Guy Poskitt said: "We don't dispute a minimum wage - I say living wage, living price. But many growers will have already have signed contracts for next year with a wage rise of a couple of percent in mind and now they face a 10 per cent rise.
"There will be a huge impact on growers from the living wage and there will be less and less British produce if we don't sort this. There are opportunities to take labour out of carrot production, but less so in crops like pak choi or strawberries.
William Soutar, chief executive of prepared foods supplier William Jackson Food Group, told the conference: "The living wage will see catering outlets de-skilling their kitchens so it's an opportunity for us. An unintended consequence is that companies will change their labour strategy and invest in automation and efficiency."
Nick Gale, managing director of WJFG-owned produce processor MyFresh, said: "For a business with 550 employees, it's a seven-figure issue. We will have to aggressively automate the industry, and quite rapidly. My ambition is to have half the number of people in my operation within the next five years."