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Oilseed Rape

We know that growing oilseed rape can be challenging so we have gathered together everything you need to know about oilseed rape here. From establishment to harvest we can provide insight about crop management and protection to help maximise yields.

Posted a year ago

September

What’s happening in oilseed rape in September

While much of the oilseed rape in the south and east was drilled in August, there is still some drilling to be done, especially in the north, and where cereals are coming off fields later than normal, or due to sub-optimal soil conditions.

Drilling at the beginning of September into moist, good quality seedbeds can still potentially miss the first Cabbage Stem Flea Beetle (CSFB) migration, but variety choice becomes more important. Vigorous growth is essential, so a hybrid variety is a good option.

The threat from early light leaf spot infection and club root can be reduced by drilling in September and, while it can mean a higher chance of flea beetle attack at the seedling stage, plants often suffer less from larvae attack in the spring, having been exposed to the adults for less time in the autumn.

Regardless of drilling date, applying both nitrogen and phosphate at, or shortly after emergence, will help plants grow away strongly.

Where flea beetle is a challenge, crops should be monitored weekly, but growers should be mindful of the urge to spray. Resistance to pyrethroids is widespread, so application must be justified against CSFB levels and the risk to beneficial invertebrates.  If the first spray is not successful, there is no benefit in applying a second.

Growers will need to balance weed pressure against crop investment, especially in marginal oilseed growing areas. However, by taking out competitive weeds early the crop will have a better chance at establishing well this autumn.

Post-emergence herbicides should be focused on removing volunteer cereals and competitive broad-leaved weeds. There are a number of options available for post emergence herbicides in oilseed rape, however it is important not to let the growth stage of some weeds, such as mayweed get too large, as control will taper off. Regular field walking will be required to time sprays correctly.

Priorities now:

  • Ensure later-drilled crops go into good quality seedbeds with sufficient moisture
  • Apply starter fertiliser including nitrogen and phosphate to get crops up and away quickly
  • Monitor weed emergence and remove volunteer cereals and broad-leaved weeds early

July

What’s happening in oilseed rape in July

As harvest gets underway, take care to assess the level of maturity across the field. Patchy and poor establishment, damage from cabbage stem flea beetle (CSFB) and pigeons, and lack of soil moisture means that some crops are very variable.

Pod samples should be representative of the field, taken from a range of plants and not just from the headland and tramlines. Once the majority of seeds in each pod have tuned from green to brown, a desiccant spray can be applied if necessary. Remember that cooler weather can delay senescence.

July is also a good time to make finalise your varieties for next season.

When making your choice, consider your main priorities: yield, fast establishment, spring growth, disease resistance, weed control, or specialist markets.

Hybrid varieties, such as those from DEKALB offer a range of benefits to suit most situations, and all include pod shatter resistance to assist with harvest timing flexibility.

In areas with high CSFB pressure, fast-establishing varieties can help the crop grow away in the autumn. Similarly, varieties with strong spring re-growth and tolerance to the larvae can help to protect yield potential.

In the west and north, or where CSFB is a lesser concern, you may want to focus more on varieties with good disease ratings. All DEKALB hybrid varieties have double phoma resistance, which reduces the risk of phoma stem canker. If light leaf spot is a concern, look for varieties with a resistance rating of 7 or higher.

Turnip yellows virus is an increasing concern, particularly with the loss of key active ingredients to control aphids in the autumn, so look for varieties with TuYV resistance.

Clearfield varieties are beneficial where broad leaved weeds are hard to control, particularly charlock, or when growing a companion crop like mustard to deter CSFB.

And finally, those looking for alternative markets for oilseed rape should look to HOLL varieties, which can offer substantial premiums and oil bonuses.

Priorities now:

  • Take representative samples of pods pre-harvest to assess maturity
  • Finalise variety choice based on your priorities and agronomic needs

June

What’s happening in oilseed rape in June

June can be a quieter time: the key work is accurately assessing seed maturity and deciding when to spray pre-harvest glyphosate towards the end of the month, if you are desiccating. 

As always, it’s a tricky balance: spray too early and reductions in yield can be as much as 1-2% with each day of seed filling lost, but the wait does potentially increase the risk of pod-shatter. Farmers can at least take comfort that all Dekalb varieties have inbuilt pod-shatter resistance, reducing the risk of seed shedding, allowing greater flexibility with spray timing. 

Judging maturity means more walking: Crop maturity and therefore timing of desiccation may vary a lot between farms as well as within individual fields. Of course, a lot of oilseed rape crops have suffered this year at the hands of pigeons and cabbage stem flea beetle, so it’s important to take a representative sample of pods from wherever the majority of yield is being held within the canopy. Take a sample of 20 pods and as a rule of thumb, if the majority of the seeds per pods have changed from green to brown, the crop has reached the earliest correct stage for spraying and seed moisture of 30%. 

Consider spray quality, for optimum coverage and penetration we recommend using 200-250L water in thicker crops and using low drift nozzle or formulations if possible. We also suggest spraying earlier in the day during hot weather periods, when relative humidity is highest. The current hot dry spell does favour modern Roundup products which perform well in these conditions, show minimal drift and are rainfast if the weather does change.   

Of course, OSR easily hides a lot of grass weeds which could be more of an issue in the following crop – so another significant benefit of desiccation at this time is dealing with any substantial weed populations. 

Once glyphosate has been sprayed farmers need to be patient and wait for the pods and stems to be fully fit for combining which could take up to three weeks or more. 

Priorities for this month:

  • Ongoing assessment of seed maturity (test multiple locations)
  • Spray pre-harvest glyphosate at optimum timing and coverage

May

What’s happening in oilseed rape in May

Majority of crops have reached mid flowering, and the rain forecast for early May will be gladly received. However the accompanying warmer temperatures will increase the risk of Sclerotinia, so any outstanding first sprays (of products such as Proline or the newly-available Aviator (bixafen + prothioconazole)) need to happen as soon as possible, if the risk remains high. A follow up spray may be required if the flowering period continues past 3 weeks from the first spray. Monitor crops and utilise forecasting systems to aid fungicide decisions. 

Light leaf spot (LLS) can still pose a threat and thriving in warm, moist conditions means it will keep cycling through crops and may move up the canopy. Any Aviator or Proline applied against Sclerotinia will also help reduce LLS. 

Seed weevils may be present in places, creating entry points for pod midge. Best-practice monitoring is needed to measure weevil incidence and treat them as soon as levels reach threshold, but the rain may help keep their incidence down.   

Weather patterns earlier in the season mean a huge range of growth stages right now across the country (often within one field) so pest-management investment will have to be decided on a field-by-field basis. Given that oilseed rape is one of the only paying crops this season, protecting its yield remains critical.

Priorities this month: 

  • Any outstanding first Sclerotinia sprays need to happen urgently in early May. A second spray may be needed for crops sprayed in April. 
  • LLS remains a risk so keep monitoring
  • Seed weevil may reach threshold and justify a spray.  

April

What’s happening in oilseed rape in April

Warmer, drier weather is, at last, helping surviving oilseed rape crops grow away from flea beetle and waterlogging. As they move rapidly towards and into flowering, it is particularly important to watch out for Sclerotinia and maintain light leaf spot protection, especially following the epidemic levels of disease identified by Bayer’s SpotCheck this season.

The Sclerotinia risk is likely to vary very widely from field to field with more-forward crops  starting to flower while those struggling to recover are well behind and seem certain to flower over a much longer period.

Extended flowering, of course, means a greater exposure to Sclerotinia, so a repeat flowering spray may be necessary to see these crops through their vulnerable stage. 

Extra protection to reduce light leaf spot cycling and build-up should pay particular dividends in many cases too.

With its proven activity against both Sclerotinia and light leaf spot, the newly-available chemistry of Aviator (bixafen + prothioconazole) will be especially valuable here. As an SDHI, bixafen’s well-recognised physiological value in maintaining green leaf area offers additional help to backward crops.

While a pollen beetle spray hasn’t been necessary for most forward crops, those flowering later and coming into the green/yellow bud stage may need protecting with a timely insecticide spray. And no-one should forget how damaging seed weevil – and ensuing pod midge infestations – can be.

Priority this month (location dependent):

  •        Manage Sclerotinia spraying carefully to crop flowering period

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