Mycotoxin risk tool for wheat refreshed for 2023

Monday, 15 May 2023

Farmers can calculate rainfall-related mycotoxin risk assessment scores online via a weather-based mapping tool.

Access the mycotoxin rainfall tool

About the tool

The tool reveals rainfall levels at hundreds of sites across England and Scotland during the critical winter wheat flowering and pre-harvest periods.

First released in 2019, the tool has been refreshed for the current season.

Dhan Bhandari, who manages grain quality research at AHDB, said: “Rain splash spreads the pathogens responsible for head blight. Some species produce mycotoxins in infected ears, so it’s important that risk is managed.”

In winter wheat, the first rainfall-risk period is during flowering – GS59 (ear completely emerged above flag leaf ligule) to GS69 (flowering complete).

The second key rainfall risk period is GS87 (hard dough, thumbnail impression held) to harvest.

Rainfall risk scores

Growth stage

Rainfall total

Risk score

Rainfall at flowering


> 80 mm


40–80 mm


10-40 mm


< 10



Rainfall pre-harvest

(GS87 to harvest)

> 120 mm


80–120 mm


40–80 mm


20–40 mm


< 20 mm


Generating risk scores

Once the date range for each period is known, it can be entered into the tool, which then calculates the amount of rain that fell and displays the corresponding risk score at each site.

If no field-level rainfall data is available, risk scores from a nearby site in the tool can help guide the completion of the mycotoxin risk assessment.

Further information

For complete information on the risk assessment and links to T3 fungicide guidance, visit:

Contaminants monitoring

Mycotoxins, agrochemical residues and other major contaminants in cereals and co-products have been monitored independently since the mid-1980s.

How we help ensure the safety of UK grain and its end products