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This post-emergence herbicide window will be crucial for oilseed rape growers

A lot of arable farmers will be glad to see the back of the last growing season and will be looking forward to a fresh start.

Every year we are reminded of how volatile the business of producing food is, and the past 12 months have been no exception.

A washout winter followed by a spring heatwave was just another example of the abnormal becoming the new normal.

For those upon whom the weather gods were smiling, most winter cereals were harvested early and cleared a path for oilseed rape to be drilled in late July and early August.

If the rain came, seed will have found moisture and we have seen some good crops emerging and establishing around the country. Good establishment has always been vital, but with the threat of cabbage stem flea beetle, getting a crop up and away has taken on renewed importance.

Where drills were kept close behind the combine, no pre-emergence herbicide was applied, so it will be important to take advantage of the current favourable conditions to control any flushes of weeds that could compete with the oilseed rape going into the winter.

The main focus will be hitting cleavers, poppy, shepherd’s purse, fumitory and cranesbill while they are small and easier to control. Because of this, having Belkar® in the armoury is becoming really important. It contains Arylex™ Active and picloram and is now in its second year of use in the UK and Ireland so we’re starting to get a picture of how it is able to help managing the risk and volatility that all farmers are experiencing – particularly oilseed rape growers.

The way we grow the crop is changing to favour a post-emergence approach to herbicides. This allows farmers to delay their herbicide investment so they can judge the quality of the crop and the weeds present before spraying any products.

The spray period for Belkar opened on 1 September and extends right up to the end of December, and there are three treatment options that we recommend oilseed rape growers to consider.

From four leaves, an application at 0.25l/ha will take out the weeds which have germinated alongside the crop and, in some circumstances, that may be enough broad-leaved control before an application of Astrokerb® (propyzamide + aminopyralid) or Kerb® Flo 500 later on.

In high weed pressure situations where there is a further flush of weeds, crops can have a second dose at 0.25l/ha two to four weeks after the first.

A third option to be used is to wait until six true leaves of the crop and all the weeds have emerged and apply 0.5l/ha which will take care of the weeds going in to the autumn.

We believe oilseed rape is too important and too valuable to UK arable businesses. Those that grow it will remain committed to finding an establishment strategy that works for them.

In tandem with the innovations coming out of our seed-breeding brand, Pioneer, we will certainly be there to help our customers find the solutions they need.

Image: John Sellars at OSR drilling in Oxfordshire, 21 August 2020.