Get more from your OSR

We know growing OSR can be stressful.  From establishing the crop at a busy time on farm, to concerns over pest attacks, right up until harvest with uncertainties over yield – it certainly has its challenges. Yet it’s still largely recognised as the most viable and profitable break crop, so we’ve teamed up with ADAS and other industry experts to help try and take some of that stress away.

Sign up to OSR Profitability to receive timely reminders on what to look out for and what action you should take, straight to your inbox, including findings from our three ADAS monitoring sites and sclerotinia project in our OSR Profitability Live technical updates. Plus receive 4 BASIS and 2 NRoSO points!

But that’s not all. In addition, also look out for our:

  • Joint ADAS & BASF OSR calendar for clear, straight forward advice on key topics by month
  • Useful resource centre with insight from our experts
  • Innovative support tools such as our lodging calculator and GAI tool.

The OSR State of the Nation Survey

The OSR State of the Nation Survey The results are in. 68% of farmers say is their most profitable break crop. We wanted to shed some light on what’s really going on in OSR fields up and down the country in the UK’s biggest OSR survey.

See the results
Explore the map to find out more about our monitoring sites.

Get expert advice direct from the experts

Our panel of OSR experts will be providing advice and tips on how to get the most out of your crop throughout the season, whether as part of our OSR Profitability Live technical updates, our OSR calendar or informative blog posts. Sign up to OSR Profitability to get priority alerts on all their latest insights.

OSR Resource Centre

Browse our library for advice and expertise on a range of OSR key topics, giving you the insight to get the most from your crop.

Find out more

OSR Calendar

Find out more about the key issues to look out for each month, why they’re important and how you can control them.

  • jan
  • feb
  • mar
  • apr
  • may
  • jun
  • jul
  • aug
  • sep
  • oct
  • nov
  • dec
  • jan
  • feb
  • mar
  • apr
  • may
  • jun
  • jul
  • aug
  • sep
  • oct
  • nov
  • dec
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January

Light leaf spot

Description

Early symptoms difficult to spot, particularly on wet crops. White spore masses appear first, like tiny grains of salt on the leaf. Pale green lesions develop, later taking on a mealy appearance without a defined edge and can be confused with frost damage or scorch. Plant stunting and leaf distortion can occur and heavily infected plants may be killed during cold frosty weather.

Importance

Now considered the most economically damaging OSR disease in the UK. Yield losses of 0.75 t/ha have been observed and losses of >50% can occur when plants are killed during winter.

Action

Check crops for symptoms. Re-infection may have occurred, particularly if a second phoma spray was not applied or if fields were too wet to travel in December. Collect and incubate leaves to facilitate the expression of symptoms. Apply fungicide with activity against LLS as soon as fresh symptoms are seen. Check the LLS risk in your area.

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February

Light leaf spot

Description

Leaf lesions have a mealy appearance without a defined edge and can sometimes be confused with frost damage or scorch. Tiny white spore masses are often present around the edge of the lesion but might not be obvious if recent rain has washed them off. Plant stunting and leaf distortion can occur and heavily infected plants may be killed during cold frosty weather.

Importance

Now considered the most economically damaging OSR disease in the UK. Yield losses of 0.75 t/ha have been observed and losses of >50% can occur when plants are killed during winter.

Action

Check youngest leaves for new symptoms. The latent period is approximately 30 days at mean daily temperature of 4oC. Collect and incubate leaves to facilitate the expression of symptoms. Apply fungicide with activity against LLS as soon as fresh symptoms seen or at early stem extension, choose a fungicide with PGR activity if canopy is large. Check the LLS risk in your area.

/
February

Spring canopy management

Description

Canopy management involves managing the canopy throughout the autumn and spring to achieve a green area index (GAI) of 3.5 units at flowering. A canopy with a GAI of 3.5 units will have 3.5 metre squared of green tissue per metre squared of ground.

Importance

Achieving a GAI of 3.5 at flowering maximizes the crop’s yield potential by enabling it to set lots of seeds after flowering and by minimizing the risk of lodging.

Action

Measure GAI during February. GAI can be assessed by eye, by phone or web apps, or by cutting all the crop from 1 m2 ground, measuring the fresh weight (in kg) and multiplying by 0.8. The latter method is most appropriate for crops with large GAIs of 3 or above.

PGRs: Crops with a GAI measured before, or at the point of stem extension, would be expected to increase yield in response to a PGR. PGRs can be applied between the start of stem extension and early flowering depending on the PGR product.

/
February

Nutrition

Description

The optimum canopy size of GAI 3 to 4 at flowering can be achieved through careful N fertiliser management. Oilseed rape must take up 50 kg N/ha to build each unit of GAI, so a crop with an optimum sized canopy of GAI 3.5 at flowering contains 175 kg N/ha.

Importance

N fertilizer usually gives the greatest yield increase of any input, typically about 2 t/ha. Sulphur also usually gives a yield increase, and is essential now that little S is deposited from the atmosphere.

Action

Soil Nitrogen Supply (SNS):Estimate using either the Field Assessment Method (FAM) described in RB209 or by measuring Soil Mineral Nitrogen (SMN) and crop N.

Estimating crop N: This can be determined by observation of the canopy size (GAI) since each GAI unit contains about 50 kg N/ha, or 40-50 kg N/ha for crops with GAI of 2 or more.

Fertiliser N recovery: Fertiliser N is only taken up with an apparent efficiency of 60%; N already present in the soil (SNS) is taken up with an apparent efficiency of 100%.

Adjustment for high expected yield: Crops with an expected yield in excess of 3.5 t/ha require additional N. Each 0.5 t/ha yield over 3.5 t/ha (up to a maximum of 5 t/ha) needs an additional 30 kg/ha fertiliser N.

N Timings:If the GAI is less than 1.5, or less than 2.0 with an SMN in the top 60 cm soil of less than 25 kg N/ha, apply the nitrogen in two equal splits at the start of spring growth (end February-early March) and green bud (mid-March – early April). Additional nitrogen for crops yielding above 3.5 t/ha should be applied between yellow bud and early flowering.  Where the GAI is greater than 2.0, or greater than 1.5 with an SMN in the top 60 cm soil of at least 25 kg N/ha, then the first nitrogen should be reduced to between zero and 40 kg N/ha.

Sulphur: Rates of 50 to 75 kg SO3/ha are almost always sufficient to rectify even the most S deficient conditions. Slight or moderate sulphur deficiencies can be rectified by sulphur applications up to the late green bud stage.

/
March

Light leaf spot

Description

Leaf lesions have a mealy appearance without a defined edge and can sometimes be confused with frost damage or scorch. Tiny white spore masses are often present around the edge of the lesion. Plant stunting and leaf distortion can occur and severely affected plants show weak stem extension growth. Flower buds may also show symptoms or be distorted.

Importance

Now considered the most economically damaging OSR disease in the UK. Yield losses of 0.75 t/ha have been observed and losses of >50% can occur when plants are killed during winter.

Action

Check youngest leaves, stems and flower buds for new symptoms. The latent period is approximately 30 days at mean daily temperature of 4oC.  Apply fungicide with activity against LLS as soon as fresh symptoms seen or at early stem extension.  Choose a fungicide with PGR activity if canopy is large. Check the LLS risk in your area.

/
March

Clubroot

Description

Encouraged by short rotations and acidic, warm (>16°C), wet soils. Galls are formed on OSR roots which impair normal root function, reducing water and nutrient uptake. Symptoms include poor crop establishment, poor growth and stunting. Severely affected plants can be killed completely. A second phase of clubroot may occur in spring.

Importance

Incidence has increased in recent years, particularly where oilseed rape or other susceptible crops have been grown on short rotation. Yield loss has been quantified as 0.3 t/ha for every 10% plants affected and complete crop loss can occur when severe.

Action

Check for signs of new or increased infection. Often occurs in patches so pull plants and inspect roots from across the whole field. Severely affected crops are sometimes re-drilled. Spring oilseed rape is also susceptible to clubroot so choose a suitable alternative crop if problems persist. Advice for sowing as per August.

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March

Spring weed control

Description

Weeds that have escaped control in the autumn and winter can be treated in the spring, namely cleavers, thistles and mayweed.

Importance

Weeds, particularly cleavers can compete directly with and smother the crop, increasing the risk of seed contamination.

Action

Clopyralid and/or picloram can be applied from 1st March to flower buds visible above the crop canopy. Apply when air temperatures are 6°C and rising and weeds less than 15cm in size.

/
March

Spring canopy management

Description

Canopy management involves managing the canopy throughout the autumn and spring to achieve a green area index (GAI) of 3.5 units at flowering. A canopy with a GAI of 3.5 units will have 3.5 metre squared of green tissue per metre squared of ground.

Importance

Achieving a GAI of 3.5 at flowering maximizes the crop’s yield potential by enabling it to set lots of seeds after flowering and by minimizing the risk of lodging.

Action

Measure GAI during February. GAI can be assessed by eye, by phone or web apps, or by cutting all the crop from 1 m2 ground, measuring the fresh weight (in kg) and multiplying by 0.8. The latter method is most appropriate for crops with large GAIs of 3 or above.

PGRs: Crops with a GAI measured before, or at the point of stem extension, would be expected to increase yield in response to a PGR. PGRs can be applied between the start of stem extension and early flowering depending on the PGR product.

/
March

Nutrition

Description

The optimum canopy size of GAI 3 to 4 at flowering can be achieved through careful N fertiliser management. Oilseed rape must take up 50 kg N/ha to build each unit of GAI, so a crop with an optimum sized canopy of GAI 3.5 at flowering contains 175 kg N/ha.

Importance

N fertilizer usually gives the greatest yield increase of any input, typically about 2 t/ha. Sulphur also usually gives a yield increase, and is essential now that little S is deposited from the atmosphere.

Action

Soil Nitrogen Supply (SNS):Estimate using either the Field Assessment Method (FAM) described in RB209 or by measuring Soil Mineral Nitrogen (SMN) and crop N.

Estimating crop N: This can be determined by observation of the canopy size (GAI) since each GAI unit contains about 50 kg N/ha, or 40-50 kg N/ha for crops with GAI of 2 or more.

Fertiliser N recovery: Fertiliser N is only taken up with an apparent efficiency of 60%; N already present in the soil (SNS) is taken up with an apparent efficiency of 100%.

Adjustment for high expected yield: Crops with an expected yield in excess of 3.5 t/ha require additional N. Each 0.5 t/ha yield over 3.5 t/ha (up to a maximum of 5 t/ha) needs an additional 30 kg/ha fertiliser N.

N Timings:If the GAI is less than 1.5, or less than 2.0 with an SMN in the top 60 cm soil of less than 25 kg N/ha, apply the nitrogen in two equal splits at the start of spring growth (end February-early March) and green bud (mid-March – early April). Additional nitrogen for crops yielding above 3.5 t/ha should be applied between yellow bud and early flowering.  Where the GAI is greater than 2.0, or greater than 1.5 with an SMN in the top 60 cm soil of at least 25 kg N/ha, then the first nitrogen should be reduced to between zero and 40 kg N/ha.

Sulphur: Rates of 50 to 75 kg SO3/ha are almost always sufficient to rectify even the most S deficient conditions. Slight or moderate sulphur deficiencies can be rectified by sulphur applications up to the late green bud stage.

/
April

Stem rot (Sclerotinia)

Description

Fawn coloured leaf lesions often form around petals. White stem lesions develop, gradually encircling the stem. Fluffy white mycelium, which look like cotton wool, may be present and hard black sclerotia, which look like rat droppings, form inside the stem. Severe lesions on the main stem lead to plant death and premature ripening of pods.

Importance

Yield losses >50% or >2 t/ha can occur in severely affected crops and a severe epidemic is reported in the UK approximately every 7-8 years. Yield loss is estimated as 0.6% for each 1% plants with main stems affected. Sclerotinia affects a wide range of broad-leaved crops and weeds and its importance should be considered for the whole rotation because of its persistence in the soil.

Action

Use decision support tools (AHDB and BASF), previous farm history, local weather and crop flowering stage to assess risk. Apply fungicides at early-mid flower (GS 4.3 – 4.5). Treatments need to be protectant and fungicides offer approximately 3 weeks protection at high rates (minimum ¾ of the recommended label dose for most products).

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April

Green leaf area & duration (GLAD)

Description

Healthy, large and plentiful leaves, retained for a long time, increase yield. The photosynthetic capacity of OSR leaves is twice as high as for stems or pods. Green leaves are lost rapidly from the start of flowering through to green seed.

Importance

Maximising the size and duration of green leaf area (GLAD) increases the crop’s yield potential by enabling it to set lots of seeds during the 2-3 weeks after flowering and then to subsequently fill the seeds. Yield increases of 0.04 t/ha have been observed for each additional unit of GLAD, particularly where sunshine is limited during the critical summer months.

Action

Apply fungicides as necessary during flowering to protect against disease and prevent the loss of green leaf area. Where possible, choose products which are known to have additional benefits to the crop such as greening effects, effects on the canopy and improvements to water use efficiency.

/
April

Pollen beetle

Description

Black shiny beetles in crops from March onwards.  Can cause bud loss, blind stalks and yield loss.  Adults lay eggs in buds and larvae, creamy white with a black head and six legs, feed on pollen.

Importance

OSR susceptible at the green/yellow bud stage.  Spring crops more vulnerable than winter, as susceptible stage coincides with migration.  Increased branching can offset loss of buds.

Action

Monitor crops at susceptible stage when dry and warm (>15oC).  Use pollen beetle predictor to indicate when migration has started.  Thresholds dependent on plant population:

  • < 30 plants/m2 – 25 beetles/plant
  • 30–50 plants/m2 – 18 beetles/plant
  • 50–70 plants/m2 – 11 beetles/plant
  • > 70 plants/m2 – 7 beetles/plant

Only spray if thresholds exceeded and consider alternative products.

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April

Light leaf spot

Description

Leaf lesions have a mealy appearance without a defined edge and spores often present around the edge of the lesion if weather is conducive for sporulation. Stunting, leaf distortion and flowering problems can occur in severely affected crops. Stems may show signs of cracking and lesions appear with black speckling around the edges with a less sharply defined margin than phoma

Importance

Now considered the most economically damaging OSR disease in the UK. Yield losses of 0.75 t/ha have been observed and losses of >50% can occur when plants are killed during winter.

Action

Check leaves, stems and flower buds for symptoms and note progress up the canopy. Further treatment may be required to protect the pods if the disease is still active at flowering. Sclerotinia sprays may be selected carefully to offer protection against LLS too.

/
April

Spring canopy management

Description

Canopy management involves managing the canopy throughout the autumn and spring to achieve a green area index (GAI) of 3.5 units at flowering. A canopy with a GAI of 3.5 units will have 3.5 metre squared of green tissue per metre squared of ground.

Importance

Achieving a GAI of 3.5 at flowering maximizes the crop’s yield potential by enabling it to set lots of seeds after flowering and by minimizing the risk of lodging.

Action

Measure GAI during February. GAI can be assessed by eye, by phone or web apps, or by cutting all the crop from 1 m2 ground, measuring the fresh weight (in kg) and multiplying by 0.8. The latter method is most appropriate for crops with large GAIs of 3 or above.

PGRs: Crops with a GAI measured before, or at the point of stem extension, would be expected to increase yield in response to a PGR. PGRs can be applied between the start of stem extension and early flowering depending on the PGR product.

/
April

Nutrition

Description

The optimum canopy size of GAI 3 to 4 at flowering can be achieved through careful N fertiliser management. Oilseed rape must take up 50 kg N/ha to build each unit of GAI, so a crop with an optimum sized canopy of GAI 3.5 at flowering contains 175 kg N/ha.

Importance

N fertilizer usually gives the greatest yield increase of any input, typically about 2 t/ha. Sulphur also usually gives a yield increase, and is essential now that little S is deposited from the atmosphere.

Action

Soil Nitrogen Supply (SNS):Estimate using either the Field Assessment Method (FAM) described in RB209 or by measuring Soil Mineral Nitrogen (SMN) and crop N.

Estimating crop N: This can be determined by observation of the canopy size (GAI) since each GAI unit contains about 50 kg N/ha, or 40-50 kg N/ha for crops with GAI of 2 or more.

Fertiliser N recovery: Fertiliser N is only taken up with an apparent efficiency of 60%; N already present in the soil (SNS) is taken up with an apparent efficiency of 100%.

Adjustment for high expected yield: Crops with an expected yield in excess of 3.5 t/ha require additional N. Each 0.5 t/ha yield over 3.5 t/ha (up to a maximum of 5 t/ha) needs an additional 30 kg/ha fertiliser N.

N Timings:If the GAI is less than 1.5, or less than 2.0 with an SMN in the top 60 cm soil of less than 25 kg N/ha, apply the nitrogen in two equal splits at the start of spring growth (end February-early March) and green bud (mid-March – early April). Additional nitrogen for crops yielding above 3.5 t/ha should be applied between yellow bud and early flowering.  Where the GAI is greater than 2.0, or greater than 1.5 with an SMN in the top 60 cm soil of at least 25 kg N/ha, then the first nitrogen should be reduced to between zero and 40 kg N/ha.

Sulphur: Rates of 50 to 75 kg SO3/ha are almost always sufficient to rectify even the most S deficient conditions. Slight or moderate sulphur deficiencies can be rectified by sulphur applications up to the late green bud stage.

/
May

Stem rot (Sclerotinia)

Description

Fawn coloured leaf lesions often form around petals. White stem lesions develop, gradually encircling the stem. Fluffy white mycelium, which look like cotton wool, may be present and hard black sclerotia, which look like rat droppings, form inside the stem. Severe lesions on the main stem lead to plant death and premature ripening of pods.

Importance

Yield losses >50% or >2 t/ha can occur in severely affected crops and a severe epidemic is reported in the UK approximately every 7-8 years. Yield loss is estimated as 0.6% for each 1% plants with main stems affected. Sclerotinia affects a wide range of broad-leaved crops and weeds and its importance should be considered for the whole rotation because of its persistence in the soil.

Action

Continue to assess risk by using decision support tools (AHDB and BASF), previous farm history, local weather and crop flowering stage. If flowering is prolonged and risk is moderate or high, apply a second sclerotinia fungicide approximately 2.5 – 3 weeks after the first spray.

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May

Green leaf area & duration (GLAD)

Description

Healthy, large and plentiful leaves, retained for a long time, increase yield. The photosynthetic capacity of OSR leaves is twice as high as for stems or pods. Green leaves are lost rapidly from the start of flowering through to green seed.

Importance

Maximising the size and duration of green leaf area (GLAD) increases the crop’s yield potential by enabling it to set lots of seeds during the 2-3 weeks after flowering and then to subsequently fill the seeds. Yield increases of 0.04 t/ha have been observed for each additional unit of GLAD, particularly where sunshine is limited during the critical summer months.

Action

Apply fungicides as necessary during flowering to protect against disease and prevent the loss of green leaf area. Where possible, choose products which are known to have additional benefits to the crop such as greening effects, effects on the canopy and improvements to water use efficiency.

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May

Light leaf spot

Description

Leaf lesions have a mealy appearance without a defined edge. Stunting, leaf distortion and flowering problems can occur in severely affected crops. Stems may show signs of cracking and lesions appear with black speckling around the edges with a less sharply defined margin than phoma. Pods may be curled and distorted with pinkish brown discolouration or carry lesions with black speckling and producing white spore pustules.

Importance

Now considered the most economically damaging OSR disease in the UK. Yield losses of 0.75 t/ha have been observed and losses of >50% can occur when plants are killed during winter.

Action

Check leaves, stems, remaining flower buds and early pods for symptoms and note progress up the canopy. Further treatment may be required to protect the pods if the disease is still active at flowering. Sclerotinia sprays may be selected carefully to offer protection against LLS too.

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June

Stem rot (Sclerotinia)

Description

White stem lesions develop, gradually encircling the stem. Fluffy white mycelium, which look like cotton wool, may be present and hard black sclerotia, which look like rat droppings, form inside the stem. Severe lesions on the main stem lead to plant death, lodging and premature ripening of pods.

Importance

Yield losses >50% or >2 t/ha can occur in severely affected crops and a severe epidemic is reported in the UK approximately every 7-8 years. Yield loss is estimated as 0.6% for each 1% plants with main stems affected. Sclerotinia affects a wide range of broad-leaved crops and weeds and its importance should be considered for the whole rotation because of its persistence in the soil.

Action

The risk period for sclerotinia infection is now over but plant-to-plant infection can occur, particularly if crops are starting to lodge. No further fungicide treatment is recommended but consider incorporating a bio-control agent such Contans into the soil prior to drilling, to break down sclerotia after a bad attack.

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June

Light leaf spot

Description

Stems may show signs of cracking and lesions appear with black speckling around the edges with a less sharply defined margin than phoma. Pods may be curled and distorted with pinkish brown discolouration or carry lesions with black speckling and producing white spore pustules. Pods may peel and ripen prematurely.

Importance

Now considered the most economically damaging OSR disease in the UK. Yield losses of 0.75 t/ha have been observed and losses of >50% can occur when plants are killed during winter.

Action

Check stems and pods for LLS symptoms. Further treatment is not recommended at this stage but it is useful to note final levels of disease in the crop because infected debris will form the inoculum source for the epidemic in the following season.

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June

Clubroot

Description

Galls are formed on OSR roots which impair normal root function, reducing water and nutrient uptake. Above ground symptoms include poor crop establishment, poor growth and stunting. Severely affected plants can be killed completely. A second phase of clubroot may occur in spring and wilting may occur during warm dry weather. The crop may lodge due to poor root development.

Importance

Incidence has increased in recent years, particularly where oilseed rape or other susceptible crops have been grown on short rotation. Yield loss has been quantified as 0.3 t/ha for every 10% plants affected and complete crop loss can occur when severe.

Action

Check the crop for final clubroot levels and use the information to guide variety and rotation choices for next season. Take a soil sample from the field to check pH, calcium and boron status.

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July

Clubroot

Description

Galls are formed on OSR roots which impair normal root function, reducing water and nutrient uptake. Above ground symptoms include poor crop establishment, poor growth and stunting. Severely affected plants can be killed completely. A second phase of clubroot may occur in spring and wilting may occur during warm dry weather. The crop may lodge due to poor root development.

Importance

Incidence has increased in recent years, particularly where oilseed rape or other susceptible crops have been grown on short rotation. Yield loss has been quantified as 0.3 t/ha for every 10% plants affected and complete crop loss can occur when severe.

Action

Check the crop for final clubroot levels and use the information to guide variety and rotation choices for next season. Take a soil sample from the field to check pH, calcium and boron status.

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August

Cabbage stem flea beetle

Description

Adults are 3-4.5mm long, blue-black or light brown.  Adult and larval stages damage OSR crops.  Sometimes seen on top of trailer loads at harvest and crushers may reject contaminated seed.

Importance

Adults can reduce green leaf area, kill seedlings and cause crop failure.  Hatching larvae in the soil bore into leaf petioles to feed, then later the main stem.  Rapidly growing crops vital to combat csfb.

Action

Seed source: Don’t sow low TSW seed if conditions for establishment are poor.

Cultivations: Good seed beds vital to maximise seed-soil contact and help combat slugs.

Variety choice: Choose varieties that establish quickly and have early vigour.

Sowing date: Drill mid-August to mid-September.  Drill when seed beds are moist.

Seed rate: The optimal plant population of 25-35 plants/m2 can be achieved from 30-40 seeds/m2.

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August

Early weed control

Description

Most OSR weeds germinate in late summer and early autumn.  Weeds such as crane’s-bill and shepherds purse are best controlled using a pre-emergence herbicide based on metazachlor and dimethenamid-P, such as Springbok, whilst quinmerac increases control of poppy and cleavers.

Importance

As the crop emerges it’s small and uncompetitive, further hindered by dry seedbeds, csfb and slugs. A pre-emergence herbicide will remove competition from emerging weeds, giving the crop the best chance of establishment.

Action

Herbicide: Base on expected weed burden

Metazachlor restrictions: Note maximum dose is 750g a.i/ha and 1000g a.i/ha over 3 years

Soil cover: Ensure seed covered by the at least 15mm of settled soil to prevent damage

Timing: Apply pre-emergence herbicides within 24-48 hours of drilling, or delay until cotyledons are fully expanded. DO NOT apply when the seed is chitting.

Stewardship: Minimise movement of herbicides to water by avoiding application after 30th September and be aware of the stewardship for metazachlor and quinmerac. For more information click here

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August

Light leaf spot

Description

Affects leaves, stems and pods and initiated from airborne ascospores in autumn. Leaf symptoms are mealy white lesions with tiny white spore droplets around the edge. Secondary spread occurs by means of rain-splash. The disease is polycyclic and infection can continue throughout the season.

Importance

Endemic across the UK and >85% of OSR have been reported to show symptoms. Yield losses of 0.75 t/ha have been observed and losses of >50% can occur when plants are killed during winter. Yield loss estimated as 33% x % plants affected at early stem extension (i.e., if 15% plants are affected the yield loss would be approximately 5%).

Action

Choose a resistant variety if light leaf spot is a problem on your farm. Bury infected crop residue and avoid early sowing.

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August

Clubroot

Description

Encouraged by short rotations and acidic, warm (>16°C), wet soils. Galls are formed on OSR roots which impair normal root function, reducing water and nutrient uptake. Symptoms include poor crop establishment, poor growth and stunting. Severely affected plants can be killed completely.

Importance

Incidence has increased in recent years, particularly where oilseed rape or other susceptible crops have been grown on short rotation. Yield loss has been quantified as 0.3 t/ha for every 10% plants affected and complete crop loss can occur when severe.

Action

Test soil: Commercial testing available through SRCU and PGRO.

Variety choice: Sow a resistant variety.

Management: Increase soil pH to at least 7, correct any soil boron deficiencies prior to sowing and avoid early sowing. Remedy drainage problems and minimise soil movement on farm equipment. Extend rotation on known infected land to at least four years between brassica crops.

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August

Establishment

Description

The optimal plant population is 25-35 plants/m2, which can usually be achieved from 30-40 seeds/m2.  Heavier seed rates may be required if the seedbed is cloddy, straw spreading is uneven, or there is a risk of seedling predation by slugs or/and CSFB.

Importance

Establishing too few plants reduces yield potential, but it is often surprising how much yield low plant populations can produce with 10 plants/m2 shown to produce more than 3 t/ha. Establishing too many plants reduces yield potential due to the greater risk of producing a super-optimal canopy size at flowering (which reduces seed set in the pods) and increases the risk of lodging.

Action

Aim to sow enough seeds to achieve 25-35 plants/m2 after taking account of the effect of seed bed conditions and the risk of slugs and CSFB.

 

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September

Cabbage stem flea beetle

Description

Adult feeding causes ‘shot-holes’ which reduce green leaf area.  Slugs cause similar damage but usually accompanied by slime trails.

Importance

Adults kill plants if growing points destroyed as they emerge.  Once above ground, seedlings tolerate some damage and shot-holes need not mean yield loss.  Damage intensifies in dry conditions.

Action

Only pyrethroids are approved against adult csfb.  Resistance is relatively common so sprays only advised if thresholds exceed:

  • Cotyledon to 2 TL stage – 25% or more of leaf area lost
  • 3 – 4 TL stage – 50% or more of leaf area lost.
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September

Slugs

Description

Grey field slug most damaging until 4 TL stage, notably in heavy soils, organic matter, warmth and moisture.  Optimum temperature 17°C but active between 5°C and 20°C.

Importance

Most damaging to seedlings, causing yield loss and even crop failure, especially where growth is slow.

Action

Cultural control

  • Soil cultivation reduces slug numbers
  • Stubble rakes can reduce slug pressure
  • Good seed beds speed up establishment

Chemical control

  • Monitor activity with refuge traps
  • One slug per trap justifies treatment
  • Only apply pellets if slugs active
  • Consider ferric phosphate in Drinking Water Protected Area or Safeguard Zone.
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September

Autumn canopy management

Description

Canopies should be managed to achieve a green area index (GAI) of 3.5 units at flowering – 3.5 metre squared of green tissue per metre squared of ground.

Importance

Achieving a GAI of 3.5 at flowering maximizes the crop’s yield potential by enabling it to set lots of seeds after flowering and minimizes lodging risk.

Action

Variety choice: If sowing late (after early September), opt for a variety with good early vigour.

Seed rate: The optimal plant population of 25-35 plants/m2 can be achieved from 30-40 seeds/m2.  Consider higher rates if seed bed is cloddy, straw spreading is uneven, or high risk of slugs or/and CSFB.

Autumn N: Beneficial, particularly in situations where the plant available soil N is low, such as where the crop has been direct drilled or large amounts of straw from the previous crop have been incorporated. Crops sown after early September less likely to respond to autumn N.

PGRs: Crops sown early in good conditions have a risk of producing large canopies before winter. Consider a PGR like Caryx in September or October to reduce excessive autumn growth.

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September

Light leaf spot

Description

Affects leaves, stems and pods and initiated from airborne ascospores in autumn. Leaf symptoms are mealy white lesions with tiny white spore droplets around the edge. Secondary spread occurs by means of rain-splash. The disease is polycyclic and infection can continue throughout the season.

Importance

Endemic across the UK and >85% of OSR have been reported to show symptoms. Yield losses of 0.75 t/ha have been observed and losses of >50% can occur when plants are killed during winter. Yield loss estimated as 33% x % plants affected at early stem extension (i.e., if 15% plants are affected the yield loss would be approximately 5%).

Action

Choose a resistant variety if light leaf spot is a problem on your farm. Bury infected crop residue and avoid early sowing.

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September

Volunteer & grass weed control

Description

Cereal volunteers from previous crop usually present unless the field has been ploughed. Many will have been removed by an application of glyphosate prior to drilling.  Black-grass, brome and wild oats may also be present.

Importance

Populations as low as 20 volunteers/m² can reduce yields by 0.15 t/ha and damage is done in the first few weeks of establishment. Delayed control will give little to no yield benefit as crop establishment never catches up and the risk of pigeon damage through the winter is increased.

Action

Timing: Target volunteers at optimum growth stage of 2 leaves

Dose rate: Increase where weeds are larger or in dry conditions

Applications: Only 2 fop/dim applications can be made to an OSR crop.

Herbicide: Use a product such as Laser and if a further flush appears, use an alternative.

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October

Brassica weed control

Description

Charlock, runch and hedge mustard are challenging to control in OSR. Clearfield varieties, conventionally bred to tolerate imazamox, an effective brassica herbicide, enable control.

Importance

Brassicas emerge and grow faster than oilseed rape, competing with and smothering the crop in the autumn, followed by harvesting and seed quality problems.  Approximately 2-5% contamination can raise glucosinolate and erucic acid levels in harvested seed.

Action

Good records are the key to control of this weed in oilseed rape. Where field records indicate a previous problem with brassica weeds, grow a Clearfield variety and apply Cleranda or Cleravo at 1-4 true leaves of the weeds.

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October

Cabbage stem flea beetle

Description

Adult feeding causes ‘shot-holes’ which reduce green leaf area.  Slugs cause similar damage but usually accompanied by slime trails.

Importance

Adults kill plants if growing points destroyed as they emerge.  Once above ground, seedlings tolerate some damage and shot-holes need not mean yield loss.  Damage intensifies in dry conditions.

Action

Only pyrethroids are approved against adult csfb.  Resistance is relatively common so sprays only advised if thresholds exceed:

  • Cotyledon to 2 TL stage – 25% or more of leaf area lost
  • 3 – 4 TL stage – 50% or more of leaf area lost.
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October

Slugs

Description

Grey field slug most damaging until 4 TL stage, notably in heavy soils, organic matter, warmth and moisture.  Optimum temperature 17°C but active between 5°C and 20°C.

Importance

Most damaging to seedlings, causing yield loss and even crop failure, especially where growth is slow.

Action

Cultural control

  • Soil cultivation reduces slug numbers
  • Stubble rakes can reduce slug pressure
  • Good seed beds speed up establishment

Chemical control

  • Monitor activity with refuge traps
  • One slug per trap justifies treatment
  • Only apply pellets if slugs active
  • Consider ferric phosphate in Drinking Water Protected Area or Safeguard Zone.
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October

Autumn canopy management

Description

Canopy management involves managing the canopy throughout the autumn and spring to achieve a green area index (GAI) of 3.5 units at flowering. A canopy with a GAI of 3.5 units will have 3.5 metre squared of green tissue per metre squared of ground.

Importance

Achieving a GAI of 3.5 at flowering maximizes the crop’s yield potential by enabling it to set lots of seeds after flowering and by minimizing the risk of lodging.

Action

PGRs: Crops sown early in good conditions have a risk of producing large canopies of as much as 3 units of GAI before winter. To make these crops easier to manage in the spring, consider using a PGR in September or October to reduce excessive autumn growth.

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November

Light leaf spot

Description

Early symptoms difficult to spot, particularly on wet crops. White spore masses appear first, which look like tiny grains of salt and often on an otherwise green leaf. Pale green lesions develop, later taking on a mealy appearance without a defined edge and can be confused with frost damage or scorch.

Importance

Endemic across the UK. Yield losses of 0.75 t/ha have been observed and losses of >50% can occur when plants are killed during winter. Yield loss is estimated as 33% x % plants affected at early stem extension (i.e., if 15% plants are affected the yield loss would be approximately 5%).

Action

Check crops for symptoms. Often occurs in patches so walk the whole field. The first phoma spray offers a limited period of protection against LLS. Collect and incubate leaves to facilitate the expression of symptoms. Apply fungicide to target LLS as soon as symptoms are seen.

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November

Cabbage stem flea beetle

Description

Newly hatched larvae enter plants October – early April.  Mainly white, with black dots, six legs, black head and plate.  Feed in leaf petioles, then the stem.

Importance

Larval feeding reduces crop vigour and yield.  Crop tolerance depends on growth stage at egg hatch.  Autumn larvae more damaging than spring.

Action

  • Dissect plants in November to determine infestation
  • Spray with a pyrethroid only if the threshold of five larvae per plant is exceeded.
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November

Peach-potato aphid and TuYV

Description

Wingless, peach-potato aphids usually on underside of leaves and can be green, yellow or light red.  Migration from September – mid-November and later in mild years.  Symptoms include purple tingeing of leaf edges and pods, usually in late spring/early summer.

Importance

Peach-potato aphid main vector of TuYV.  Can cause yield loss up to 30% and greatest when young plants infested in autumn and high proportion of aphids carrying the virus.  The aphids are resistant to organophosphorus, carbamate and pyrethroid insecticides.

Action

Monitor crops for aphids using AHDB Aphid News for updates on pest migration.  If numbers are high, one autumn insecticide can be applied.  Migration usually ends mid-November.  If no aphids found, treatment unlikely to be needed.  Amalie is resistant to TuYV.

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November

Grass weed and poppy control

Description

As temperatures fall, OSR provides an opportunity to control black-grass and other grass weeds using propyzamide, a herbicide to which there is no known resistance. Laser can also provide additional grass weed and cereal volunteer control in a programme or as a tank mix

Importance

The role of propyzamide in the battle against black-grass is one of the main reasons oilseed rape is included in a rotation. Propyzamide has a different mode of action to other oilseed rape herbicides.

Action

Establishment: Use shallow cultivations to derive maximum control of weeds from propyzamide.

Conditions: Apply when soil temperatures at 30cm reach 10°C and are falling, and where there is sufficient moisture in the soil surface layer for plant uptake.

Applications: Note only 2 fop/dim applications can be made to an OSR crop.

Aminopyralid: Add to give good control of poppies and mayweed.

Stewardship: See propyzamide guidelines here.

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December

Clubroot

Description

Encouraged by short rotations and acidic, warm (>16°C), wet soils. Galls are formed on OSR roots which impair normal root function, reducing water and nutrient uptake. Symptoms include poor crop establishment, poor growth and stunting. Severely affected plants can be killed completely.

Importance

Incidence has increased in recent years, particularly where oilseed rape or other susceptible crops have been grown on short rotation. Yield loss has been quantified as 0.3 t/ha for every 10% plants affected and complete crop loss can occur when severe.

Action

Check for signs of infection. Often occurs in patches so pull plants and inspect roots from across the whole field. Remedy drainage problems and minimise soil movement on farm equipment to avoid further spread of the disease between fields. Minimise movement of manures, feed swedes and turnips (potentially infected with club root) onto clean land.

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December

Light leaf spot

Description

Early symptoms difficult to spot, particularly on wet crops. White spore masses appear first, like tiny grains of salt on the leaf. Pale green lesions develop, later taking on a mealy appearance without a defined edge and can be confused with frost damage or scorch. Plant stunting and leaf distortion can occur and heavily infected plants may be killed during cold frosty weather.

Importance

Now considered the most economically damaging OSR disease in the UK. Yield losses of 0.75 t/ha have been observed and losses of >50% can occur when plants are killed during winter.

Action

Check crops for symptoms. Often occurs in patches so walk the whole field. Collect and incubate leaves to facilitate the expression of symptoms. If a second phoma spray is not being applied, then target LLS as soon as symptoms are seen or by mid-December. Check the LLS risk in your area.

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