OILSEED RAPE crops have developed rapidly over the past fortnight and growers must take steps to control well established crops, Masstock has warned.

At the firm‘s SMART trials farm at Brotherton in Yorkshire, well established crops are ahead of normal and canopies are too big, said trials co-ordinator, David Langton.

“Crops have gone off like a coiled spring and have already reached a Green Area Index (GAI) of 3.5.

“That‘s the canopy size the crop should reach at its optimum point of growth, which shouldn‘t be for several weeks yet.”

A GAI of 2 is more normal for this time of year, he said.

While this growth surge is similar to last year, he believes lodging risk could be greater this season, as there were fewer establishment problems last autumn and residual soil nitrogen levels are higher.

“Unless growers take precautionary steps now, crop canopies will be inefficient and they could suffer severe lodging and lower yield,” he said.

Growers should apply a fungicide with good growth regulatory activity, such as Caramba (metconazole), he suggested.