OSR CSFB establishment tip: Variety vigour and seed quality

Cabbage stem flea beetle (CSFB) management in oilseed rape (OSR) requires a combination of approaches. Using quality seed and a vigorous variety can help keep the crop ahead of pest damage.

Using good quality seed will help establish robust crops that can better withstand attack from CSFB.

Poor quality seed can:

• Fail to germinate, which leads to patchy establishment
• Reduce germination rate, which causes variable and slower growth
• Increase pest pressure on plants that establish

Large seeds are often associated with better germination and provide a stronger start for seedlings.

However, oversized seed can be a disadvantage, particularly where moisture is sub-optimal.

Therefore, aim to screen any farm-saved sources for seed between 1.8 mm to 2.2 mm.

You can use thousand seed weight (TSW) as a proxy measure.

In addition to seed size, test farm-saved seed for germination to identify viable and good quality seed lots.

Note: Priming seed before sowing starts germination earlier.

There are very few seed treatments approved for UK OSR.

Some products are approved for application to OSR seed in the EU, which can be imported and sown in the UK.

UK field trials, such as those run by NIAB, showed positive effects associated with seed treatment products.

Products tested included Lumiposa, which has the active ingredient cyantraniliprole.

Although seed treatments may become part of the solution, the impact of such approaches is not clear.

Novel treatments, including Lumiposa, are currently being assessed in our CSFB Research+ project.

Note: Always check when treated seed needs to be sown by.

Plants with good establishment and autumn vigour can grow away from pest damage.

The key is to get crops to growth stage 14 as quickly as possible, which is when the fourth leaf unfolds.

Crops become relatively tolerant to leaf loss at subsequent growth stages.

As vigorous crops have greater leaf material, more can be ‘sacrificed’ to the pest before it impacts productivity.

Variety traits that may reduce the impact of CSFB feeding damage, including vigour, were assessed in trials conducted during 2017, 2018 and 2019.

The influence of vigour was clearly seen at two trial sites in the 2018/19 growing season, which included vigour and damage assessments around GS14.

At these trial sites, some varieties were more vigorous than others and were generally associated with lower percentage leaf area losses.

Variety trials at several sites during 2021, 2022 and 2023 also found a significant association between weaker autumn vigour and higher percentage leaf area losses.

Once again, these trials detected significant differences between varieties.

They also showed that lower plant populations were significantly associated with a higher leaf-area loss.

The research also suggested that varieties with good spring vigour may be better able to tolerate feeding damage from CSFB larvae. 

If sowing after mid-August, consider a vigorous variety that provides rapid early growth that can withstand attack from adult CSFB.

If sowing before mid-August, consider a variety with slower autumn vigour and good early spring growth and biomass to limit larval damage.

In this situation, the crop should emerge and develop sufficient leaf material before peak CSFB migration.

Importantly, it will reduce the risk of such varieties reaching stem extension too early.

Due to the complex nature of CSFB, never rely on a single strategy.

Use integrated pest management (IPM) to layer as many techniques as possible to minimise the risks.

This page covers one component of the ‘chase perfection at establishment’ strategy.

The home page also includes information on CSFB Research+, which is generating evidence to further improve strategies.

To view all our CSFB research projects, search ‘CSFB’ on our research page.