With an early start to Wheat Bulb fly egg-hatch together with the one of the highest incidence of eggs being recorded in the autumn survey, vulnerable crops will need careful monitoring and decisive action may need to be taken to those crops at highest risk. This is the advice from the first of the weekly Pestwatch report issued in mid January which reports that egg-hatch for Wheat Bulb fly has already begun in Cambridgeshire, Suffolk, Hertfordshire and Lincolnshire.
Starting in mid 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 the timely application of the soil insecticide Dursban WG. Weekly information can be accessed at http://www.dowagro.com/uk/cereal/pest.htm. This week’s Pestwatch indicates that in week-commencing the 17th January 2011, Wheat Bulb fly egg-hatch in Suffolk was reported to be 9.1%, in Cambridgeshire/Hertfordshire on mineral soils was 15.1%, in Cambridgeshire on organic land was 4.8% and in Lincolnshire 8.5%.
"Wheat Bulb fly eggs are usually laid in Mid-July to August and hatch the following January or February. The exact conditions needed to initiate egg-hatch are not fully understood, but may be related to increasing diurnal differences in air and soil temperatures and accumulated day degrees. What ever the reason, Wheat Bulb fly egg-hatch is already well underway," says Sarah Hurry of Dow AgroSciences.
Sarah Hurry explains that results from the HGCA 2010 autumn survey of the incidence of Wheat Bulb fly eggs shows the numbers detected were the highest recorded since 2004 and the fourth highest since monitoring began in 1984. "This means that growers should remain vigilant. They should use the risk assessment charts to identify fields at risk and be ready to treat vulnerable fields with Dursban WG (chlorpyrifos). In any late drilled, struggling, backward or thin crops, it is worth considering an application of Dursban WG at the first available opportunity, as tiller survival will be very important in these crops."
"Dursban WG is an effective soil insecticide and should be applied at egg hatch at 1 kg/ha in 200-1000 litres of water. It will remain active in the soil for at least six weeks, which means that most larvae will be controlled as they hatch over a longer period of time."
"Dow AgroSciences in conjunction with ADAS will be monitoring egg-hatch and plant invasion on a weekly basis between now and mid-February. This will help farmers comply with the need to accurately access risk and so optimize timings and remains an important Stewardship responsibility," she says.
For further information, please contact Sarah Hurry, Dow AgroSciences on the Dow Technical Hotline on 0800 689 8899.
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.
