This year may be the season that oilseed rape crops benefit from a foliar nitrogen spray at flowering, as showery weather disrupts fertiliser plans.

Wet weather meant the late February/early March dressing did not happen for some growers, said Mark Tucker, UK marketing and agronomy manager at Yara.

See also: Wet weather heightens risk of stem rot in oilseed rape

“And now we are in the third week of March and the crop is well developed, undergoing stem extension.”

The forward crops are a result of the milder winter and higher residual nitrogen in soil.

Therefore, the delayed second dressing that went on last week may well be the last, as crops will be too big for spreading solid fertiliser.

© Tim Scrivener

“This could have ramifications for these forward crops, especially as it looks like there may be an extended flowering period and the crop could run out of nitrogen.”

Mr Tucker explained that if crops were short of nitrogen, they started scavenging nitrogen from pod walls and leaves and this could occur during the critical seed fill stage

“The last 2-3 weeks is a critical time for seed formation and you could see a yield hit if the canopy goes off.”

Foliar feed in early April

Therefore, this could be the season that growers consider going for a foliar feed in early April to keep the canopy going for longer.

“You just need enough [nitrogen] to extend the life of the canopy by 1-2 weeks.”

One option is to go for a specialist micronutrient product, as some also include macronutrients delivering 3kg/ha of nitrogen.

Another option is to go for liquid urea and there is well established research showing yield responses of 0.25-0.33t/ha when applying 40-50kg/ha of nitrogen at flowering.

This can be simply added to the sclerotinia fungicide mix in early April, so an extra sprayer pass is not needed.