BCPC seeks justification of interim aquatic buffer zones

Chemicals Regulation Directorate (CRD) has introduced its new interim assessments of aquatic buffer zones, and the first new registrations under this system are appearing. Dimethachlor requires a 10 metres buffer zone; diflufenican requires 12 metres. If the method of assessment used by CRD was applied to chlorpyrifos, a 75 metres buffer zone would be required! (though 20m is the maximum).These buffer zones apply to all watercourses, big or small (though only when there is water in the watercourse – and any wider than 5m cannot be reduced.

"These are worryingly large increases in width,” says Dr Colin Ruscoe, Chairman, BCPC.” "The reduction of available productive land that will result from these zones is in direct opposition to the drive for sustainable intensification. Every hectare of crop not grown in the UK, with its highly productive agriculture, requires even more hectares of crop to be grown elsewhere in the world. The move will also be counterproductive because farmers will avoid using products requiring wide buffer zones altogether, resulting in greater reliance on fewer products/modes of action – so risking faster development of pesticide resistance. This will increase the problems of the reducing number of products that will be available due to new EU regulations.”
 
Are present practices and products really threatening water quality and ecosystems? The basic drift model used to develop the long-standing LERAPs scheme was based on a narrow boom-width sprayer, travelling slowly. Drift from wider boom sprayers travelling at 12-14 kph, using standard hydraulic pressure nozzles, can be significantly higher.

However, it does not appear that the new, wider zones are driven by problems in practice. Indeed point source and run-off can be far greater threats to water sources than spray drift. Only 1% of water bodies monitored by the Environment Agency failed their Environmental Quality Standards for pesticides in 2010 – with no evidence that these were due to spray drift.
 
Furthermore, these water bodies were lakes and rivers - not farm ditches, many of which are not sustained aquatic ecosystems. The French authorities require buffer zones just for larger on-farm streams and water bodies that may have sustained aquatic ecosystems.
 
Drift-reduction adjuvants are not the answer – they are product-specific and may reduce the drift of one product while increasing it for another. The LERAPs scheme – which BCPC helped draw up – allowed reduction in buffer zone width, by use of lower doses and/or reduced drift spraying techniques. This resulted in the use of lower drift air-induction nozzles for most spray operations – and new engineering solutions can reduce drift even further. The agricultural equipment industry has made huge strides in producing nozzles and sprayers that can greatly reduce the risk of spray drift. This is not recognised at all by inflexible buffer zones – providing no incentive for users to adopt drift reducing equipment and techniques.
 
There are further options. Drift studies are carried out with short vegetation downwind and taller vegetation in the buffer will trap a significant amount of drift – such vegetation, correctly managed – could also greatly enhance biodiversity.
 
"These interim buffer zone measures can and should be superseded by measures based on relevant science, to include mitigating factors, from which CRD can develop simple solutions which meet the requirements of both food production and conservation,” concludes Dr Ruscoe.