Kerb Weather Data – First Report – week ending 14th October 2016

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. Soils are also dry in many areas.

Please note a 30 cms 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?
Propyzamide, the active ingredient in Kerb Flo 500, in common with other residual herbicides breaks down quickly in warm soils. If you treat now, it is likely the speed of breakdown will lead to insufficient concentration of propyzamide in the rooting zone of the blackgrass, inevitably leading to poorer levels of control. This advice has been proven in extensive trials over many variable autumns. Similar advice would apply to ASTROKerb.

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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