In the Hawkesbury Valley - for two centuries the food bowl of Sydney - Adrian Maguire despairs of ever getting reform to what he sees as a malevolent grocery industry dangerously dominated by Coles and Woolworths.

Mr Maguire, 23, has an apple and stone-fruit orchard, Enniskillen, in the beautiful Grose Vale, and says the system denies farmers sustainable prices for their produce.

Shoppers might gasp at their checkout bills, he said, but sometimes the prices he gets don't even cover transport and packaging, let alone the cost of growing and harvesting a crop.

Despite a similar chorus of complaints from farmers across the nation, yesterday the Australian Competition and Consumer Commission inquiry into the grocery industry said it could find no evidence of anti-competitive behaviour by the big supermarket chains towards suppliers of fresh produce.

"When you hear that the ACCC have found [nothing], it really leaves you walking with a limp," Mr Maguire said.

The commission's chairman, Graeme Samuel, warned the National Farmers' Federation in April that he had been presented with no "smoking gun" against Coles and Woolworths, which account for about half of the fresh produce sold in Australia.

The federation's submission said: "There appears to be an increasing gap between farm gate and retail prices. The food supply chain is only as strong as its weakest link, and in this regard, it is vital that all participants are profitable and sustainable in the long term."

The NSW Farmers' Association said: "Increasingly, Australian farmers sell their produce into markets that are dominated by a small number of very large-scale corporations. Individual farmers have very little ability to negotiate fair contractual arrangements, as their customers often have significant resources and use these to their advantage."

However, the commission has concluded: "There is no across-the-board evidence to suggest that retail prices for fresh products are going up by a greater percentage than farm-gate prices. It is certainly the case that the large price increases in many fresh items over recent years cannot simply be attributed to the retailers.