With much of the UK experiencing exceptionally dry conditions, successful establishment of oilseed rape will be determined far more by soil moisture availability than by calendar date, says Corteva Agriscience.

"After the extreme heat and drought that we've seen up and down the country, and while many fields are cleared and ready to drill, sowing into dry seedbeds can lead to uneven germination, patchy emergence and reduced crop vigour, leaving plants more vulnerable to cabbage stem flea beetle, slugs and weed competition," says Hugh Guinan, Corteva Field Technical Manager.

"While waiting for rain can be frustrating, when it does arrive, the conditions are great for oilseed rape, and experience continues to show that some of the highest yielding crops are established later in the season, often well into mid-September, when conditions are favourable."

Oilseed rape remains one of the most valuable and profitable break crops in the rotation, delivering strong financial returns while providing important agronomic benefits.

Commodity markets are also strong for the crop, as uncertainty in Europe and the Middle East continue to buoy oilseed rape prices, with ex-farm prices averaging £423/t.

The crop offers an opportunity to tackle resistant grassweeds, reduce weed burdens ahead of cereals and improve rotational performance. However, achieving its full potential starts with establishing a strong, even crop. Oilseed rape is not resilient and requires careful management in its early stages to establish.

For successful establishment, oilseed rape requires moisture, light, nutrition, space and suitable temperatures to grow. Encouragingly, soil temperatures remain well above average across many regions, supporting rapid growth and extending the potential drilling window.

"In many situations, growers already have the space, light and temperature required. Moisture, however, remains the limiting factor," says Hugh. "Attention should instead be placed on the factors that can be controlled – variety selection, alleviating compaction, seed-to-soil contact, placing seed at 2-3cm depth, ensuring adequate nutrition, and conserving moisture."

Oilseed rape remains a vital crop in the rotation for weed control. It's therefore key to build robust herbicide programmes whilst also supporting crop growth at key timings. 

"Drilling date, establishment method, and cultivation strategy all influence weed populations," says Hugh. "The timing, depth and frequency of cultivations can affect both the composition and density of weed species present. Where possible, start with a clean seedbed and target both grass weeds and broad-leaved weeds carried over from the previous crop."

Weed control decisions once the crop is drilled are often balanced against the uncertainties of establishment. As a result, many growers have moved away from traditional pre-emergence herbicide programmes and instead favour post-emergence approaches. This strategy allows crop emergence to be assessed before further investment is committed.

Weed control in early autumn is important in oilseed rape because the crop is relatively uncompetitive during its early growth stages. Minimising weed competition during these early stages is critical to a successful crop by helping plants root strongly, grow rapidly and make the most efficient use of available resources, as well as giving plants the best opportunity to achieve rapid, even establishment and develop a robust canopy.

When conditions favour oilseed rape establishment, they also favour weed germination. Regular crop monitoring is therefore essential to identify emerging weeds and apply treatments before they become difficult to control. Controlling weeds early in the programme is often more cost effective and beneficial to the crop.

Companion crops can play a valuable role in oilseed rape establishment, helping to suppress blackgrass while delivering wider agronomic benefits such as improved soil health, crop nutrition, pest management and support for beneficial insects.

However, companion crops should complement, not replace, a robust herbicide programme. Herbicide strategies should be tailored to the weed spectrum, companion crop species, and intended lifespan within the crop.

Belkar herbicide offers flexibility in both rate and timing, allowing growers to assess crop establishment before making weed control decisions. This enables applications to be tailored to individual field conditions, maximizing flexibility while maintaining high levels of weed control efficacy. 

 "Belkar significantly reduces risk, by avoiding the use of residual herbicides, but instead controls weeds once the crop has germinated and any impact from cabbage stem flea beetle has been assessed. Belkar works independently of soil moisture and environmental conditions." says Hugh.

Belkar also provides control of a wide range of competitive broad-leaved weeds, including cleavers, cranesbill, poppy, fumitory, shepherd's purse and mayweed.

Belkar can be applied from the two- to four-true-leaf stage as a single application, a sequence of applications, or as a later higher-rate treatment to suit crop development and weed pressure.

Trials have demonstrated that earlier applications of Belkar, typically during September, not only improve weed control by targeting smaller weeds but also reduce competition during the critical establishment phase, helping crops achieve stronger growth before winter.

Belkar can be followed with Astrokerb or Kerb Flo 500 to complete the programme by controlling blackgrass, ryegrass and other grassweeds later in the autumn. For more information, get in touch with the Corteva Technical Hotline at ukhotline@corteva.com or call 0800 689 8899

Visit Corteva's OSR hub for product information and resources at https://www.corteva.com/uk/crops/oilseed-rape.html