Stewardship tools enhanced as farmers prepare for propyzamide applications

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Significant upgrades to Corteva Agriscience’s Kerb Weather Data tool will help growers and advisers be even more precise when timing oilseed rape herbicide applications this winter.

The data is relied upon by growers across the UK to identify the best time to apply AstroKerb® or Kerb® Flo 500, which typically takes place from early November.

The weather data’s simple traffic light system has guided application advice for years, but a step change for 2021 sees new functionality brought in on the Corteva Arable App.

Not only will the development ensure well-timed applications for robust control of grassweeds and some broadleaf weeds, but it will help the industry achieve an even higher level of product stewardship by helping identify and reduce the risk of active ingredients running off the field.

Individual fields can now be pin pointed to see if conditions are suitable for herbicide applications, building additional accuracy on top of the postcode search function.

The slope of the field – a factor of significant importance when mitigating run off – can also be determined. An indication of soil type is also built in. At the click of a button, growers and advisers can manually add water boundaries to individual fields.

Applications from around 5 November

Products containing propyzamide such as Kerb Flo 500 and AstroKerb can be applied to oilseed rape now, providing the crop has at least three leaves.

However, to make sure the activity of these herbicides is optimised against blackgrass and other grass weeds, soil temperatures should be 10°C and falling while soil moisture should be sufficient but not saturated.

“From experience and under normal circumstances, conditions for propyzamide usually become suitable for applications from around 5 November so farmers will be preparing to spray now,” says John Sellars, Oilseed Rape herbicides manager for Corteva.

“Not only will Kerb Weather Data help determine the best time to apply Kerb Flo 500 and AstroKerb to get the best weed control, it also helps fulfil stewardship obligations to help growers and advisors identify and mitigate the risk of herbicide run-off.”

Farmers and advisors can access the basic traffic light tool at, but are encouraged to download the Corteva Arable App to access this improved functionality.

Stewardship resonsibility

Applications should be delayed if field drains are running, or if significant rainfall is forecast in the coming 48 hours. Ideally any fields with a gradient towards a watercourse should have a grass buffer strip of at least six metres established. Where gradients are more severe, the grass buffer strip should be wider. Corteva has launched a useful propyzamide stewardship webpage to provide additional resources for farmers and advisors which can be accessed at

“We take our stewardship responsibilities seriously and hopefully this tool will help growers and advisors to manage their grassweeds better and help identify and mitigate the risk of applications to the environment,” Mr Sellars says.

“Both products deliver strong grassweed control and are the benchmark solutions for blackgrass control in oilseed rape. AstroKerb also delivers a wider broadleaf weed spectrum that includes key weeds such as poppy and mayweed,” Mr Sellars says. “We would expect activity on sow thistle and groundsel too.

“Grassweeds such as blackgrass and ryegrass are difficult to control in cereals and one of the benefits of growing oilseed rape is that blackgrass populations can be reduced. If Kerb and AstroKerb are given the best conditions to work they can give levels of control of over 90%, a level that is almost unprecedented with other graminicides in cereals nowadays,” he says.


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About Author

Editor of Agronomist and Arable Farmer as well as responsibility for the Agronomist and Arable Farmer and Farm Business websites. After 17 years milking cows on the family farm John started writing about agriculture in 1998 and has since written for a variety of publications and has developed a wide circle of contacts within the industry. When not working John is an avid follower of Stoke City.