This gives timing advice for application to oilseed rape. (For beans, Kerb® Flo 500 must be applied within 7 days of drilling but before crop emergence).
Soil temperatures are cooling (at 30 cms) and are now around 10°C – 13°C, in the main oilseed rape growing areas. In Scotland and the North, applications are now being considered but in many areas soils are also very wet making application difficult. Further South, soils are still warm and are also dry – in the East particularly so. There is considerable risk to water if there is heavy rainfall within 48 hours after application to a dry soil, so caution is recommended. Too dry and propyzamide will not bind to the soil leaving it susceptible to leaching away in a high rainfall scenario and washing too deep into the soil past the rooting zone of the blackgrass.
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 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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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.
Download Topic Sheet 16 “Advice for Blackgrass Control in Oilseed Rape” for further advice.