An organic farmer from Western Australia who took on his GM canola-cultivating neighbour on contamination claims has failed in his bid to appeal against a large legal costs bill.

Kojonup farmer Steve Marsh sued his former childhood friend Michael Baxter over a claim that he lost organic certification for 70% of his farm due to contamination from Baxter’s GM canola.

Marsh sought $85,000 in damages but was instead ordered to pay court costs of about $804,000.

On Thursday, the West Australian court of appeal dismissed the appeal.