Winter wheat has seen as "significant" decline in Canada as well as the former Soviet Union, thanks to hangover from the dismally wet conditions that dogged this year's crop, the Canadian Wheat Board has said.

The board, the world's biggest wheat seller, has disputed claims by the US Department of Agriculture's Ottawa bureau that winter wheat sowings rose this year.

The bureau said in a report that winter wheat, usually a minority crop in Canada, was "likely" to have seen an increased area in 2011-12, and were potentially limited only by the levels of certified seed.

"Due to the unfavourable weather conditions that have left fields very wet, planting winter wheat is being seen as an attractive option to help soak up the water," the briefing said.

'Just too wet' 

However, the board said that Canada's Prairies, responsible for more than 90% of the country's wheat area, were "looking at a significant decline in winter wheat acres this year over last year" thanks to wet and cold weather in the country for much of the period since spring.

Part of the problem was in crop delays caused by the poor weather, which left farmers tied up with harvest during the winter wheat sowing period, which typically peaks in September, board spokesman John Lyon said.

And, even for growers with time available, the sowing window "was just too wet for many farmers to seed", he added.

Stubble sowing

While winter wheat can beat spring wheat for yields by more than 20%, the fall in sowings envisaged by the board would not have the same impact as in the former Soviet Union, where the balance between the crops is more even.

Even in a good year, winter wheat accounts for only about 5% of the 10m acres or so of wheat that Canadian farmers plant each year.

The country's cold winters pose a significant threat to the crop, as they do in much, but not all of Russia and Ukraine, and where it is planted, it is often seeded in rapeseed stubble, which holds the snow needed to protect seedlings from sub-zero temperatures.