Cabbage stem flea beetle: Breakthrough in bid to stop beetle attacks which have devastated Yorkshire crops

“Two to three applications of silicon have been sufficient to reduce the feeding damage appreciably,” says Sustainable Ag Solutions’ Chris Coates.

Based in Yorkshire, the independent agronomist has been recommending silicon in place of insecticides for the last three years, after attennding a farmer meeting where the idea was first floated.

Mr Coates’ finding follows the total area of oilseed rape in Yorkshire decreasing from 57,927 hectares in 2023 to 39,322 this year.

Since the ban on the use of neonicotinoid seed dressings to control insect pests, the cabbage stem flea beetle has caused a decline in oilseed rape yield.

Recent yields have been the lowest recorded in decades, due to the reduced ability to control pests combined with unfavourable growing conditions.

In early usage, Mr Coates applied potassium silicate in tank-mix with an insecticide, before stripping applications back to silicon alone with no appreciable change in results.

“Applications must be made early but should be balanced against the plant presenting a big enough target. Standard cotyledon stage is ideal,” Mr Coates said.

As the silicon is not a control for flea beetle, Mr Coates says applications should be made prophylactically.

“At £7/ha, it’s a very affordable, very effective option for controlling this pest without recourse to insecticides.”

A similar sentiment – transitioning farmers away from harsher inputs – lay behind Dan Lievesely’s exploration of silicon.

“I’ve always believed that disease and pest pressures come easily to weak crops,” explains the independent agronomist, from DJL Agriculture. “Besides its physical properties, silicon has a role in several plant metabolic functions. Boosting the crop’s inbuilt resilience to attack, be it from pests or pathogens, and reducing abiotic and

biotic stress, has to be a more sustainable option.”

Mr Lievesely has used various forms of potassium silicate over the last five years, finding it a good tool to manage not just flea beetle attack but also lodging and nutrient management.

Dr David Marks, co-founder of Levity Crop Science, says silicon, while rarely used as a crop input, brings considerable benefit to crop health. “Not only is it implicated in production of anti-stress hormones and antioxidants, silicon’s also vital for phosphate redistribution and trace element transport.

“It also improves crops’ nitrogen recovery abilities, especially during dry spells when soil nitrogen availability can be very low.”

Dr Marks added: “Standard foliar silicon always has some effect, but because the plant quickly locks it away into opals – a one-way process – it becomes unavailable

to the plant again.