Crop diseases’ resistance to some traditional fungicides means arable farmers must change their methods of infection control in the forthcoming season, a conference heard.

Frontier Agriculture’s seminar at the John Innes Centre in Norwich was one of seven UK events to present findings from the first year of trials under the firm’s “3D Thinking” initiative, aiming to understand some of the issues facing future food production.

Speakers outlined results from nine trial sites around the country, including at Pulham Market near Diss, where thousands of individual plots were planted to compare the yields of commercial winter wheat varieties in a variety of fungicide programmes.

David Robinson, Frontier’s head of trials and innovation, said although yellow rust had been prevalent in wheat last year, his main concern was septoria – a disease which had previously been controlled with a fungicide group known as triazoles.

But he said the trials had proved that the disease’s tolerance of the chemical had grown to a point where it was no longer effective in eradicating the infection, although triazoles could still work as protectants if used in tandem with more expensive SDHI treatments.

His key messages to farmers were: Do not rely on one single fungicide, make sure the programme starts early enough to protect the lower leaf layers, and be prepared to adjust it in response to changing weather and soil conditions.

He said: “Going into the 2015 season, all our data is says the same thing. The problem with resistance build-up with triazoles means their performance is dropping off quite dramatically.

“Most of you are sitting on high-yielding varieties which will require a robust fungicide programme. Relying on triazoles because they are cheap is not the way to go.”

In the longer term, Mr Robinson said farmers should consider using wheat varieties with stronger disease-resistant characteristics.

The conference also discussed effectiveness of cover crops and different cultivation methods in suppressing blackgrass weeds, and Edward Downing, fertiliser technical manager, explored the optimum balance of phosphates to achieve the best sustainable yields.

Andrew Melton, regional agronomy sales manager, opened the event on an optimistic note. He said: “As farmers we are eternal optimists and in light of a growing population and continued volatility we established last autumn’s crops again in wonderful conditions so, despite all the dramas of 2014, I am confident 2015 could be our best year ever.”