Last Pestwatch report on Wheat Bulb fly this season

This week’s Dow AgroSciences Pestwatch report, which will be the final report for Wheat Bulb fly this year, shows that egg-hatch is now progressing rapidly at all sites. SAC have also confirmed egg-hatch at similar levels in Scotland to those in Yorkshire. There is plant invasion of Wheat Bulb fly in East Anglia and Lincolnshire.

Week-ending the 2nd March 2012, Wheat Bulb fly egg-hatch in Suffolk on mineral soils was reported to be 68.8%, in Cambridgeshire/Hertfordshire on mineral soils it had increased to 58.6%, North Lincolnshire (a new site for 2012) on mineral soils it had also increased to 70.1%, Yorkshire on mineral soils it was at 14.8% and in Cambridgeshire on organic land 46.3%. All sites have seen a significant increase in egg-hatch in the last week.

Sarah Hurry of Dow AgroSciences says that it is now too late for an egg-hatch spray in East Anglia and Lincolnshire. “In the North and in Scotland fields at risk need Dursban WG (chlorpyrifos) at the first opportunity as tiller survival remains important. Dursban WG can be applied to frosty ground, but should not be tank-mixed. It should not be applied to frozen soil where rain could result in run-off to water courses.”

There is an interval of 14 days between applications of Dursban WG and GF-2070 or Broadway Star, regardless of weather conditions, and a longer 4 week interval between Dursban WG applications and approved formulations of iodosulfuron-methyl-sodium and mesosulfuron-methyl, for crop safety reasons.

When applying Dursban WG for Wheat Bulb fly, growers should use LERAP rated 3 star nozzles and adopt a 20 metre no-spray buffer zone near to watercourses or a 1 metre near to dry ditches. This advice is part of a new Stewardship ‘Say NO to drift’ initiative which aims to support the future availability and use of insecticides containing chlorpyrifos.

Dow AgroSciences will be issuing Pestwatch reports for other insect pests including leatherjackets and Wheat Blossom midge later on in the year.

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.