Wheat Bulb Fly

Wheat Bulb Fly

Report 4 - 8th February 2013

In support of product stewardship of Dursban^® WG, Dow AgroSciences in conjunction with ADAS, will be monitoring Wheat Bulb fly egg-hatch and subsequent plant invasion. This helps farmers comply with needs to accurately assess risk and thus optimize product usage.

The latest HGCA Wheat Bulb fly survey indicated that only 3% of sites sampled in England were above the threshold of 250 eggs/m².  This was the equal lowest recorded since 1984. The full survey results are available on the HGCA website www.hgca.com.  A similar low risk was indicated by surveys in Scotland by SAC Consulting/SURC.

In view of these low counts it was predicted that Wheat Bulb fly would pose a limited threat to crops sown before November and many crops did not receive any Wheat bulb fly seed treatment. However the wet autumn delayed drilling and plant development.  Therefore many crops were sown late and for these a lower threshold of 100 eggs/m² will apply.  In the east of England 47% of monitored sites were above this level and in the north of England 27% of sites were above this level.  In Scotland 30% of fields sampled have egg counts exceeding 100 eggs/m².  As a result later sown crops will still potentially be at risk if they have only one or two tillers at the time of Wheat Bulb fly egg-hatch. In this instance an egg-hatch spray may be worthwhile even if egg numbers are only in the moderate infestation category (100-250 eggs/m²).

Slow developing early drilled crops will also need to be monitored and may benefit from an egg-hatch spray if they have low numbers of tillers and egg numbers are in the moderate infestation category.

Progression of egg-hatch will be monitored into February.

Results

Egg-hatch is underway in East Anglia, North Lincolnshire and now in Yorkshire.  Although the low egg numbers this year give error, overall, egg-hatch has progressed this week.  There is also some plant invasion in the south although all the larvae are sitll only first instar.

* CAUTION.  The low egg counts this year means we are recovering fewer eggs which gives data error on precentage egg-hatch.

What does this mean for you?

In the absence of egg counts for specific fields, risk assessments for treatment must be made on the basis of locality, previous cropping, drilling date, plant population, tillering and soil type. Use Risk Assessment Charts to identify fields at risk. Once conditions allow apply Dursban WG at 1.0 kg/ha in 200 to 1000 litres per hectare of water. In late drilled, struggling, backward or thin crops an application of Dursban WG should be considered at the first available opportunity to promote tiller survival. In the event of a prolonged egg-hatch a repeat application of Dursban WG may be required, particularly on organic soils.

If necessary, Dursban WG can be applied to frosty ground but should NOT be tank mixed.

An interval of 14 days must be observed between applications of Dursban WG and UNITE^® or Broadway^® Star, regardless of weather conditions. For approved formulations of iodosulfuron-methyl-sodium and mesosulfuron-methyl leave a longer interval of 4 weeks for crop safety.

Equity^® also has recommendations for Wheat Bulb fly.

Use low drift nozzles and extend buffer zones to preserve Dursban WG use!

Protecting the crop protection products we have available today is more important than ever.  A new ‘risk assessment’ for chlorpyrifos, under its routine EU/UK review, means that the existing label no-spray buffer zones adjacent to watercourses are no longer considered sufficient protection for aquatic organisms by the Chemicals Regulations Directorate (CRD). An industry stewardship initiative – ‘Say NO to Drift’ is in place.   The aim of this campaign is to protect the future availability and use of chlorpyrifos. 

When spraying Dursban WG or Equity for Wheat Bulb fly:

• Use LERAP - low drift - 3 star rated nozzles
• Adopt a 20 metre buffer zone (1 metre dry ditch)
  

Trials conducted by Dow AgroSciences has shown that control of Wheat Bulb fly is not affected when Dursban WG is applied using a LERAP - low drift - 3 star rated nozzle (compared to a Flat-fan nozzle).

Use plant protection products safely. Always read the label and product information before use. For further information including warning phrases and symbols refer to label.

® Trademarks of Dow Chemical Company ("Dow") or an affiliated company of Dow.  All other brand names are trademarks of other manufacturers for which proprietary rights may exist.

Broadway Star contains pyroxsulam and florasulam. 
Dursban WG contains chlorpyrifos.
Equity contains chlorpyrifos.
UNITE contains pyroxsulam and flupyrsulfuron-methyl-sodkum