“Know The Bentazone Risk” - Water Stewardship

Environment Agency data shows that Bentazone (the herbicide active substance in Basagran® SG and other products) is the most commonly detected approved pesticide in UK groundwater. It’s also increasingly being found in surface water. Due to EU legislation on pesticides and water, it is possible that the approval for Bentazone will not be renewed, resulting in the loss of all Bentazone products.

'Know The Bentazone Risk' is a cross-industry programme, aimed at promoting sustainable water stewardship on farms. It includes events, on-farm engagement and the development of management tools, including the new Crop Planning and Bentazone IPM Tool.

north_east Check your risk: Use the quick and easy mapping and planning tool to see if your farm is in a high-risk area or has vulnerable soils.

Following use of the risk mapping tool by growers since its launch in 2021, feedback has helped improve the tool for 2025. Updates include:

• A simplified interface

• More IPM guidance

• Features to evidence decisions taken

The use of this Crop Planning and Bentazone IPM Tool has been developed to support water stewardship initiatives while promoting responsible and sustainable product use.

For maximum value, the tool should be used during rotation planning to avoid sowing legume crops on the most at-risk fields and hence avoid the use of Bentazone. Bentazone is highly soluble in water and very mobile in soil which has resulted in it being detected in both ground and surface water​​​.

It’s also worth checking in-season before spraying Bentazone.

Top tips to reduce the risk of Bentazone entering surface and ground water

1. Ensure the field is suitable before planting the crops

• Shallow, stony soils on chalk or limestone, and sandstone allow water to move more readily taking the chemistry with it. Likewise, low organic carbon soils are a challenge as there is less to bind the soil and chemistry together.

2. Avoid high-risk fields

• north_east Use the “Know the Bentazone Risk” mapping and planning tool.
• Bentazone is highly soluble and very mobile within soils.

3. Consider how and where you fill the sprayer

• Take care when handling the product, filling and cleaning the sprayer to avoid any leaks or spills.

4. Consider the weather

• Do not spray if >5mm rain forecast in the 48 hours post application, or if drains are running (fields with a shallow water table are to be avoided).

5. No spray zones

• Have a 5m no spray vegetative strip or 6m buffer strip against any areas of surface water.