Pesticides - Best Practice Guides

During Spraying

Avoiding Drift - A Practical Guide


Introduction

Spray drift can lead to a number of problems when using pesticides. It not only leads to poor control due to underdosing, but can pollute water, damage sensitive crops and the environment. Pesticide legislation requires that all spray is confined to the land, crop, structure or material that is treated. Follow the advice below and minimise the risk of spray drift, thus protecting your own and neighbours crop, the public and the environment.

Before spraying

  • Listen to the local weather forecast and adjust work accordingly. Do not spray if wind speed and direction would cause drift onto sensitive areas.
  • Ideal spraying conditions are a Force 2 light breeze (3.2-6.5 km/h) blowing away from sensitive areas. This would be a breeze strong enough to be felt on the face and to rustle leaves (see table below).
  • Check each product label for spray quality recommendations and adjust your applicator and work programme accordingly. Where practical choose a coarser quality sprays as they reduce the probability of drift.
  • Check and follow statutory product label advice on no-spray zones.
  • Consider leaving a 2 m unsprayed strip close to the field margin or sensitive areas (such as watercourses, ponds, gardens and wildlife conservation areas).
  • Ensure that the sprayer is properly maintained and calibrated for the job in hand.
  • In the field, check the wind speed and direction and, if necessary, amend your plans.
  • Consult the BCPC Hand-operated Sprayers Handbook, Boom Sprayers Handbook or Fruit Sprayers Handbook for further advice.

During spraying

  • Set the spray boom at the correct height and keep as low as possible without compromising the evenness of spray deposition. Check spray angles and adjust the height accordingly.
  • Watch for changes in the wind speed and direction; if necessary change your spray programme to avoid drift onto non-target areas or stop spraying until suitable conditions return.
  • Stay alert: ensure that spray is not allowed to drift onto non-target areas.
  • Maintain a constant speed and pressure, particularly if the sprayer is fitted with an automatic volume regulator. Small increases in the speed result in large increases in pressure.
  • When using a boom sprayer, reduce the operating pressure and forward speed but keep the dose, volume and spray quality within label recommendations.
  • Take advantage of the latest techniques to reduce spray drift. Use low pressure, low drift, angled nozzles, rotary atomisers, twin fluid atomisers and air assisted sleeve-boom sprayers where these are appropriate to the product being applied.

More advice

Wind speed guide

Approx. Airspeed at Boom height.

Beauford Scale (at ht 10m)

Description

Visible Signs

Spraying Advice

Less than 2 km/h

(< 1.2 mph)

Force 0 Calm Smoke rises vertically Use only medium or coarse spray quality
2.3 - 3.2 km/h

(1.2 - 2 mph)

Force 1 Light air Direction shown by smoke drift Acceptable spraying conditions
3.2 6.5 km/h

(2 4 mph)

Force 2 Light breeze Leaves rustle, wind felt on face Ideal spraying conditions
6.5 9.6. km/h

(4 6 mph)

Force 3 Gentle breeze Leaves and twigs in constant motion Increased risk of drift; take special care
9.6 14.5 km/h

(6 9 mph)

Force 4 Moderate Small branches moved, raises dust or loose paper Spraying inadvisable


This guide was produced by the Crop Protection Association.

April 2005

 

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