Don’t rush to rip up oilseed rape crops that appear borderline, Ian Munnery of Elsoms Seeds says.

Leave them and reassess in the spring, he suggests. “Crops with 10-20 plants/sq m can still deliver respectable yield, especially hybrids.”

Neil Donkin, a Countrywide Farmers agronomist in the west, agrees it is worth waiting. “Oilseed rape has a fantastic ability to compensate, plus the sheer cost of ripping up and re-drilling a crop, makes it worth seeing how they come through the winter. If it is a mild winter the crop will continue to grow.”

Even populations as low as six plants/sq m have a chance to recover, he says. “If you have six good plants/sq m I’d go with it. Even if it is six poorer plants I still think I’d wait.

“That said, if you’re struggling to find a plant, like in one crop I walked yesterday, then forget it.”

An application of foliar feed, including phosphate, can also help once crops reach three to four leaves, he suggests. “It can do remarkable things to rooting, but that’s if growers can get it on.”

Both men also agree it is not a good idea to patch-drill a spring variety into a winter-sown crop. “Experience shows their maturity dates rarely correspond and harvesting immature spring-sown seed can be costly,” Mr Munnery says.

Instead take out blocks to re-drill with spring varieties, and then treat them as separate crops, Mr Donkin advises.

• Not all agronomists are so keen to wait – see Crop Watch