The weekly Pestwatch report indicates that egg-hatch for Wheat Bulb fly is still in its early stages in Cambridgeshire and Suffolk, but the big freeze of January 2010 is still causing some delay further North. With cold weather forecast for the second week of February, delayed and prolonged egg-hatch is likely to continue.
Starting in late January, results of the weekly soil sampling are issued by Dow AgroSciences and ADAS as Pestwatch reports. These reports reflect weekly data and provide advice on timely application of the soil insecticide Dursban WG. Weekly information can be accessed at www.dowagro.com/uk/cereal/pest/htm. Data published week-commencing the 8th February, egg-hatch was between 0% and up to 7.2% on organic soils in Cambridgeshire, which is a small progression since last week. Egg-hatch had yet to start in Yorkshire.
Sarah Hurry of Dow AgroSciences explains that the higher numbers of Wheat Bulb fly eggs detected in the autumn 2009 means that growers should remain vigilant and ready to treat vulnerable fields with Dursban WG (chlorpyrifos). "Dursban is an effective soil insecticide and should be applied at egg hatch at 1 kg/ha in 200-1000 litres of water. It has a long residual life in the soil of 6-8 weeks under normal conditions, meaning that most larvae will be controlled as they hatch over the longer period of time which is being predicted this year. Optimum conditions for activity occur when soil temperatures are above 5 °C. "
Dursban WG (75% w/w chlorpyrifos formulated as a Water Dispersible Granule) is recommended for the control of Wheat Bulb fly as well as Leatherjackets, Frit fly and Wheat Blossom Midge. For Wheat Bulb fly, two applications at dose rates of 1 kg/ha maybe applied up until flag leaf sheath extending (GS 39). It is packed in a 1 kg pack.
