Canopy adjustment vital for OSR output

Pigeons may prove a blessing for some oilseed rape producers looking to start nitrogen dressings this season.


“Provided the birds have left the growing points alone, they will have made some of these otherwise big crops much more manageable,” says David Langton, who runs Masstock’s Best of British Oilseeds initiative


“There is huge potential there – we just need to manage and look after the canopy properly.”


Many crops established so well last autumn that they began stem extension before cold weather set in.


“That’s unusual and means many are at high lodging risk.


“Some of these crops are going to need high rates of Caramba growth regulator to keep the canopies upright,” says Mr Langton.


A key message from the BoBO trials at 15 sites across the country is that canopy management should go right back to drilling.


Growers must adjust seed rates more in line with expected establishment, urges Mr Langton.


Various cultivation methods are being assessed.


At Yattendon Estate, Berks, three are being tested – conventional ploughing, Vaderstad Rapid drilling and rolling, compared with using a Vaderstad TopDown working to 18cm followed by drilling, and finally the TopDown fitted with a Biodrill operated at only 6cm.


“Establishment here ranges from 100% to 70%, with the best in Rapid-drilled plots,” says Mr Langton.


“Elsewhere it’s been as low as 22% after min-till.”


With all signs pointing to an impending drought, deep rooting will be crucial for good results.


That is best achieved by holding off nitrogen, except for very thin crops, and concentrating on applying a fungicide offering growth regulation, he explains.


“We’re looking at rates of 0.6-1.2litres/ha of Caramba depending on the situation.”


Caramba has a stronger growth regulatory effect than Folicur (tebuconazole), he notes.


A BoBO trial at Salisbury last season confirmed that delayed nitrogen works.


In total, the crop received 225kg/ha (182 units/acre) of N, with 25% applied in early March.


“We always use split dressings – the first for manipulating the canopy and the second, as late as we can get through, for building yield,” says Mr Langton.


Splitting the balance and delaying over half of it by only a fortnight produced an extra 0.5t/ha (4cwt/acre) (see table), he adds.


“The only justification for going earlier would be on sulphur-deficient crops where growers rely on combined N/S products like Double-Top.


These crops need 100kg/ha of SO3 by mid-March.”


andrew.blake@rbi.co.uk