Saskatchewan's 23,000 canola farmers are getting more nervous after a second Canadian company was banned from exporting the crop to China.

Last week it was Richardson International and Tuesday it was Regina-based Viterra.

"I think this is a very big concern," Tracy Broughton of the Saskatchewan Canola Development Commission said.

The Chinese government said pests were found in previous shipments.

Some wonder if the ban is political, retaliation for Canada's detention of a prominent Chinese executive.

Broughton said no matter the cause, a long-term ban could hurt farmers and the province's entire economy. She noted Canada exports about $2.7-billion of canola to China each year. Half of that is produced in Saskatchewan.

Tracy Broughton of the Saskatchewan Canola Development Commission says that no matter the cause, a long-term Chinese canola ban will hurt farmers. (Jason Warick/CBC)

She said efforts to find new, stable markets must be intensified.

"Farmers are pretty disappointed," she said.

"As a canola industry we've been very involved in discussions with the provincial government [and] federal government to figure out how to get this issue resolved, but also how to diversify our markets so our farmers aren't in this position again."

Delmas-area farmer Martin Prince agreed diversification would help, but there's not much individual farmers can do in the short term. He isn't signing any sales contracts under the current turmoil, but will have to sell his crop eventually.

"It does not serve us well, in the interim. It's testing my patience is what it's doing," he said.

"There will be an impact, and the longer it takes for this issue to be resolved, the more risk there is to me as a grower."

Prime Minister Justin Trudeau has voiced concern over the canola bans. Trudeau said the Canadian government would like to see evidence of the contamination in the canola shipments.