Mycotoxin risk assessment scores can now be calculated automatically, thanks to a new rainfall-related tool from AHDB. CPM reports.

Covering thousands of sites across England and Scotland, a new map-based tool from AHDB shows how much rain has fallen during the critical winter wheat flowering time and pre-harvest periods – allowing users to assess mycotoxin risk.

“The pathogens that cause head blight are spread by rainfall. If they reach the ear at the right growth stage, they can infect it,” says Dr Dhan Bhandari, who manages grain quality research at AHDB.

“Once infected, some of these species produce mycotoxins – so it’s important that they are managed.”

Infection risk

In winter wheat, the first risk period is during flowering – GS59 (ear completely emerged above flag leaf ligule) to GS69 (flowering complete). As infection occurs via fresh anthers, the duration they are present is critical – this period rarely exceeds 10 days. The second key rainfall risk period is GS87 (hard dough, thumbnail impression held) to harvest.

Once the date range is known for each period, this is entered into the AHDB rainfall tool. Then the amount of rain that fell during this time is calculated at each site and the corresponding risk scores shown. If no field-level rainfall data is available, risk scores from a nearby site can help guide the completion of the AHDB mycotoxin risk assessment.

Wet conditions at flowering not only increase ear infection risk but also make the application of fungicides a challenge. For the management of ear diseases, sprays should be applied when the first anthers are visible (GS63–65). The effective window for control is narrow and the power of a T3 diminishes rapidly after the optimum spray timing.

According to Paul Gosling, fungicide performance manager at AHDB,  a T3 should not be a default in any wheat fungicide programme. “If it is dry when anthers are out, then the disease pressure is unlikely to warrant the spray. However, if a T3 is considered necessary, azoles should be combined with a multisite to help protect the azole from resistance. A multisite will also provide added septoria control.”

For more information on mycotoxin management, T3 timing and fungicide performance visit: ahdb.org.uk/mycotoxins