This summer and autumn, there are several positives for oilseed rape growers. Rising prices, timely rainfall, an early cereal harvest, and reports of low cabbage stem flea beetle (CSFB) larvae, make oilseed rape one of the most profitable break crops.
While the benefits of growing oilseed rape are well known, the challenge of establishing the crop and supporting it through winter remains a consistent concern. Early weed control is one way to support the crop, but this must be balanced against the risk of upfront costs, especially given the uncertainties around establishment and early crop growth.
A Corteva survey in 2023 showed that many growers have moved away from pre-emergence herbicide strategies in favour of post-emergence sprays. Recent conversations with growers suggest this remains a common approach.
Delaying investment in weed control allows growers to assess crop establishment before deciding on further action. Controlling broad-leaved weeds in early autumn, once the crop is established, helps reduce competition and avoids the risk of delayed applications in November or December, when waterlogged soils can prevent sprayer access.
Corteva’s post-emergence, autumn-applied herbicide Belkar® offers effective control of key weeds from 1st September:
Flexible application timing: 1st September to end of December, from crop GS12
Key weeds controlled: Cranesbill, fumitory, poppies, cleavers, shepherd’s purse, mayweed, red dead-nettle and field pennycress
Active ingredients: Arylex™ active and picloram
Performance: Works well in variable temperatures and is rainfast in 1 hour
Compatibility: Mixes with a range of products, including Kerb® Flo 500 or Astrokerb®; no boron restriction
Crop safety: No following crop restrictions in a normal rotation
Corteva recommends three treatment options for best results:
Treatment Option |
Timing & Rate |
Notes |
|---|---|---|
0.25L/ha at GS12 |
At two true leaves |
Controls weeds germinated alongside the crop. May be sufficient before a later application of Astrokerb or Kerb Flo 500. |
0.25L/ha fb 0.25L/ha |
Second dose 2–4 weeks after first, in high weed pressure |
For further flushes of weeds. Alternatively, apply 0.5L/ha from GS16 when weeds are up to 5cm. |
0.5L/ha from GS16 |
At six true leaves, weeds 8–10cm |
Wait until all weeds have emerged, then apply to control weeds going into autumn/winter. |
Trials have shown that applying Belkar early (September) to remove the broad-leaved weed competition not only gives better control of weeds because they’re small, but also gives the crop a better chance at establishing. So it is a balance.
To find out more visit www.corteva.co.uk/belkar
Belkar (September application) followed by
Astrokerb (early December application).
No autumn weed control, no crop.
