Kerb Weather Data – Report 1 – week ending 20 October 2017

Welcome to the first edition for this autumn giving timing advice for application to oilseed rape.

Soil temperatures (at 30 cms) in the oilseed rape growing areas are around 11°C – 14°C, too warm for outstanding results to be achieved with Kerb® Flo 500 for blackgrass control.  In northern England and Scotland soils are also very wet which would prohibit travelling anyway.

Please note a 30 cm soil temperature reading is less variable than the more commonly used 10 cm reading.

For optimal blackgrass control Dow AgroSciences recommend Kerb Flo 500 and ASTROKerb® applications are made when soil temperatures have got down to 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.

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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.

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