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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


What’s happening in oilseed rape in November/December

The majority of crops are now well established, with October’s wet weather boosting soil moisture to help struggling crops grow away from Cabbage Stem Flea Beetle damage. Some early-drilled crops are looking quite well-forward and there may be concerns around keeping the crop standing over winter. However, some winter kill and pigeon feeding can reduce crop biomass over the next few months.

Disease control is now the main focus and although Phoma is present in crops, several varieties have good resistance scores which has helped to prevent early infection in these crops. As a result, there has been little spraying in October. However, the risk of light leaf spot infection increases from November and growers should regularly monitor crops for early signs of this disease.

Leaf samples tested by Bayer’s SpotCheck service in late October has identified light leaf spot across several counties in the East and North, which is not surprising given the wet weather we have had over the past two months.

Pay particular attention to risk-factors in your crop, levels of light leaf spot inoculum from previous crops and the resistance rating of the variety you have used. Any variety with a resistance rating below seven has a higher risk of infection this autumn.

Where growers adopt a one-spray strategy for autumn disease control, using a fungicide such as Proline, with activity against both Phoma and light leaf spot can be an advantage. Keeping the foliage clean for as long as possible will be of benefit come spring, when spore splash in the upper canopy can quickly affect pods.

The early signs of light leaf spot are difficult to identify, so growers can make use of Bayer’s SpotCheck service to test leaves for infection. Results are available within a few days, which can help time protectant fungicide sprays.

It will soon be time for applications of propyzamide for weed control where required, so growers could consider adding a fungicide to the tank mix. Not only can this save additional passes on already wet ground, the risk of light leaf spot infection is greater from November onwards.

The wet weather in October has dampened aphid activity and suction traps have not picked up huge numbers of peach potato aphid. This is good news for oilseed rape crops given the lack of chemical control options now to prevent Turnip Yellows virus.



What’s happening in oilseed rape in October

There is fairly positive news from those that got crops drilled in early august, with good establishment, even in the East with higher cabbage stem flea beetle (CSFB) pressure. However, crops that were drilled later in August and early September have suffered with the dry weather and lack of soil moisture.

CSFB populations increased in line with the warmer weather in September, but most August-drilled crops that established well, have escaped significant attack from the adult beetles. We could still see high larval attack, but won’t see the damage until the spring.

The more forward crops will be at lower risk of Phoma infection, but smaller plants, either from later drillings or pest attack, will be at risk. As Phoma infection is mainly driven by rainfall, fields in areas that received high rainfall in the last week of September will need to be closely monitored, as this will have increased the disease risk. Regular monitoring will ensure fungicides can be timed effectively.

Fields with smaller plants, and where varieties have a disease rating of 6 or less, the threshold for spraying is 10% of plants affected. Larger plants and varieties with a higher disease rating, wait until 20% of plants are infected before spraying. AHDB’s Phoma leaf spot forecast is useful at predicting the date at which 10% of oilseed rape plants could potentially show symptoms of Phoma infection.

While larger plants are less at risk of Phoma, the opposite is true for light leaf spot. Early-drilled crops will have been exposed to the wind-borne ascospores for longer, and there is no treatment threshold for spraying before stem extension. Fungicides act only as protectants.

Where growers plan to only apply one fungicide spray before Christmas, or where there is doubt about being able to get back on to land later in the autumn, Proline has the benefit of providing activity against both Phoma and light leaf spot.

If a second application is possible, an additional application of Proline will provide a boost of protection against light leaf spot, to see the crop through to spring.

Bayer’s SpotCheck service is now available to test oilseed rape leaves for signs of light leaf spot, and assist with fungicide timings.

Priorities now:

  • Assess crop establishment and variety disease rating to determine Phoma threshold
  • Consider using Proline to control both Phoma and light leaf spot if only one spray planned
  • Use Bayer’s SpotCheck service to test for non-visible signs of light leaf spot and help spray timings


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

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