Moisture key to successful OSR – Dick Neale, Cam Murray
The inclusion of oilseed rape on many UK farms has reached crisis point ...
With decisions being made now on individual farms whether to continue with the crop albeit in a reduced area, or remove it from the rotation all together.
The general picture is that Cabbage Stem Flea Beetle (CSFB), pigeons, slugs and very dry autumn conditions have played havoc with establishing the crop as well as hindering its ability to get away in the spring.
However, this is not reflected across the whole of the British Isles, in fact the true picture shows huge variability in the conditions of crops, with some good-looking crops coming into the spring further north in Scotland and the west.
So how has this happened?
Why are some crops better able to cope with the challenges of pests and climate? Dick Neale of Hutchinsons believes much of this comes down to soil conditions at drilling.
“Whilst no-one can question the havoc that CSFB has brought to crop emergence over the last two seasons across most areas of the UK, this has been vastly exacerbated by the very dry conditions in many areas where the crop has been drilled into, hampering its ability to get up and away.”
He points out that once oilseed rapeseed has started germinating it cannot be allowed to dry out in the following 7 days. “If the seed dries out 4 days later it will not establish – the soil needs to be able to provide that moisture.”
“So last autumn where seed was planted into dry and dusty seed beds, germination and subsequent crop emergence was slow and erratic, and the resulting staggered emergence was like a picnic for the pests as they picked plants off as they emerged.”
“However if soils at drilling are moist, the seed can imbibe all that moisture and emerge evenly, thereby diluting the beetle pressure and the crop and will have a much better chance of getting up and away.”
Cam Murray Hutchinsons northern regional technical manager, supports this approach and has seen the benefits of wetter autumn soils on establishment across many the oilseed rape crops he walks in East Lothian.
“OSR remains a key break crop in this area; conditions are generally wetter so we don’t worry too much about moisture in the seed bed in August. Also, our rotations are longer with many only including OSR one-in-six or seven years, the shortest would be one-in-five years, therefore we have not had the pressures as a result of the wheat-rape scenario’s that many arable farmers face further south.”
Mr Murray recognises that CSFB is definitely creeping up and it is becoming easier to find damage from the beetles in the autumn. “Later drilled tend to be at higher risk from this pest, and although not at the levels seen in the south, it is a nevertheless a problem on the increase.”
“Pigeons are a nuisance particularly in fields that have trees around the boundaries, which present a “home base” for the birds, and although the crop recovers, it suffers from late flowering, canopy damage and is ready to harvest later- just making an already challenging job that much harder.”
OSR crops are generally looking good as they come out of the winter, he says, putting this down to getting them in early enough in August so that they established well and developed strong stems- robust enough to withstand pigeon attack.
“The aim is to get an established plant with a good framework but this means getting the crop drilled by the second week of August. The first week of September is just too late – crops that went in this time last year, have not established as well as those drilled earlier and have generally struggled – particularly against pigeon onslaught.”
Seed rates are kept low, 20-25 seeds/m2 for hybrids and 30-40 seeds/m2 for conventionals. “This gives thick enough crops with the right canopy architecture – however taking this approach does mean it is essential to minimise losses as much as possible.”
“It’s these crops that yield the best and we would expect yields of 4.0/5.0 t/ha so it’s obviously working.”
Mr Murray cites the example of one farm that uses subcasting with a precision drill where the seed rate is kept down to 25 seeds/m2 with the aim of 18-22 established plants at 600ml spacing – and the crops look fantastic.
He underlines the importance of pre-loading the seedbed with nutrient N P & K, pointing out that the newly emerged crop must suffer no delay in the availability of nutrients.
“We also know that phosphate and Potassium vastly improves the speed and vigour of establishment.”
“Liquids work well as a starter fertiliser for OSR. Direct the spray to one side of the row or temper the amount of fertiliser that’s put down directly with the seed. I would recommend 16:16:0 that we use at 100l/ha at drilling.”
“Primary-P also provides a very concentrated, available but persistent form of nutrients so about 10kg/ha is more than enough.”
Variety choice is key
“To date Campus and the conventional Anastasia have been firm favourites and delivered consistently.”
“However, we are staring to see Turnips Yellows Virus this far north with infection levels as high as 75-80%! This underlines the need for a TuYV resistant variety and with many growers moving onto the high yielding hybrid Aurelia, which also has 8’s for light leaf spot and phoma.”
“Growing a TuYV resistant variety also take out the need to spray with pyrethroids.”
“Clearfield varieties are becoming increasingly popular, as weed issues such as runch become more increasingly difficult to control.”