Bentazone
Updated August 2021
Protect water to keep bentazone as a weed control option Bentazone has been identified in official UK surveys as the approved herbicide with the most frequent exceedances of legal limits in groundwater, and is also increasingly found in surface water. Unless extreme care is taken to protect water from bentazone, there is a serious risk that its use may be restricted or lost. How does bentazone get to water • Bentazone is extremely soluble in water and highly mobile in soil. • All pathways matter. Bentazone may leach to groundwater on vulnerable soils. Surface water may be reached via drain flow, surface runoff or spray drift. How best to use this active • Avoid use of bentazone on soils vulnerable to groundwater leaching, e.g. - soils on chalk/limestone that are shallow (<30-35cm) and stony (>10% of surface area) - shallow (<30-35cm) soils on sandstone - soils with shallow groundwater (<1m below surface) - soils with low organic carbon content (<1% OC) • Do not apply if heavy rainfall is likely within 48 hours. • Avoid application when drains are flowing or likely to flow within 7 days. D o not apply in autumn/winter . Follow basic water protection advice • Point pollution sources (farmyard runoff, spillages) must be avoided. • 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.
New: High Risk Planning and Mapping Tool
Quickly and easily identify fields in HIGH RISK areas to avoid placing crops that may need bentazone in vulnerable fields, and to check field risk in season: https://bit.ly/BetterBentazoneTogether Reducing the risk • Do not apply more than 1000 g ai/ha/year • Do not use bentazone on:- - soils on chalk/limestone that are shallow (<30-35cm) and stony (>10% of surface area) - shallow (<30-35cm) soils on sandstone - soils with shallow groundwater (<1m below surface) - soils with low organic carbon (<1% OC) On other soils:-
• Always follow the advice on the left hand side of this sheet. • In addition, if at least 3 of the following criteria are met, then the risks to water will be significantly reduced:- 1. Heavy rainfall is unlikely within 48 hours 2. Field drains are not flowing and are unlikely to flow within 7 days of application 3. There are no field drains in the field 4. Field slope is less than 5% (a 5% gradient is 1m fall in 20m) 5. The field is not bordered by a watercourse 6. Application occurs in spring/summer after 1st April
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NEW - Visit the Better Bentazone Together webpage for more info: https://bit.ly/BetterBentazoneTogether
For further information visit www.voluntaryinitiative.org.uk
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