Yield losses from cabbage stem flea beetle (CSFB) are estimated to cost growers about £70 million a year in lost output, roughly equivalent to 5 -15% of total crop value, but with no easy means of control, what options are there to safeguard the future of Britain’s most popular, and for many, most profitable, break crop?
After the loss of neonicotinoid seed treatments most growers resorted to foliar insecticides to protect crops, but with resistance to pyrethroid insecticides already present among CSFB populations, its increased use served only to hasten the spread of resistance. A problem that began in East Anglia is now a concern across Great Britain.
The impact of this problem extends beyond growers; breeders need a solution too. KWS has variety development trials across Great Britain, but three trials at two locations – Old Weston, north-west of Huntingdon, and Worlingworth, east of Stowmarket in Suffolk – have been heavily affected.
These trials form an important part of our variety development programme, so when 782 plots, equivalent to about 50% of the plots in these trials, demonstrate some level of CSFB larvae damage, it raises concerns. It also leads to questions, first among them is: why roughly 50% and not 80% or more?
The level of detectable damage varied between the sites, but perhaps more significant is that some varieties showed more damage than others. The ability of CSFB to seek out certain varieties within a randomised trial is a significant observation and one that warrants further investigation.
As can be seen from the photos below Flamingo (in the plot pictured on the right) is a variety that exhibits low level damage from CSFB larvae. This observation was mirrored in the AICC Southern strip trials, where Flamingo looked better in the plots and at harvest produced the second highest yield in trial of 4.75t/ha.