Crop residue on the soil surface is the major source of inoculum. The greatest risk is after grain maize or forage maize. Rotations should aim to minimise wheat sown after maize.

Cultivation

Complete burial of debris by ploughing is most effective at reducing the risk, while risk is highest with direct drilling. Intensive non-inversion tillage (three or more passes with discs or tines) is more effective at reducing risk than reduced non-inversion tillage (one or two passes).

Wheat variety

The risk assessment includes varietal resistance based on the AHDB Recommended List (RL) rating for fusarium ear blight.

At-flowering risks

T3 ear fungicide

Using an appropriate dose of an approved T3 ear fungicide with activity against fusarium and/or mycotoxin production reduces the risk.

Rainfall at flowering

Wet weather promotes fusarium development. The score is based on total rainfall during flowering (GS59–69 – full ear emergence to end of flowering).

Pre-harvest risks

Rainfall pre-harvest

Wet weather promotes fusarium development. The score is based on total rainfall from GS87 (dough development stage/start of ripening stage) to harvest.

Post-harvest risks

Keep control of your grain quality

Follow best sampling practice to capture quality and condition before grain leaves the farm.

• Follow best practice to minimise fusarium mycotoxins in cereals
• Assess risk pre-flowering and consider T3 fungicide (ear spray)
• Take accurate measurements of rainfall at flowering and pre-harvest (use the rainfall risk tool)
• Calculate final risk score at harvest and record on grain passport
• Check purchaser requirements to determine whether mycotoxin testing is required

Covering thousands of sites across England, Scotland and Wales, our map-based tool shows how much rain has fallen during the critical winter wheat flowering and pre-harvest periods. Use this information to help calculate (DON) risk assessment scores required on the combinable crops grain passport.

The following resources will help you assess and manage mycotoxin risk. They will also help you to obtain composite and representative samples for testing for DON and ZON (where required by the end-user).

Agrochemical residues, mycotoxins and other major contaminants in cereals and co-products have been monitored independently since mid-1980s. Find out about our research that aims to help ensure the safety of the UK grain and its end-products.