Oilseed rape has seen mixed fortunes this season with cabbage stem flea beetle and dry conditions mainly to blame for crops being abandoned in some cases.
There has been significant loss of this year’s planted oilseed rape area, with large regional differences being observed, according to a farmer survey by Kleffmann Group.
The Kleffmann Group panel consists of 403 UK rape growers and calculates an original planted area in autumn 2018 of 581,030 hectares of winter rape. However, 68 farmers have reported failed crops amounting to 6.28 per cent of the total original planted area. This is 36,000 hectares lost. In the 2017/18 season, the percentage loss was 1.62 per cent so autumn 2018 has been much more hostile to rape survival by a factor of nearly four times, according to the survey.
Significant regional differences were also noted from the survey; Scotland, for example, had the lowest area of oilseed rape lost at just 0.91 per cent of the original planted area, closely followed by the North East region at 1.36 per cent.
The South East region had the highest area of failed crop at 12.6 per cent, followed by Yorkshire and the Humber region at 9.75 per cent. Between these extremes are the remaining regions; East Midlands suffered 3.5 per cent loss, South West, 4.34 per cent, West Midlands, 5.34 per cent and Eastern region, 7.29 per cent.
Agrii agronomist and farmer David Felce, who covers Cambridgeshire and Bedfordshire says oilseed rape is ‘a very mixed bag’. “A lot is down to cabbage stem flea beetle, not helped by dry conditions last autumn.
“Often where the crop had survived adult flea beetle damage, those crops are now showing high levels of larvae in the stem and some of those crops are looking a little ragged. If they are in the leaf petioles it is not quite so bad but if they are in the main stem – the meristem where the flower buds are forming that is of more concern.”
When deciding whether to continue with an OSR crop, as well as CSFB damage there are other factors to bear in mind, says Mr Felce. “If you have also got a not particularly high plant population and black-grass and grass-weeds, the decision may be around is it worth nurturing the crop knowing you are going to struggle to control grass-weeds?”
But it is a hard call to write off a crop and growers may be restricted regarding a follow-up crop depending upon herbicide choices made for the OSR crop, says Mr Felce.
If the decision is made to continue with the crop, ensuring good nutrition through use of phosphite products and supplementation with manganese, boron and sulphur can be helpful, says Mr Felce. “Given a fighting chance we know rape can recover incredibly.
“Decide where to set your spend and probably do not go too far as there could be an impact on yield [from stem damage]. Do not let light leaf spot in otherwise it will lower yield.”
Frontier agronomist Andrew Roy, who covers North Yorkshire, Durham and Northumberland says while rain has been somewhat scarce in his area, pigeons have not.
“Flocks are now increasing, grazing what are generally well established oilseed rape crops. With the ongoing crop growth we have experienced, I am not unduly concerned about our feathered friends at the moment – they may even be doing us a favour.
“Cabbage stem flea beetle larvae are now evident in the leaf petioles of many OSR plants, although not at the extreme levels reported further south.”
Rob Fox, who manages AHDB Strategic Farm West, Squab Hall, on the outskirts of Leamington Spa, Warwickshire, says he has had big problems with oilseed rape establishment this season.
Working across three farms Mr Fox says: “On one farm we had no rape planned. On our farm we lost 100 acres of 170 acres mainly due to dry conditions. Where we did get a bit of moisture it managed to grow away from cabbage stem flea beetle but establishment was very low on heavy ground because of the dry and that that did establish got hammered by cabbage stem flea beetle.
“We sprayed off 100 acres in November and that will go into spring barley.”
On the third farm 40ha was drilled, says Mr Fox. “We’ve got 100 acres – there is the odd thin patch. It was drilled on Bank Holiday weekend when there was a bit of rain; it is patchy but potentially will make a crop.”
Looking ahead, Mr Fox says if he grows oilseed rape in the future he will do it differently. “I would use home saved seed at a very high seed rate, get it in early and get it away. It is not a recipe for the highest yielding crop but a recipe for an even crop. If you can get an average crop it is still worth it.”