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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 7 months ago

Oilseed rape - Bayer Crop Science

December to January

What’s happening in oilseed rape in December and January

Oilseed rape crops are looking good in general, having grown away well in most areas. Flea beetle larvae is present, but where crops have established, they are coping well.

The good canopy growth in many crops means that Phoma stem cankeris now less of a threat, but in less-well-established crops some late Phoma infection could take hold. However, Light leaf spot continues to pose a risk to crops. Leaf samples can be sent to Bayer’s SpotCheck service to help identify the disease, which can be hard to spot in the field. Request a sample pack from the SpotCheck page.  Results will be emailed to you within seven working days of receiving the sample.

If a fungicide is required, Aviator 235Xproapplied pre-Christmas is the best option to control Phoma, light leaf spot and mildew in crops, in one application.

Aviator 235Xpro contains the strongest azole (prothioconazole) plus the SDHI bixafen, offering good resistance management on top of excellent disease control. The Xpro formulation also offers improved leaf coverage and rain fastness within minutes of application.

Now that temperatures have dropped going into December, propyzamide applications will soon be made to crops with grassweed challenges. Where timings coincide, Aviator 235Xpro can be applied in tank mix with propyzamide.


Priorities now:

  • Monitor crops for Phoma and light leaf spot
  • Use SpotCheck to identify any early Light leaf spot in crops
  • Check soil temperatures for propyzamide application timing


What’s happening in oilseed rape in November

Oilseed rape crops are looking good, having established well across most growing areas, with plenty of moisture to aid early growth.

However there has also been plenty of Cabbage Stem Flea Beetle (CSFB) activity too, and increasingly further north in England. Activity will continue until temperatures drop below three degrees Centigrade.

The main focus of activity in OSR crops this month will be disease control. By the end of October, there had been little fungicide applied, and Phoma stem cankerhas been slow to express itself in crops this autumn.

The low levels of Phoma may be genetically-driven, with modern varieties increasingly having strong Phoma resistance ratings. More forward crops are also at lower risk. However, crops should still be monitored for signs of disease, since continued mild and wet weather provides ideal conditions for disease infection. Backwards crops in particular, are at higher risk.

Crops should be sprayed for Phoma once thresholds are reached, which for varieties with a Phoma rating of 6 or less, is 10% of plants affected. Where plants that are larger, or varieties have a Phoma rating above 6, the threshold is 20% of plants affected.

Light leaf spot risk will be higher where crops were drilled earlier. Bayer’s SpotCheck service is now open to receive leaf samples for disease presence identification. This year, sample packs can be applied for on our website, with the results emailed to you within seven working days.

Where growers are planning to spray only once before Christmas, using a fungicide which controls both Phoma and Light leaf spot gives more robust protection to the crop. Aviator 235Xpro contains the strongest azole (prothioconazole) plus the SDHI bixafen, offering good resistance management on top of excellent disease control. The Xpro formulation also offers improved leaf coverage and rain fastness within minutes of application.

Any remaining barley volunteers and grassweeds can be controlled once soils temperatures drop to below 10 degrees Centigrade at 30cm depth, where applications of propyzamide will be effective. Aviator may be used in tank mix with propyzamide if spray timings coincide.


Priorities now:

  • Monitor crops for Phoma and light leaf spot
  • Use SpotCheck to identify any early Light leaf spot in crops
  • Check soil temperatures for propyzamide application timing


What’s happening in oilseed rape in October

Oilseed rape crops are a mixed bag depending on when they were drilled, and what level of challenge they have faced from Cabbage Stem Flea Beetle (CSFB). The state of the crop will dictate to a certain extent the likely disease threat as they approach mid-autumn.

Crops that were drilled into moisture in August have grown away well, especially in the north and west, and some may even require some management before winter, to prevent them getting too forward.

The protracted harvest caused difficulties, especially in the east, and these crops went in later, to drying soils. Crops that have struggled to establish well due to lack of moisture have been under attack from CSFB.

The risk of Phoma stem canker will be lower in crops which are more forward, due to a greater leaf area, but crops with smaller canopies and varieties with lower resistance ratings will need close monitoring, especially if the weather turns wet.

Crops may need to be sprayed if disease levels reach thresholds, which for varieties with a Phoma rating of 6 or less, is 10% of plants affected. Where plants that are larger, or varieties have a Phoma rating above 6, the threshold is 20% of plants affected.

Phoma will usually show its symptoms before Light Leaf Spot. Downy mildew can cause similar looking bleached lesions to Phoma, but will typically show sporulating fungal growth on the underside of the leaf. The risk of Light Leaf Spot infection increases the longer the crop is in the ground, meaning earlier-drilled crops are at greater threat from disease. There is no threshold for spraying for Light Leaf Spot and fungicides only have protectant activity, so it is important to spray at the first sign of disease.

Bayer’s SpotCheck initiative picked up Light Leaf Spot much earlier in 2020 than in previous seasons. Infections identified in November came from earlier-drilled crops, so growers should be aware of the heightened risk and monitor crops regularly. SpotCheck will start in October for the 2021/22 season, accepting leaf samples to assess for signs of Light Leaf Spot, to help growers identify disease and justify spray decisions.

When sprays are applied from October onwards it is worth applying a fungicide that targets both Phoma and Light Leaf Spot, especially if it is unlikely that sprayers will be able to get back onto fields later in the winter.

Aviator is now available to use in oilseed rape in the autumn. Containing prothioconazole and bixafen, Aviator has excellent activity on Phoma, Light Leaf Spot, and Mildew. And, with two modes of action Aviator supports the best resistance management strategy.

A maximum of two applications of Aviator can be made to the crop, at maximum 1 l/ha rate. This allows both an autumn and spring spray, giving excellent protection to the crop over the highest risk period. The Xpro formulation also ensures improved coverage across the leaf and rain fastness within minutes of application, which helps with short spray windows and changeable weather.


Priorities now:

  • Monitor crops for Phoma and Light Leaf Spot spray if thresholds are reached
  • Use SpotCheck to identify any early Light Leaf Spot in crops
  • If an autumn spray is justified, use a robust autumn fungicide to protect crops through to the new year


What’s happening in oilseed rape in September

Many crops were drilled in August into relatively good, moist seedbeds, particularly across the south, with crops establishing well. Those further north, or where combining operations have been delayed due to poor weather, may still be drilling oilseed rape into September.

There are advantages to drilling in September, notably the reduction in disease pressure from light leaf spot. Where crops are drilled into good soil conditions later-drilled crops can still grow away well and often experience reduced larvae damage in the spring.

The downside is that September-drilled crops may require greater attention to disease control with Phoma stem canker coming in earlier than light leaf spot in the autumn, and crops with smaller leaf areas will be at higher risk, particularly during periods of wet weather. Poorly-established August-drilled crops may also be affected.

Growers should be mindful of their variety resistance scores and monitor crops closely for signs of disease, especially those with low Phoma resistance scores.

When it comes to managing CSFB, evidence of adult beetles feeding on young plants doesn’t necessarily always equate to yield loss.  The impact on yield will depend on the extent of the feeding and whether the growing point is damaged. If a spray is considered to control adult beetles, ensure thresholds are met. This means 25% of leaf area lost at the 1-2 leaf stage, or 50% leaf area lost at the 3-4 leaf stage.

Pyrethroid resistance is common throughout the UK, so growers should consider carefully whether a spray is warranted. Risk assess the crop and monitor the efficacy of the initial spray. If there is no reduction in feeding, there is likely to be resistance in the beetle population, so don’t spray again

Hybrid varieties offer the vigorous, fast growth required in the autumn when drilling in September, and offer strong spring growth too. Dekalb hybrids also offer excellent resistance to Phoma and light leaf spot.

Reducing competition from weeds will also help to support good crop establishment. Make weed-control decisions on a field-by-field basis depending on weed pressure, and aim to take out any fast-growing weeds and volunteer cereals in the autumn rather than leaving it until the spring.


Priorities now:

  • Ensure crops are drilled into good quality seed beds with moist soil for optimal establishment
  • Monitor crops for signs of Phoma, especially during wet periods
  • Monitor CSFB feeding damage and risk-assess crops before spraying

June and July

What’s happening in oilseed rape in June and July

It has been a difficult season for some growers with a wide range of crop quality. Some crops are looking excellent, while others are looking poor, particularly those that struggled to get established in the autumn.

At the beginning of June many crops are still in flower due to the cool weather in April and May. However, warmer temperatures in the first week of the month will hasten petal fall and crops are expected to catch up over the next few weeks.

The correct timing of desiccation sprays will be challenging with variation in growth stages within individual fields. Growers should carefully walk crops and assess the whole field, not just the headlands.

Taking seed samples from the area of the plant where most yield is being held will give the most accurate indication of spray timing. Where crops have not branched well, either due to flea beetle damage or high seed rates, most of the yield will be held on pods on the raceme. Conversely, where plants are well structured most of the yield will come from the side branches.

Take around 20 pods from different plants to assess ripeness. When the majority of the seed in the sample has turned from green to brown the crop has reached the 30% spray threshold for desiccation. Spraying too early can reduce oil content and increase the quantity of red seed due to immaturity at desiccation.

All Dekalb varieties have genetic pod shatter resistance, which gives some flexibility with desiccation timings, but many other varieties do not. Where pod shatter is a risk, consider applying a pod sealant to provide some security when waiting for full desiccation.

When choosing your desiccant, consider harvest intervals and use a premium formulation to encourage fast uptake of the active. All of the products from the Roundup portfolio have premium formulations and will provide quick update, while also providing the opportunity to take out any lingering weeds within the crop, before combining.


Priorities now:

  • Assess crop stand to identify where most of the yield is being held on the plants
  • Take seed samples regularly to correctly time desiccation sprays
  • Consider a pod sealant if variety lacks pod shatter resistance



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