Pyrethroids offer scope for lower-cost fly control
Pyrethroids offer scope for lower-cost fly control
Carrot management came
under scrutiny at a recent
conference organised by the
Horticultural Development
Council. Edward Long reports
PYRETHROID insecticides which have replaced organo-phosphorous materials for carrot fly control can cut grower costs, provided their use is adjusted away from the traditional OP approach.
That is the finding of research at ADAS Arthur Rickwood and HRI Wellesbourne funded by HDC and the British Carrot Growers Association.
After MAFF imposed mandatory limits on the number of OP applications permitted in 1995, specific off-label approvals were granted for the pyrethroids Hallmark, Force ST and Decis on carrots.
"There has been a huge swing to them, with 98% of UK carrot crops now receiving no OP," says Jennie Blood Smyth of ADAS Arthur Rickwood.
But three years of research show pyrethroids must target the adult fly on the foliage rather than the larvae in the root as with OPs.
"If insecticide is to be sprayed on foliage only a third of the water volume is needed, and the best time to hit the fly is in the afternoon between 4-6pm when it comes in for tea," she says.
The first pyrethroid should go on a week ahead of the HDC/HRI forecast for 10% egg laying. With sprays aimed at leaves not roots there will be no chemical residue in the produce.
"Our work also shows there is no need to apply insecticides after the end of September, even if crops are not due to be harvested until the following May. With two fewer sprays costs will be cut," Dr Blood Smyth concludes.
New sprays, new advice – research shows the scope for fine-tuning pyrethroid sprays, says ADASs Jennie Blood Smythe.
Health protectors
Carrots could help protect consumers against a range of fatal cancers, says Tony Diplock, president of the International Antioxidant Centre at Guys Hospital, London. "If carotene is absorbed before it is converted it acts as an antioxidant, which is important for [limiting] cancer development. Carotene is not a magic bullet, but if our diet contains more it should dampen down the cancer risks later in life."
Carrot conference
The conference was organised by the British Carrot Growers Association, British Onion Producers Association, DMA Crop Consultants and David OConnor & Associates. It was sponsored by Elsoms Seeds.