Field results have suggested that cabbage stem flea beetle attacks in oilseed rape crops could be mitigated with silicon.
Plants use silicon to create a physical barrier to attacks, producing a hard layer of opals within the leaf cuticle.
“Two to three applications of silicon have been sufficient to reduce the feeding damage appreciably,” says Sustainable Ag Solutions’ Chris Coates.
The Yorkshire-based independent agronomist has recommended silicon in place of insecticides for the last three years. Initially, he used Zeme (potassium silicate) in a tank mix with insecticides, before moving to silicon alone. He reports no change in the results.
“Applications must be made early but should be balanced against the plant presenting a big enough target. Standard cotyledon stage is ideal,” Chris suggests.
He adds that any application should be made prophylactically, as silicon is not a control for flea beetle.
“There’s been very little flea beetle damage so far this year, which I suspect is down to the wet weather having disrupted insects’ lifecycles. Now we’re monitoring flea beetle levels and will be primed to make applications if numbers rise.
“If numbers don’t rise enough to merit a separate application, then we’ll wait to tank-mix Zeme with the first herbicide application.
“At £7/ha, it’s a very affordable, very effective option for controlling this pest without recourse to insecticides.”
Dan Lievesely, an independent agronomist with DJL Agriculture, has also been experimenting with silicon applications.
“I’ve always believed that disease and pest pressures come easily to weak crops,” he says. “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.”
Having used various forms of potassium silicate over the last five years, he has noted that it not only holds off flea beetle, but also helps with lodging and nutrient management.
“My recommendation centres on three applications of Zeme before Christmas,” he explains. “The first at cotyledon stage, the second at 1-2 true leaves, and the third as the last application once you’ve applied Kerb (propyzamide).
“We’ve avoided insecticides completely since starting to use silicon.”
Dr David Marks, co-founder of Levity Crop Science, adds that silicon can bring considerable benefits 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.”