Early autumn showers in Europe should boost growth of rapeseed crops but have come too late to prevent an area decline in France where drought disrupted late-summer sowing, analysts and traders said.
The European Union and Britain have seen production of rapeseed, their most common oilseed crop, wane in the past two years due to adverse weather and insect problems.
In France, heavy rain since last week is not seen preventing a further decline in the crop area, after it shrank to 1.1 million hectares in the past two harvests from around 1.5 million in preceding years.
"Our estimate is that the area will be below 1 million hectares," a French oilseed trader said.
"The rain could be good for crop emergence and may boost yield potential, but it's too late for sowings."
Farmers had initially planned sowings equivalent to the area harvested this year, traders and analysts said.
In Britain, like France, farmers have also been trying to curb insect damage, after the banning of insecticides known as neonicotinoids blamed for harming bees.
"Some crops have started to develop well, especially for those who tried new drilling techniques like companion cropping, but others later drilled that did not have vigorous early growth are starting to see pest damage," said analyst David Eudall of the Agriculture and Horticulture Development Board.
Britain's rapeseed area is expected to decline again, as growers are deterred by rising costs and falling yields.
For this year's harvest, the area in England was down 29% at 351,000 hectares, according to government data.
Conditions were more promising in Germany and Poland.
"The weather was dry during the planting window but I think there was just enough rain to get the work done without major problems on a national level," one German analyst said.
"Soil is dry and we need more rain as we go into the autumn but I think the overall picture is currently satisfactory."
Germany's rapeseed area could be expanded by 70,000-100,000 hectares from the 954,000 hectares harvested this summer, he estimated, saying farmers were encouraged by reasonable 2020 yields.
In Poland, winter rapeseed sowing is also complete and should at least reach the level drilled for this year's harvest, said Wojtek Sabaranski of analysts Sparks Polska.
"Rapeseeds were sown mostly in a timely manner," Sabaranski said. "Heavy rainfall in late August/early September was conducive to crop establishment."
Poland harvested about 830,000 hectares this summer.