Oilseed rape (OSR) remains one of the UK's most valuable break crops, but successful establishment has become increasingly challenging due to pressure from cabbage stem flea beetle (CSFB), rising input costs and changing weather patterns. As a result, many growers are turning to companion crops for oilseed rape as part of an integrated pest management (IPM) strategy.
Companion cropping is no longer a niche practice. It is now widely recognised as an effective way to improve oilseed rape establishment, support biodiversity, enhance nutrient availability and reduce the impact of flea beetle during the crop's most vulnerable growth stages.
What Are Companion Crops for Oilseed Rape?
Companion crops are plants established alongside oilseed rape to provide agronomic benefits without competing significantly with the main crop.
Rather than growing OSR alone, growers sow carefully selected companion species that can:
- Help reduce cabbage stem flea beetle pressure
- Improve crop establishment
- Fix atmospheric nitrogen
- Improve soil structure
- Increase biodiversity
- Support beneficial insects
- Provide ground cover during early growth stages
Many companion crops are naturally winter-killed by frost, allowing the oilseed rape crop to continue growing without requiring additional management.
Why Are Companion Crops Used in Oilseed Rape?
The biggest driver behind companion cropping has been the challenge of establishing oilseed rape in areas affected by cabbage stem flea beetle (CSFB).
Young oilseed rape plants are particularly vulnerable to adult flea beetle grazing during establishment. Companion species can help reduce damage by masking the crop, creating physical cover and encouraging stronger early growth.
At the same time, some companion crops deliver additional benefits through nitrogen fixation, nutrient scavenging and improved soil health.
This combination of pest management and soil improvement has made companion cropping a key component of modern Integrated Pest Management (IPM).
How Do Companion Crops Help Reduce Flea Beetle Pressure?
While companion crops are not a guaranteed solution to flea beetle, they can contribute to a more resilient establishment strategy.
Several mechanisms are believed to help:
Crop Camouflage
Companion crops help break up the visual appearance of emerging oilseed rape plants, making it more difficult for flea beetles to locate host plants.
Protective Canopy
Fast-growing species such as buckwheat quickly create a canopy above emerging OSR plants, providing physical protection during early establishment.
Odour Disruption
Species such as fenugreek produce distinctive natural aromas which may help disrupt flea beetle host-finding behaviour.
Enhanced Crop Vigour
A rapidly established oilseed rape crop is often better able to tolerate pest pressure. Companion crops can improve growing conditions and help create stronger, more robust plants.
Best Companion Crops for Oilseed Rape
Buckwheat
Buckwheat is one of the most widely used companion crop species for oilseed rape.
Benefits include:
- Extremely rapid establishment
- Fast canopy development
- Excellent weed suppression
- Nutrient scavenging ability
- Frost sensitivity for easy winter kill
The dense canopy produced by buckwheat can help shield young oilseed rape plants during establishment.
The use of LIFAGO Buckwheat (Fagopyrum tataricum) versus conventional Buckwheat (Fagopyrum esculentum) is commonly used for OSR Companion Cropping due to the following benefits:
- More vigorous growth to provide a protective canopy of young cash crop plants
- Lower thousand grain weight than conventional buckwheat which provides higher plant population from the comparable sowing rate
- Smaller seeded and easier to drill with oilseed rape than conventional buckwheat
Berseem Clover
Berseem clover is valued for its ability to fix atmospheric nitrogen.
Key benefits include:
- Nitrogen fixation
- Fast establishment
- Strong early growth
- Soil health improvement
- Biodiversity benefits
Varieties such as TABOR Berseem Clover have become popular choices within oilseed rape companion crop mixtures.
The use of Single-Cut Berseem Clover, such as ‘TABOR’ versus Multi-Cut Berseem Clover is commonly used for OSR Companion Cropping due to the following benefits:
- Single-cut berseem clover variety that is killed by frost and does not regrow; whereas a multi-cut variety can re-grow in the Spring
- Grows vigorously as a nurse crop
- Deep taproots to condition the soil for healthy root development of cash crops
Fenugreek
Fenugreek has gained popularity because of its distinctive characteristics as an oilseed rape companion crop.
Benefits include:
- Rapid establishment
- Frost sensitivity
- Natural odour production
- Easy integration into companion crop mixes
Fenugreek is frequently combined with buckwheat and clover to create comprehensive companion crop systems.
Multi-Species Companion Crop Mixtures
Many growers now favour multi-species companion crop mixes rather than relying on a single species.
Combining different species allows growers to achieve multiple objectives from a single sowing.
Examples include:
Buckwheat and Fenugreek
A popular combination where:
- Buckwheat provides rapid canopy cover.
- Fenugreek offers additional crop masking and odour disruption.
Berseem Clover and Buckwheat
This mixture combines:
- Nitrogen fixation from berseem clover.
- Physical protection from buckwheat.
Buckwheat, Berseem Clover and Fenugreek
A three-species mixture delivers:
- Flea beetle protection
- Nitrogen fixation
- Biodiversity benefits
- Improved establishment
- Soil health improvements
For many growers, this provides the most complete companion crop solution.
Companion Crops and SFI CIPM3
Companion cropping is recognised within the Sustainable Farming Incentive through CIPM3 (Companion Cropping).
The aim of the action is to encourage integrated pest management approaches that support successful oilseed rape establishment while reducing reliance on conventional crop protection measures.
Companion crops used within CIPM3 can contribute towards:
- Integrated pest management objectives
- Biodiversity enhancement
- Sustainable crop establishment
- Resilient farming systems
This makes companion cropping both an agronomic and financial opportunity for many arable businesses.
When Should Companion Crops Be Sown?
Successful establishment is critical.
Many growers sow companion crops shortly before drilling oilseed rape, typically around:
- 5 to 10 days before OSR drilling
- At the same time as drilling
- Through a mixed seed approach where appropriate
The best timing often depends on field conditions, drilling method and the species selected.
Fast-growing species such as buckwheat and fenugreek are particularly effective when given a small establishment advantage before the oilseed rape emerges.
Are Companion Crops Suitable for Regenerative Agriculture?
Yes. Companion crops fit naturally within many regenerative farming systems because they promote:
- Increased plant diversity
- Living roots
- Improved soil biology
- Reduced reliance on inputs
- Greater resilience within crop rotations
They are increasingly viewed as an important tool for growers seeking to improve both soil health and crop performance.
The Future of Oilseed Rape Companion Cropping
As growers continue to look for practical solutions to cabbage stem flea beetle pressure and more sustainable establishment techniques, companion cropping is expected to remain a key part of successful oilseed rape production.
Whether the objective is improving establishment, supporting Integrated Pest Management, fixing nitrogen or meeting SFI CIPM3 requirements, companion crops can deliver multiple benefits from a single operation.
With proven species such as buckwheat, berseem clover and fenugreek, growers can build companion crop systems that support healthier oilseed rape crops, healthier soils and more resilient farming businesses.
