Vigilance needed despite lower wheat bulb fly risk

UK - January 21, 2008

Although the risk of wheat bulb fly damage is lower this year than in recent years, growers must remain vigilant warns Dow AgroSciences. 

“HGCA’s wheat bulb fly monitoring predicts the risk of attack this year to be lower than for the last few years,” explains David Roberts, Dow AgroSciences technical specialist. “Of the 35 fields sampled, 9 have egg counts above the 250 eggs/m² threshold. Therefore, the risk is below the long term average.” 

To help growers choose the right time for application, the Dow AgroSciences Pestwatch service, in conjunction with ADAS, is monitoring egg hatch at five high-risk sites in Cambridgeshire and East Yorkshire. Sampling has already begun. The latest egg hatch results show that only 5.5% of eggs have hatched. If treatment is needed, growers should delay until around 15% of eggs have hatched. Updates of egg hatch and plant invasion will be published each week on http://www.dowagro.com/uk/cereal/pest.htm.  Egg hatch will carry on as long as weather conditions remain mild,” warns David Roberts. “And even though predicted risks are lower this year, growers should still carry out a Risk Assessment, available from the Dow AgroSciences website, and check late drilled or backward crops, especially those sown after sugar beet, as they can be susceptible where egg populations are as low as 100/m².

Where infestations of wheat bulb fly threaten yields, Dursban WG (chlorpyrifos) should be applied at 1.0 kg/ha.