A warning has gone out for farmers to check paddocks for stray canola plants, which may be genetically modified.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 4 minutes 45 seconds 4 m 45 s NSW Riverina farmer Gai Marshall told Michael Condon farmers should check any stray canola plants if they do not want GM on their farms Download 2.2 MB

Contamination of non genetically modified (GM) crops with GM material has been in the headlines, in the wake of the high profile case in Western Australia.

In that case, organic farmer Steve Marsh tried to sue his neighbour Michael Baxter, after GM canola from Mr Baxter's farm blew onto Mr Marsh's property.

Segregation of non-GM crops is big business as GM-free canola commands a premium of at least $50 dollars per tonne, especially when exported to Japan.

Currently about 80 per cent of Australia's canola is non GM.

Gai Marshall, from Berrigan, became alarmed about potential contamination when she spotted canola plants in a paddock where canola had never been grown.

The canola plants tested positive as being genetically modified, and Ms Marshall is advising other farmers to be alert to potential contamination.

"We found quite a number of plants in a paddock where we have never grown canola," she said.

"So we pulled them out by hand and tested them and they all tested positive to being GM.

"We have no idea how they got there, perhaps within a load of fertiliser.

Ms Marshall, who is a former member of the NSW Farmers Association GM Taskforce, said if other farmers wanted to stay free of GM contamination in order to qualify for premiums the should be vigilant about stray plants coming onto their properties.

"I also believe that the testing kits should be more easily available at Department of Primary Industries or Local Land services so we can protect our higher value markets," she said.