The withdrawal of neonicotinoid seed treatments will leave young oilseed rape plants unprotected from these voracious pests according to BASF’s Clare Tucker. Ms Tucker explains: “The yellow water traps are really simple to use and they are a quick way to assess whether a pyrethroid needs to be applied.”
The company is only advising growers to spray if crop damage thresholds have been reached, because of the threat of pyrethroid resistance.
“Cabbage stem flea beetles resistant to pyrethroids have been detected in Germany and there is a concern that this might spread to the UK,” she says.
The adult cabbage stem flea beetle is about 3-4mm long, blue-black or light brown in colour. The adults chew ragged holes in the cotyledons and first true leaves of the young crop.
“The level of damage from this pest is variable,” she adds. “Adult feeding can range from a few shot holes requiring no treatment to, occasionally, total crop loss.”
“It is also important to concentrate on the early agronomy of the crop – well-established plants can grow away from adult feeding and strong plants will tolerate a higher level of larval damage without any yield penalty.”