Five key insights for getting the most out of your oilseed rape this year

With confidence returning to oilseed rape and areas recovering in some regions, our trials are highlighting five practical priorities for improving resilience and reducing the impact of cabbage stem flea beetle (CSFB) in both autumn and spring.

Oilseed rape remains a crop where small decisions early in the season can set the outcome months later. CSFB is still part of the picture, even where pressure feels lower than it did a few years ago. Your best chance of success comes from stacking sensible choices across variety, drilling timing, establishment and spring recovery.

These insights are drawn from Agrii’s regional trials and monitoring work and are intended to support practical decisions on farm.

1) Do not focus on autumn vigour alone

Establishment and avoiding adult CSFB damage in the autumn has been a major priority in recent years. However, drilling very early can carry costs later in the season.

As Agrii’s David Leaper explains, early drilling reduces your ability to interrupt the CSFB cycle and can increase the risk of larval damage the following spring. It can also raise disease exposure, including light leaf spot, clubroot and Verticillium.

Our trials have looked at vigour as a two-stage process, with measurements taken in mid to late December and again in late February. Results show a strong correlation between spring vigour and the physical damage caused by larvae.

Historically, autumn vigour has dominated variety choices, supporting the rise of varieties such as Extrovert, Expower and Campus. The learning now is that spring vigour matters at least as much, and often more, for the outcome of the crop.

Our conclusions are that there is little to separate varieties for adult CSFB attack in the autumn. Susceptibility is broadly similar. Differences become far more visible in spring regrowth, and this is where variety choice has a stronger influence on resilience.

There are ways to reduce adult damage risk in the autumn. Larval impact in spring is harder to influence once the crop is established. This is why drilling date and spring vigour should sit at the centre of planning.

2) Be realistic about CSFB numbers

Lowering the frequency of oilseed rape in rotations has helped reduce CSFB pressure in many areas. That said, it is still too early to relax.

In a CSFB survey carried out in February, Agrii was involved in sampling 177 crops. While overall pressure is lower than in some previous seasons, the pest remains widespread.

Of 50 crops assessed in detail, only three had no larvae present. The average was three larvae per plant. That is still enough to affect crop performance, particularly where spring recovery is slow.

This is why our trials continue to focus on crop tolerance and recovery, as well as reducing pressure where practical.

3) Prioritise spring biomass

Across our trials, varieties that build biomass quickly in spring tend to be the highest yielders. There is a clear relationship between spring biomass and final gross margin.

In Spring 2025 trials with around 30 varieties, Maverick, Kanzzas and Vegas built biomass most quickly. Over five years of trials, we have also seen a strong correlation between spring biomass production and reduced larval damage.

Harvest results from 2024 and 2025 support the same trend. Maverick is currently at 110% of controls and Vegas at 107% of controls in Agrii trials.

These are the same varieties that previous work identified as quick spring biomass builders with lower larval damage.

4) Use companion crops to support resilience, but keep expectations realistic

We have trialled a range of companion crops with oilseed rape to assess how they influence CSFB pressure and crop performance. Some options are showing consistent value.

Buckwheat, when established well, reduced adult CSFB damage during establishment and continued to do so through the autumn until the first cold nights when it died back. This extended period of protection reduced egg laying and resulted in lower larvae numbers per plant in spring.

Plots with a buckwheat companion also appeared more vigorous and more even in spring, likely due to reduced larval damage.

Which buckwheat?

In our work, Fagopyrum tataricum (Lifago) was more effective than common buckwheat (F. esculentum), although both types performed well.

Other companion options

In lower CSFB pressure situations, where soil structure and nutrient building are a priority, options such as Tabor berseem clover and Bingo purple vetch can support establishment and early growth.

Companion crops can support the establishment strategy. They should not be treated as a single solution to CSFB. They work best as part of an integrated approach alongside drilling timing, variety choice and sound agronomy.

5) Do not put yield above everything else

Variety decisions are increasingly based on more than a headline yield figure. Many growers are prioritising traits that protect performance in their region and reduce risk in challenging seasons.

Breeders have made major progress in stacking traits, strengthening disease resistance and improving standing ability. Our trial work continues to show the value of those traits when conditions tighten.

In 2025, light leaf spot levels have been unusually high in the west of the country. Where varieties lacked resistance, performance suffered.

This is exactly why Agrii runs regional variety trials. National figures matter, but they do not always reflect the pressure you see locally.

Last year Maverick, Vegas and Adapt were at the top of our trials. Kanzass also performed strongly. Although it did not make the final Recommended List cut, it carries an 8 for light leaf spot resistance, which has been valuable for growers in certain regions this season.

Yield remains important. However, if other limiting factors in your area are ignored, a small yield advantage on paper can disappear quickly in the field.

Practical takeaways for this season

• Plan drilling date around CSFB cycle disruption as well as establishment.
• Choose varieties with strong spring vigour and rapid spring biomass development.
• Assume CSFB remains present and plan accordingly, even if adult pressure looks lower.
• Use companion crops where they fit, with realistic expectations and good establishment.
• Balance yield with disease resistance and local risk factors, particularly light leaf spot.

If you want to review variety options, drilling timing or companion crop choices for your area, speak to your Agrii agronomist. We can also share the regional trial detail that sits behind these findings.