US officials in Beijing have cast doubts on official estimates of a bumper 2009 grains harvest, warning of drought damage to corn and of a sharp fall in wheat production rather than the rise China and Washington are expecting.

The US Department of Agriculture's Beijing team said that, "despite various official reports on a bumper corn harvest", it expected production to slide to 150m tonnes.

"Yield was substantially impacted by adverse weather patterns… [including] prolonged drought at critical growth stages and cold temperatures in July-August in parts of the north east," the attaches said in a report.

The wheat harvest would end up at 106m tonnes, hurt by weather setbacks "during multiple growth stages".

"The four factors that adversely impacted the winter wheat crop in 2009 were: winter drought, plant disease, hot and dry wind before harvest, and rain damage around harvest time," the report added.

Differing opinions 

The figures are sharply lower than forecasts from both Washington and, in particular, Beijing, whose estimates of robust grains production have been contradicted by some private analysts.

Both Washington and the official China National Grains and Oil Information Centre believe China's wheat production has risen at least 2m tonnes from last year's 112.5m tonnes.

While attache forecasts do not represent official USDA data, on-the-ground intelligence from Washington staff has a big influence on changes to forecasts published in the department's highly-influential monthly world crop reports.