Prairie farmers are expected to plant record canola acres this spring as the crop looks very profitable, but the tighter rotations may lead to other agronomic issues in the long run, according to crop specialists.

After seeding a record 18.9 million acres of canola in 2011, Canadian farmers are poised to shatter that record in 2012. Industry participants are forecasting seedings in the 20 million- to 22 million-acre range, or above.

Many of those additional acres will be planted in land that was unseeded in 2011 due to adverse spring conditions. However, strong canola prices are encouraging some farmers to tighten their rotations and even plant canola on top of canola in some cases.

A canola-on-canola rotation is believed to reduce yields by 10-15 per cent, said Grant McLean, a crop management specialist with Saskatchewan's Agriculture Knowledge Centre in Moose Jaw. However, larger disease issues are also a concern.

"Farmers are trying to run a business, so they are looking at dollars per acre, but there are some agronomic risks," he said.

The industry has improved varieties over the past years to deal with disease, but McLean said there were signs that resistance to the blackleg fungus and other diseases was starting to break down in some locations. Concerns over clubroot are also becoming more prevalent in Western Canada, particularly in Alberta.

Flea beetles and lack of moisture utilization are additional problems posed by planting canola in too tight a rotation, said Anastasia Kubinec, oilseeds specialist with Manitoba Agriculture, Food and Rural Initiatives at Carman.

Crop rotations of at least one year in three, or one in four, provide the optimal results for canola, said McLean. He noted that even rotating different varieties of canola can provide benefits, as producer consistently using the same variety may also be creating a situation where disease could break through.

In the past 10 years, canola rotations have moved more and more toward every other year, said Kubinec, noting that in 2000 about 20 per cent of farmers were planting canola every other year, and now over 50 per cent are on a two-year rotation.

Strong prices mean farmers will continue to push rotations as long as the profits are there, said Kubinec. However, "there will come a time when we'll run into serious issues," she added.

"The industry has done an exceptional job with providing the tools to let us have the tight rotations we currently have," but those improved varieties currently being planted do not live up to their full potential on a two-year rotation, said Kubinec.

If producers planted 10 per cent less canola, they could improve their yields by 25 per cent in the long run with the rotational improvements, she added.