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 hundreds 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, which had the potential to give a significant uplift in yields.

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. Don't rely on a single mode of action.'

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

Andy Hartley, national trials manager, said disease resistance was becoming increasingly important in choosing wheat varieties, particularly with some fungicides under threat from EU legislation.

He said: 'Yield is still key, but quality varieties present new opportunities. Wheat breeders are refocusing on the fact that we are looking more at traits and genetics.'

The 3D Thinking trials incorporated longer-term studies on the effectiveness of cover crops and different cultivation methods in suppressing blackgrass weeds, with measurements coupled with time lapse photography and multi-spectral aerial drone imagery.

The conference also discussed improving performance with precision farming data 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 by reflecting on a year of perfect growing conditions, creating a surplus which, allied to political issues in Europe, forced a downturn in prices.

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.'