Rains blamed on the La Nina weather pattern have slashed hopes for two of the major crops in Indonesia, the Asian agricultural powerhouse, including bringing to an end a period of surging palm oil growth.

US Department of Agriculture officials have, in an influential report, halved to 500,000 tonnes their estimate for growth in palm production in 2009-10 in Indonesia, the world's top producer, blaming wet weather.

The forecast for 2010-11 output was cut too, by 1.5m tonnes to 23.0m tonnes, given forecasts for further above-average rainfall, blamed on La Nina, a disruptive weather pattern linked to a cooling in Pacific water temperatures.

"National meteorological forecasts for continued higher-than-normal rainfall through December have convinced most producers that oil extraction rate yields will remain below normal for at least the next few months," the briefing said.

The fall in palm oil production growth to 2.4% in 2009-10, and 9.5% in 2010-11, represents a significant fall from the average rate of 18.5% over the previous decade, a surge, driven by rising plantings, and which drove Indonesia above Malaysia to the top of the global output league.

'Pest pressure' 

Rains have also set back rice, of which Indonesia is the world's third-biggest producer, after drought in growing regions last October was followed by eight consecutive months of above average precipitation � even during the April-to-August period normally considered the dry season.

The freak conditions have "caused a host of problems", including hampering crop drying, and so impairing rice milling rates, and encouraging pests and crop disease.

The USDA slashed its estimate for the 2009-10 rice crop by 1.7m tonnes to 37.1m tonnes, and its forecast for 2010-11 by 2.0m tonnes to 38.0m tonnes, "owing to the likelihood that increase disease and pest pressure will prevent the country from achieving normal trend yield growth".