Lesson 2 – Stewardship schemes

Stewardship guidelines

There is now a wide range of pesticide stewardship schemes in operation across the UK.

For further information the Voluntary Initiative hosts a full set of Water Protection Advice Sheets (WPAS) on its website HERE

The Voluntary Initiative logo

Metaldehyde Stewardship

From 31 March 2021 no further supplies from manufacturers were permitted but distributors could still sell stocks and use could continue until 31 March 2022. From 1 April 2022 it is now illegal to sell and use metaldehyde products.

Further information about metaldehyde and slug control using Integrated Pest Management methods can be found at GET PELLETWISE


Approval of the active ingredient carbetamide was not extended in 2021 and will not be available for use beyond 30th November 2022. Any unused products must be disposed of via a licensed waste disposal contractor.

OSR herbicides

The VI launched the ‘OSR herbicides? Think Water’ campaign to raise awareness of the concerns regarding the occurrence of five herbicide active ingredients that are being found in water: Propyzamide, metazachlor, quinmerac and clopyralid.

All are used on oilseed rape, typically aimed at the control of blackgrass, and are generally applied in the autumn. There is a chance that propyzamide products may be applied when drains are flowing or just about to.

The issue of metazachlor has also been highlighted in the ‘Metazachlor Matters’ stewardship guidelines by agrochemical manufacturers BASF and Adama, which now includes good practice stewardship advice for quinmerac.

Metazachlor and Quinmerac

  • Maximum dose – 750gm/ha metazachlor
  • Maximum Dose – 250gm/ha quinmerac
  • Undrained fields – no timing restrictions on last application
  • Drained fields (including temporary) – aim for 1st October application, cut-off date 15th October
  • Applications after 1st October can be made if soil/seed-bed conditions are good and drains not flowing
  • Drained fields in Drinking Water Safeguard Zones – cut-off 1st October.

Download the Metazachlor and Quinmerac Water Protection Advice Sheet HERE

spraying stubble

Propyzamide and Clopyralid

Action must be taken by those using products containing these active ingredients to prevent them entering watercourses to avoid the increasing restrictions on their use. Clopyralid is particularly difficult to remove from water.

  • Take care when filling and cleaning the sprayer
  • Use 6m grass buffer strip, or 5m no-spray zone, beside watercourses
  • Discuss cultivation and spray timing with your BASIS-registered adviser
  • Manage soils and tramlines to avoid surface run-off or erosion
  • Do not apply when soils are cracked, dry or saturated
  • Do not apply if heavy rainfall is expected within 48hr of application
  • Always check the required dose with your BASIS-registered adviser.

Water Protection Advice Sheets:

Click on the following links and ensure you read each advice sheet.




Bentazone is the active ingredient most often causing exceedances in ground water, due to the active being highly water-soluble and mobile in soil. It readily leaches down into groundwater, while surface waters can be contaminated by run-off and spray drift.

The VI updated its stewardship guidelines April 2019.

  • Avoid use of bentazone on soils vulnerable to groundwater leaching:
  1. Soils on chalk/limestone that are shallow (<30-35cm) and stony (>10% of surface area)
  2. Shallow (<30-35cm) soils on sandstone
  3. Soils with shallow groundwater (<1m below surface)
  4. Soils with low organic carbon content (<1% OC).
  • Do not apply if heavy rain is likely within 48 hours
  • Avoid application when drains are flowing or likely to flow within seven days
  • Reduce dose rates (<1,000gm ai/ha/year) as far as possible
  • Use bentazone as late as possible to reduce leaching probability, do not apply in autumn/winter
  • Follow basic water protection advice
  • Avoid point pollution sources (farmyard run-off, spillages)
  • Take care when filling and cleaning the sprayer
  • Use a minimum 6m grass buffer strip or 5m no-spray zone adjacent to watercourses
  • Do not apply if soils are dry, cracked or saturated.

Read the Bentazone Water Protection Advice Sheet HERE


The challenge with Clomazone is volatilisation after application, resulting in vapour drift from target areas onto neighbouring crops and non-target plants (hedgerows, etc), causing damage.

Products are formulated using encapsulation to help reduce volatility and off-target damage to sensitive plants.

Where non-target areas have become contaminated and the effects (bleaching) seen, they should be reported to the respective manufacturer.

Specific stewardship advice is available from the manufacturers of clomazone products.

Follow the links below to read up on each one:





Clomazone stewardship advises the use of drift reducing measures, which include:

  • Use a coarse spray quality and water volume of 200 – 400 litres/ha
  • Maintain the appropriate boom height and forward speed
  • Only spray when wind speeds are between 1.2 – 4mph (Force 1 to 2 according to the Beaufort scale, measured at 10m above ground)
  • DO NOT leave the sprayer standing overnight with content in the tank.

While individual formulations are designed to reduce the risk of off-target effects, under certain climatic conditions, i.e. hot and humid weather, clomazone has the potential to volatilise and some transient bleaching of non-target crops and other plant species could occur.

Generally warm temperatures and moist soil at or shortly after application, increase the potential for volatilisation.

Where non-target areas (neighbouring crops, hedgerows, etc) have become contaminated and the effects (bleaching) seen, they should be reported to the respective manufacturer.