Propyzamide stewardship

Sprayer in OSR field

Guidelines and advice

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Oilseed rape is an integral part of the UK arable rotation, and a profitable break crop. 

Renowned herbicides such as Astrokerb® and Kerb® Flo 500 contain propyzamide and are the cornerstones of many herbicide programmes. They are key to controlling grassweeds, especially blackgrass and ryegrass in oilseed rape, and with no known resistance, propyzamide can help manage and reduce the burden of these weeds across the rotation. 

After a heavy rain event there is a risk of propyzamide attached to soil particles getting washed into surface water. Appropriate planning, management and adoption of stewardship practices must be followed to mitigate this risk.

Oilseed rape growers are urged to consider the actions they can take to protect watercourses.

Field selection, tramline placement and buffer zones can all play an important role in effective risk mitigation.

In line with best practice guidance from the Voluntary Initiative, growers are advised to implement simple steps which will help ensure autumn and winter-applied products don’t reach watercourses. 

You can also speak to your agronomist, your local Catchment Sensitive Farming Officer or your local catchment water company officer for advice on managing the reduction of pesticides reaching water. 

Before drilling and at establishment

1. Aim to grow oilseed rape on low-risk fields:​

  • Those that don’t slope to a watercourse (field slope is less than 5% (1m fall in 20m)​).
  • Are less susceptible to run-off​.
  • Are NOT bordered by a watercourse​.
  • There are NO field drains​.
  • The field has NOT been deep sub-soiled (below plough layer) or mole-drained within the preceding 6 months. 

2. Consider appropriate establishment, direction of working travel, soil type and topography

  • Layout tramlines so that they do not provide a direct route for water to leave the field.

  • Disturb the surface compaction in the tramlines if possible. ​

  • Ideally establish the crop with true minimum tillage working the top 4-6cm only or by direct drilling.​

3. Use buffer zones ​

  • To reduce the risk of run-off (both water and sediment), that may contain pesticides from reaching water courses, the VI guidelines recommend a 6m buffer along watercourses if possible. ​

  • Wide buffers are advisable in particularly vulnerable areas. ​

4. Safeguard zones ​

  • Refer to the Environment Agency website “Drinking Water Protected Areas Safeguard Zones (SgZs)” to check if planned oilseed rape fields are in a Safeguard Zone. Consider not growing this crop if mitigation methods cannot be put in place and there is a high risk of herbicides moving into water.

    Check for Drinking Water Safeguard Zones and NVZs (

At application

1. Take care when filling and cleaning the sprayer to avoid a point source contamination scenario. ​

2. Check soils – do not apply propyzamide when soils are cracked, dry or saturated. ​

3. Check the weather – do not apply propyzamide if heavy rainfall is expected within 48 hours of application. ​

  • Check Kerb Weather Data to use the traffic light system which indicates when weather conditions are optimum for Astrokerb or Kerb Flo 500 applications. 

4. Best use of propyzamide 

  • Propyzamide works best when applied to cold, moist soils, but this must be balanced with the need to protect water. ​

  • Apply at the right time – From 3 leaf stage of the crop (1st October) up to before 1st  February – Find out more about the best time to apply with our propyzamide back to basics webpage.

  • Apply when conditions are right – ​

    • Moisture – soils should be at 80% field capacity (1-2.5cm of moisture). ​

    • Soil temperature – at 30cm, maximum 10°C and declining. ​

    • Use the right dose rate – only use the maximum rate of 840gai/ha for severe blackgrass situations. 750gai/ha or 500gai/ha are recommended for less severe blackgrass or other grasses and broad-leaved weeds (see product label for details).  Only use one product containing propyzamide per crop per year. ​

Propyzamide information

Everything you need to know about propyzamide

Visit the Propyzamide back to basics webpage to learn about the active ingredient and best practice guidelines.

Further reading

Voluntary Initiative stewardship scheme

OSR Herbicides? Think Water!” The VI is working with water companies and the farming and crop protection industry to raise awareness of the issue, improve practices and develop new tools that will support farmers in continuing their responsible use of these herbicides/

You can also download the propyzamide advice sheet from the Voluntary Initiative here.

Is your land at risk of propyzamide reaching surface water?

Check if your location is a Drinking Water Protected Areas Safeguard Zones on the Environment Agency’s ‘Check Zones’ website.

Kerb Weather Data tool

Access Corteva Agriscience™ Kerb Weather Data tool

The Kerb Weather Data tool is meant to be used as a guide to local weather conditions to aid growers and advisors in making local tactical decisions to optimise their Astrokerb® and Kerb® Flo 500 applications and thus their activity against blackgrass. Kerb Weather Data (KWD) is available from mid-October to 31 January each year. Find out more here