Welcome to the first edition for this autumn, providing timing guidance for propyzamide applications to oilseed rape.
Overall soil temperatures (at 30 cms) in oilseed rape growing areas are around 11°C – 13°C but falling rapidly due to the recent cold weather, too warm for outstanding results to be achieved with Kerb® Flo 500 or AstroKerb® for blackgrass control. In northern England (and Scotland) soil temperatures are cooler (nearer 10°C) but with milder weather forecast at the weekend soil temperatures are generally sub optimal for effective propyzamide applications. Soils usually become suitable for Kerb Flo 500 and AstroKerb applications around the 10th November based on previous years so we would expect recommendations to be made imminently.
Use the map and links below to find the data for soil temperatures and moisture-deficits in your region. Please note at 30 cms soil temperature reading is less variable than the more commonly used 10 cm reading.
Whilst overall conditions across the UK may not be currently suitable for Kerb (or ASTROKerb) applications, you can check your local status using the postcode checker for a more accurate reading.
For optimal blackgrass control Corteva Agriscience recommend Kerb Flo 500 and ASTROKerb® applications are made when soil temperatures are 10°C and falling, and there is sufficient soil moisture in the soil for grassweed uptake. Both these criteria are rarely met before November.
More Kerb Weather Data will be supplied as the season progresses.
Check out application conditions for your local postcode
Simply enter your postcode in the banner and click GO to view the results.
Why does Kerb work best when soils are cooler?
To optimize the blackgrass control activity from your ASTROKerb or Kerb Flo 500 application, ensure that propyzamide (the active ingredient in both these products) is in contact with the blackgrass roots for as long as possible. Soil temperature plays an important role to achieve this.
Cooler soil temperatures slows propyzamide breakdown and ensures blackgrass roots can take up propyzamide for a longer period of time, thus optimizing weed control. The graph below shows how soil temperature can affect propyzamide half-life.
What can I add to the Kerb programme to improve blackgrass control?
With high populations of blackgrass the use of programmes to give control is increasingly vital. Adding a “fop or dim” with good blackgrass activity as a sequence or tank-mix in the programme nearly always improves control and is frequently better than carbetamide/propyzamide programmes.
Download Topic Sheet 16 “Advice for Blackgrass Control in Oilseed Rape” for further advice.