It has been a turbulent 18 months for oilseed rape, following the loss of neonicotinoids, challenging weather conditions and an influx of cabbage stem flea beetle. But with few other break crop options available, it remains an important crop in the rotation, both financially and agronomically.
Despite its rollercoaster growing season last year, many growers were left pleasantly surprised by the resilience of the crop when it passed through the combine this harvest.
Despite heavy cabbage stem flea beetle infestations causing concern early on, Andrew Blazey, agronomist at Prime Agriculture, covering Suffolk, Cambridgeshire and Essex, says last year’s crop performed better than expected, leading to some growers to increase their OSR area this year.
He says: “In our area, 3.5 tonnes/hectare is good and a lot of crops this harvest averaged 3.5-4t/ha.
“With flea beetle, where establishment was okay and growing conditions were good the crop tended to compensate.”
Mr Blazey says that crops with bigger biomass last year kept flea beetle in the leaf petioles rather than the stem.
“If you can get a variety with good autumn vigour, like InV1035, you do increase your chance of having a decent biomass hopefully lessening the effect of the larvae.
“Last year I had InV1035 on two farms in three blocks – one drilled early August, one block drilled mid-late August and one drilled early September. The yield was consistent across all three blocks.”
In South Wales and Pembrokeshire, with low flea beetle pressure, crops were averaging over 5t/ha on some farms, says Agrii agronomist Dai Llewellyn.
This year, crop drilled in late September has not liked the wet weather but has no flea beetle damage.
He says: “In the wet conditions it was very noticeable that the hybrid varieties are considerably faster growing and more resilient than some of the conventional varieties. Even the HOLL varieties, which are hybrid, were very slow this year.
“Last year Nikita did well but InV1035 was the highest yielding over three or four farms.”
Mr Llewellyn puts this down to autumn vigour allowing for later plantings, and a kind autumn.
“A lot was drilled in the last two weeks of September and we even had some was drilled in October.
“We are quite fortunate that it is mild here, so rape will generally keep growing well into December. If the winter is kind and you have got a crop that is not too thick and you can get some nutrients in it and get it to 2-3 leaf stage, you have got the potential for a good crop.”
Although the oilseed rape area has fallen slightly on Mr Llewellyn’s farms this year, this is mainly down to where it sits in the rotation, and it remains a profitable break crop.
He says: “My oilseed rape acreage has dropped a little – around 10% – but that is due to mixed farming and rotations generally. Most of my rape rotations are minimum one in five, and sometimes one in seven, and that’s what leads them to get the better yields. It has been the highest gross margin crop on the bulk of my crops this year.”
Although flea beetle pressure has been low for his growers this year, Mr Llewellyn predicts the pest will eventually migrate to the area.
He says: “If you look at the flea beetle advance, there are lots of crops being lost in Monmouthshire and Glamorgan but nothing in Pembrokeshire. Last year I did not spray any OSR in Glamorgan for flea beetle, so it is advancing west, but it has got a big jump to go into Pembrokeshire.
“We had quite a lot of pressure here on some swedes very early on in July/August, but we haven’t seen any in late crop. I thought then that we would have more of an issue in the rape crop than we have actually had.
“Because we are lucky that we haven’t had the pressure, a lot of my better growers have been companion cropping with buckwheat and clover which has worked very well.”
For growers uncertain about the future of the crop within their rotation, Mr Blazey recommends focusing it on fields that are kind for establishment, before giving up.
He says: “Make sure you get your fertility and soil structure right. It is often with hindsight, but drill when you think conditions are optimum for establishment, whether that is early or later on.”
And with limited break crops in the agronomy toolbox, oilseed rape remains an important crop in the rotation, not just financially but agronomically.
“For us, pulses tend to be inconsistent and are more about setting up for a first wheat, whereas the price of rape is good so if you can get a good crop in the ground and it stands on its own two feet. If you can get it in and away it does spread workload at a busy time of year.”
Another benefit of growing InV1035 is BASF’s OSR Establishment Risk Share Programme, which covers all InVigor winter oilseed rape hybrid varieties, adds Mr Blazey.
“One of my growers lost some crop and was grateful for the money back guarantee this season.”
Even where pest pressure is high, the resilience of the crop should not be underestimated, according to Matthew Keane, BASF agronomy manager, Suffolk, with some crops that had very high levels of flea beetle attack last autumn still seeing good yields.
BASF strip trials of InVigor varieties saw spring larval counts as high as 80 larvae/plant.
Mr Keane says: “I thought I was going to lose the whole trial, but we harvested it as normal and where we had high larvae counts, we still had yields of 5t/hectare or over. There are cases of really quite severe damage, but the crop has an unnerving ability to compensate for a lot of damage. There is a tipping point somewhere but some crops that look really badly damaged can surprise you.”
With much debate over drilling dates and cultural controls to get the crop off to the best start, Mr Keane says the only real defence against flea beetle is drilling the crop in the right conditions.
“If conditions are good for oilseed rape to go in the ground and there is available moisture and you can get it in and growing fast, that is your best defence regardless of calendar date or variety.
“There is evidence of people putting DAP with the seed at drilling or seeing good results where its more fertile, such as where there’s muck beforehand, but the only overriding concept to get OSR going and fast, is good drilling conditions.”
Speed and evenness of growth is key, with prolonged germination a problem in droughty conditions, Mr Keane adds.
“It is important to select a variety with rapid autumn growth as larger plants will be likely to withstand more damage from adult flea beetle. The difference between being at just one leaf emerged versus two could make the difference between success and failure.”