Kerb Weather Data – Report 3 – week ending 23 November 2018

Welcome to the third edition for this autumn, providing timing guidance for propyzamide applications to oilseed rape.

Soil temperatures (at 30 cm) have cooled to less than 10°C in the main oilseed rape growing areas which means we are now entering a window in which conditions are ideal for propyzamide application. We would be expecting to see applications being made in the coming days where conditions allow. With rainfall forecast in some areas we advise users to be cautious as there is an increased risk to water if there is heavy rainfall 48 hours after application to a dry soil. Where applications are made to dry soils the propyzamide does not bind to the soil leaving it susceptible to leaching.

It is important to wait until soil temperatures have cooled to less than 10°C as this optimises the blackgrass control activity from your propyzamide application. Cooler soil temperatures slows propyzamide breakdown and ensures blackgrass roots are exposed to propyzamide for longer periods of time, thus optimizing control.

Use the maps 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.

KWD map week ending 23 November 2018


Whilst overall conditions across the UK may not be currently suitable for Kerb® (or ASTROKerb®) applications, please 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.

More Kerb Weather Data will be supplied as the season progresses.

Check out application conditions for your local postcode

KWDClick on the link to the left to use the postcode checker.

Simply enter your postcode in the banner and click GO to view the results.










Please ensure good practice when using Kerb Flo 500 or ASTROKerb to avoid restrictions on these products


Will large crop canopies interfere with blackgrass control?

Trials have shown that even where canopies are dense, excellent blackgrass control can be achieved once optimum soil conditions are met.

As ASTROKerb will mainly be used for blackgrass, this should drive application timing. ASTROKerb has both contact and root activity on poppies and mayweeds and in our extensive trials programme, when optimally timed for blackgrass control even where canopies were large, control of these broad-leaved weeds has been good. Where broad-leaved weeds are the sole driver an earlier application could be considered before broad-leaved weeds become too large.

 Can I apply Kerb Flo 500 in a frost?

Kerb Flo 500 may be applied in frosty conditions but avoid application onto frozen ground where subsequent rainfall could result in run-off into watercourses.

For ASTROKerb please ensure frost is off the target broad-leaved weed.


Download Topic Sheet 16 “Advice for Blackgrass Control in Oilseed Rape” for further advice.