A spell of hot weather has led to a rise in cabbage stem flea beetle (CSFB) activity, leaving newly emerging crops vulnerable to attack.
Increased flea beetle activity has been reported up and down eastern regions of the UK, from East Anglia up to the Scottish Borders and so growers are advised to monitor newly emerging oilseed rape (OSR) crops closely for signs of damage.
The activity of the pest seems to be increasing along with temperatures and as drilling continues into drying soils, OSR sown in the next few days could be at risk of damaging attacks, according to Frontier crop production specialist, Paul Cartwright.
He says: “Although early drilled crops have grown readily in moist seedbeds and little or no damage has been reported, there are signs that seed being drilled now into drier seedbeds may face a more challenging time.
“There is clear evidence of growing flea beetle activity this week and that means that crops sown in the main drilling window (mid–late August onwards) are likely to encounter higher grazing pressure as they emerge.”
Out on farm, many growers are reporting flea beetle damage...
Growers that are yet to drill their OSR, are advised to promote early crop growth using nutrition, good seedbed preparation, adequate consolidation and biostimulant applications where possible.
Mr Cartwright says: “The first few weeks of establishment are an anxious but important time for all of us involved in OSR management but prevention – in the form of good establishment - is always better than cure in the fight against the flea beetle.”
An AHDB funded project has recently found the pyrethroid resistance in CSFB is widespread in the East, with further resistant populations detected in Yorkshire and the South. It is therefore vital that pyrethroids are used at full rates and only when thresholds are exceeded to minimise the development of further resistance, according to ADAS.
Treatment thresholds currently advise that is a spray is only necessary if: