The Potato Marketing Corporation (PMC) has accused a Western Australian potato grower and grocery retailer of breaching a binding commercial agreement.

The PMC is set to take businessman Tony Galati to court, alleging he deliberately planted more than his designated quota of approximately 6,000 tonnes of potatoes.

The PMC is a statutory body tasked with regulating the amount and variety of potatoes grown in Western Australia.

Tony Galati gave away 200 tonnes of potatoes for free from his Spud Shed stores in January, which he was unable to sell because they exceeded his quote.

Potato farmers in the state's south-west said Mr Galati's potato giveaway caused a glut, that left many growers unable to shift hundreds of tonnes of their own produce.

PMC chief executive Peter Evans said the regulator reached a binding commercial agreement with Mr Galati in 2013, which took into account Mr Galati's unique position as both a grower and a retailer.

Listen Duration: 4 minutes 15 seconds 4 m 15 s Listen Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Peter Evans says Tony Galati breached a commercial agreement with the Potato Marketing Corporation ( Bridget Fitzgerald ) Download 1.9 MB

Mr Evans said Mr Galati broke that agreement by "significantly" overplanting more than his set quota and the PMC would be seeking action through the Supreme Court.

"In effect he has distorted the market for potatoes and affected price, and therefore returns for other growers," he said.

Mr Evans said Mr Galati's actions impacted growers across the state.

But he said the court action was a simple case of Mr Galati's alleged breach of a commercial agreement.

"We have a commercial agreement with Mr Galati that outlines how much he should be growing," he said.

"We have surveyed evidence about the area that he has planted and there is a significant difference [in what he is growing]."

Tony Galati has been contacted for comment.