After the 1st of October, theoretically you can start applications of propyzamide (such as Kerb Flo 500 and ASTROKerb) in oilseed rape according to their labels, but practically this active ingredient with residual activity, should only be applied when conditions are correct to optimize its performance. For that you need to wait until the soil temperature has gone below 10°C and is still falling and soil moisture is sufficient.
For the 2018 Kerb Weather Data service please click here
Temperature and soil moisture are critical to getting the best performance from Dow AgroSciences’ two leading oilseed rape herbicides – Kerb® Flo 500 and ASTROKerb®. The Dow AgroSciences’ postcode checker as seen here is an online tool that will help decide when it is time to spray. It could not be simpler, type in your postcode and the result appears as a traffic light : Red means wait; Amber means get ready and Green means consider going. It is rare that you will get a green light before November, but as both products can be used up to January 31st, there is no rush.