Wheat Bulb fly sampling begins in earnest

UK - January 25, 2010



Improved weather conditions have allowed Wheat Bulb fly sampling to begin in earnest and it looks as if the cold conditions have slowed down egg development and delayed egg-hatch, according to Dr. Steve Ellis of ADAS.

Dr Ellis explains that soil samples are taken during the autumn from sites considered to be at risk, to establish the number of Wheat Bulb fly eggs present.  "Results from the HGCA's autumn 2009 survey of the incidence of Wheat Bulb fly eggs shows the numbers detected to be higher than in recent years. So we need to be vigilant and be ready to treat vulnerable fields."

He goes onto explain that weekly soil sampling is then carried out in fields with high or very high egg numbers present during January, February and March in order to monitor egg-hatch and then plant invasion.  "With the improving weather conditions, soil sampling began in earnest last week and it appears that, although egg-hatch started in Cambridgeshire, the "Big Freeze" of January 2010 has caused some delays further North. The cold conditions has delayed egg hatch."

Starting this week, 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

Sarah Hurry of Dow AgroSciences explains that Wheat Bulb fly eggs are usually laid in mid-July to August, before hatching the following January or February.  "The exact conditions needed to initiate egg-hatch are not fully understood. However it is related to increasing diurnal differences in air and soil temperatures and accumulated day degrees."

"In most years hatching does not start until at least mid-January. Last year hatching was delayed until the end of January in England and early-February in Scotland. With the recent exceptionally cold weather it is unlikely to start any earlier this year."

Growers should be preparing to apply Dursban WG to vulnerable crops.  "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 which means that most larvae will be controlled as they hatch over a longer period of time."

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.