With fusarium risk at higher levels than last year, an accurate measure of pre-harvest rainfall can help growers complete field risk assessments for mycotoxins and ensure clean wheat is stored separately from potentially contaminated grain, maximising returns.
In terms of rainfall-related risk, the latest AHDB-funded fusarium risk report, carried out by ADAS, shows 73 per cent of the UK wheat crop to be at moderate risk, 16 per cent at high risk and 10 per cent at low risk, with a small proportion at very high risk.
The largest areas of high risk crops are in Kent, Norfolk, Cambs, Shrops and Staffs due to rainfall exceeding 40mm when some crops in these areas were flowering, according to the report.
However, risk varies significantly, even on a single holding, according to Dhan Bhandari, senior scientist at AHDB. “Fields may be close by but have different rotations which affects the score. The risk assessment should have been filled in as the season progresses with the last bit of rainfall data just before harvest.”
Ideally rainfall data will come from a local weather station or a rain gauge, he said. “Don’t guess the figure.”
AHDB has produced a risk assessment form which covers risk factors such as previous crop, cultivation method, rainfall, fungicide application levels and variety.
Although the critical flowering period is over, factors such as lodging can also increase the likelihood of wheat being infected, he warned. “If you have got a potentially higher premium crop, prioritise it in terms of harvesting and try to segregate it. Different fields could have different values. If it scores 16 or more don’t mix it with a 15.
“Where FHB [fusarium head blight] symptoms have been spotted in crops, adjust combines to minimise the retention of light fusarium-damaged grains and chaff.”