PROTECTING WATER quality by preventing pesticides reaching water is the primary aim of the Voluntary Initiative’s autumn message, ‘Burst one bubble and we’re all in trouble.’

In addition to the campaign, FWi will be providing readers with regularly updated information to prevent pesticides finding their way into watercourses.

Latest report from VI manager, Patrick Goldsworthy

22 November 2005

After the first week of widespread late-autumn frosts growers should check soil conditions before spraying. Water and soil field run-off can be influenced by temperature, even with short-term soil freezing.

Beware of applying herbicides in a mild spell after a frost, as soil beneath the top few centimetres could still be frozen. The risk of surface run-off is even higher if rain is forecast.

A long period of low temperatures on wet soil can cause soils to be deeply frozen, with a high risk of surface run-off even when the soil surface has thawed.

The warning applies to the sprayer filling and cleaning area as well, especially if this is on grass or in the field. Drops of concentrated and dilute spray can also run off the frozen farm tracks.

Finally, remember to store sprayers undercover to avoid damage to pipework and nozzles from frozen water.

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Previous reports

21 October 2005

Crops are very forward after the past month’s exceptionally high soil and air temperatures. As a result herbicide application is likely to begin some two weeks earlier than usual.

Despite recent heavy downpours, soil moisture deficits are still unusually high (90-132 mm) for the time of year in central and southern Britain.

With good soil management programmes in place, run-off of autumn applied residual herbicides is unlikely at the moment. But, underdrained soils still present a higher risk.

When field drains begin to run they could contain unacceptably high herbicide levels, depending on soil cultivation depth and soil texture.

Growers in areas of high Soil Moisture Deficit (SMD) on medium to light soils with under-drainage should delay herbicide application until the top 8cm of soil are well wetted.

If crops are too forward, then consider delaying weed control until the spring.

14 October 2005

Recent heavy rain in the north and west of the country could mean run-off on sloping fields of soil and water, carrying pesticides into watercourses, the Voluntary Initiative has warned.

With autumn drilling almost complete, and many farmers getting on with post-emergent herbicide applications, the VI is urging growers to be prepared to wait until conditions improve.

“Avoid spraying if drains are flowing, soil moisture capacity is high and more rain is forecast,” said the VI’s Patrick Goldsworthy. “And remember compacted tramlines can act as channels moving pesticides and soil particles straight into watercourses.”

Protecting water quality by preventing pesticides reaching water is the primary aim of the Voluntary Initiative’s autumn message, ‘Burst one bubble and we’re all in trouble.’

The ‘bubble’ message is set out in a cartoon postcard for farmers, sprayer operators and advisers, as part of the VI’s autumn H2OK? – Keep it Clean campaign (see Crops magazine, 15 October 2005).

“The issues can be complex,” added Mr Goldsworthy. “Weather, soil management, sprayer setting, farmyard and field practice, and pesticide choice could all impact on the risk of pesticides entering water.”

Click here for the isoproturon and chlortoluron application decision tree or for further information, advice and links to other best practice websites visit www.voluntaryinitiative.org.uk