Growers across the country should be starting to think about nitrogen (N) for rape crops around now.
Speaking on the most recent edition of the Teagasc Tillage Edge podcast, crops’ specialist Shay Phelan said that farmers should get out and start examining crops on a field-by-field basis.
“I have been on farms recently where adjacent fields of rape had widely different Green Area Index values,” he said.
“As a rule of thumb, crops with a low Green Area Index will need N now.
“In the case of crops that got slurry or chicken manure in the autumn, straight N will suffice at this time.
Nitrogen fertiliser
Phelan said that low index crops will need fertiliser over the coming days; in the case of crops with a high index figure, there is not the same requirement to sow fertiliser at this stage.
“Crops with very high Green Area Index figures may well need very little fertiliser at all,” he said.
The specialist confirmed that a Green Area Index, or GAI app, can be easily downloaded onto growers’ phones.
“The app is very easy to use. It can also recommend accurate N fertiliser application rates for all rape crops.
“But the bottom line remains that of growers getting out into the fields and walking all their rape crops as a matter of priority.”
Sulphur for rape crops
Phelan also pointed out that rape crops will need sulphur now. The two options are Ammonium Sulphate Nitrate, or ASN or SulCan.
“Growers who had not previously ordered ASN may well find it hard to get their hands on it at this stage.
“In such cases the only option available may be SulCAN. But the bottom line is that rape crops need added sulphur now.”
Disease
Where disease in rape is concerned, Phelan highlighted the threat of light leaf spot at this time of the year.
“Buds are now starting to appear within the canopy of crops growing at Oak Park. Rape at this stage of growth is very susceptible to light leaf spot.
“If flower buds get infected, they will be lost to the crop. And, obviously, this will impact negatively on the final yields achieved.
“The vast majority of crops will need a fungicide over the coming days, probably something like Proline.
“Faster growing crops might also need a growth regulator applied. But time is of the essence in getting this work carried out. Boron should also be applied, if required,” he stated.