A UK trial undertaken by ProCam and biostimulant specialist Orion Future Technologies has established that strengthening oilseed rape (OSR) crops can help reduce indicators of cabbage stem flea beetle (CSFB) and improve yield potential.

CSFB remains a key concern for OSR establishment in the UK. A 2025 trial using Deneb, a biostimulant with 4% silicon (SiO₂), and natural plant extracts which exhibit a strong scent profile, has demonstrated to reduce interest in CSFB feeding, resulting in a lower larval count and infestation score. The trial also showed yield increases and an improvement of stem width by using two applications of Deneb at a rate of 0.5 L/ha and 0.25 L/ha.

"The infestation score fell from 4.5 in the untreated crop to 3.3 with two applications of Deneb at 0.5 L/ha — a reduction of approximately 27%. At 0.25 L/ha the score was 3.8, representing a reduction of approximately 16% against the untreated," says Orion FT agronomist Mike Stoker.

He suggests that similar reductions were seen in larval counts which reduced from 6 in an untreated crop to 5 with the 0.5 L/ha application.

"Silicon helps to improve plant's natural defences and one of the main takeaways from this trial was stem width which saw up to a 0.3mm increase compared to the control. While this seems like a very small gain, it is an important reference point for the overall development and establishment of the plant," says Mr Stoker.

He points to other benefits that silicon biostimulants provide, including helping plants to develop deeper seeking, stronger root structures that help build resilience during and after establishment.

"Gains made during establishment ultimately help to improve yield and, in this trial, the 0.5 L/ha application crop showed a 7.1% increase in yield compared to the untreated crop. This produced 4.9 t/ha which represented an increase of 0.3 t/ha — an increase of 0.4 t/ha, equivalent to approximately 7.8% over the untreated crop," he says.

"However. Although the trials data evidenced a marginal yield response, agronomically we recommend achieving a target dose of 0.5 L/ha, either as a single application or split into two applications of 0.25 L/ha," he adds. 

Mr Stoker points out that the greater increase in yield achieved by applying a smaller dose of Deneb is indicative of how specific biostimulants work and that growers should not always be tempted to use more to get better results.

"Biostimulants have the capacity to improve the natural defences of a plant by accelerating its natural responses. Potentially overloading this by applying more than is needed is unlikely to see any significant gains and, in the case of this trial, the balance was reached by applying two smaller doses," he adds.

He concedes that, while the results are encouraging, Deneb and other biostimulants should not be viewed as a solution for insecticidal control. Instead, he sees the benefits of applying such products as an enhancement of any chosen integrated pest management (IPM) strategy.

"Deneb should be considered in the context of an integrated OSR establishment strategy rather than as a replacement for CSFB control. However, this trial has shown that helping to build plant resilience during establishment by using biostimulants could be a valuable option for agronomists looking to help growers increase OSR yield," he concludes.