Barley growers should inspect crops for signs of mosaic virus, as higher than normal levels have been seen in crops this season, according to Nickerson.

“Symptoms in non-resistant varieties are the strongest we have seen for many years,” said the firm’s plant pathologist, Paul Fenwick. “The mild winter means there’s a lot more leaf area to be affected, so the virus is much more visible.”

Once the weather warmed up, many crops would grow away from the virus, but badly affected areas may suffer a 30-40% yield penalty, he said. “If you’ve got it, there’s no chemical control, so the only option is to sow resistant varieties.

The virus lives in the soil and persists for 15-20 years, he added. It is a particular problem in colder seasons and areas where barley features heavily in the rotation, such as the Cotswolds, he noted.