Historically good growing conditions have helped drive down fresh food prices, but Coles managing director John Durkan has warned consumers they may not last.

Mr Durkan said there is a "raft" of fruit and vegetables coming onto the market at the same time, with supply overtaking demand to trigger deflation.

Market share gains enjoyed by Coles in the past two years are "fading" as a result of slowing momentum, broker Citi warns. Credit:Bloomberg

Consumer price growth fell well below the Reserve Bank's target band in May, with a sharp 4.1 per cent fall in the price of fruit and vegetables.

"What we have seen in the last quarter is unprecedented growing conditions in Australia, in particular in bananas," Mr Durkan told analysts at a Wesfarmers strategy briefing on Wednesday.