Northern crops face increased threat from orange wheat blossom midge

UK - May 31, 2007

Wheat growers in North East England need to be on the look out for yield-robbing infestations of orange wheat blossom midge as weather patterns change, according to a leading agronomist. 

“We are finding that orange blossom midge is becoming an increasing problem in the North East,” warns Jim Calvert senior agronomist with BCS Agriculture. “It’s a pest Yorkshire and Teesside growers are not so familiar with, so we are checking their high risk fields and putting out traps to make sure we spot them early.  The way crops are growing, it’s quite likely that midge hatch could coincide with ear emergence.” 

Dr Toby Bruce, a leading researcher at Rothamsted, suspects climate change may have played a role in this move north and the increasing frequency of attacks.  

“In past years, it was unusual for soils to be warm enough for adults to emerge at ear emergence,” says Dr Bruce. “Recent mild winters and warm summers make it more likely that midge hatch will coincide with ear emergence in some parts of the UK in most years.” 

Loss of natural predators and the inadvertent use of highly susceptible varieties may also contribute to the problem.  

“The use of broad spectrum insecticides will have affected natural predators and parasitoids, while sowing highly susceptible varieties such as ‘Option’ and ‘Tanker’ will also have contributed to increased midge populations,” warns Dr Bruce. 

“When wheat orange blossom midge reaches the infestation thresholds that justify treatment, growers should apply Dursban WG at 0.6kg/ha in 200L/ha of water,” recommends Dow AgroSciences Regional Business Manager, Chris Pye.  “Timing is critical so don’t delay treatment to coincide with fungicide applications if there is any risk of missing the best application time for Dursban. We also recommend leaving a 12m buffer around the field zone margin to allow natural predators to re-colonise the field rapidly.”  

“While other products are available for use this year, only Dursban WG will control larvae before they enter the floret as well as adult midges,” adds Mr Pye.