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There are many factors to consider when establishing a crop of oilseed rape. David Langton from Masstock Arable picks out the main points.

A simple blueprint for establishing oilseed rape is impossible.The crucial thing to remember is that the most important day in the crop’s life is the day of drilling, so be prepared to make decisions based on the conditions.

Target population

Before winter sets in you should have large deep-rooted robust plants achieving good ground cover to capture light. You should also have good soil structure allowing effective drainage. Your crop will be

• More rapidly slug tolerant
• More phoma tolerant
• More difficult for pigeons to land in
• More competitive with weeds.

Target spring population is 20-40 plants/sq m with larger biomass types at the lower end of the range. The sowing rate to achieve this will typically be 40-80 seeds/sq m, the final decision being made on the day of drilling based on seed-bed conditions. Always calculate the rate by seeds/sq m (not kg/ha) as thousand seed weights vary enormously.

Drilling date and variety choice

Target drilling date is mid-August through to early September, although in the north of England and Scotland aim for August drilling. The aim is to have robust plants going into winter with big roots, and earlier drilling is much more likely to achieve this. However, many crops are established after winter wheat which often pushes the drilling date later.

There are excellent trials data showing improved establishment and crop performance of fast-developing hybrids like Excalibur, Excel and Hammer at later drillings compared to conventional varieties. Slower-developing varieties like Castille, Es Astrid and the hybrid Flash need drilling earlier to get the best from them.

Cultivation and drilling

• Winter rape is lazy rooting so make sure subsoil structure is good to allow the roots to grow down and to permit drainage. Assess soil structure by digging holes and deal with compaction if required.
• The very small seed requires a tilth fine enough to achieve good seed/soil contact. Drilling depth is 15-25mm. Rolling is essential.

Bearing these points in mind, the crop can be established by a range of methods. Attention to detail on how the machinery is set up and used for the field conditions on the day is critical. Under dry conditions moisture conservation is a prime consideration, particularly on heavy soils.

Soil type and seed-bed have a big influence on establishment. Heavy soils present more challenges where a finer tilth is required for the same soil moisture content to allow seed germination. Cloddy seed-beds will dry out faster, due to more air movement, and will increase slug pressure significantly.

Previous herbicide use may determine cultivation needs. For example, if Atlantis, Pacifica or Othello have been applied after 1 February, land must be ploughed (or heavy cultivated to at least 15cm) before drilling rape.

Seedbed nutrition

Oilseed rape puts on a lot of growth pre-winter and has a high nutritional demand – much greater than cereals. Where soil indices of P, K or Mg are low, apply fertiliser to the seed-bed and ensure it is mixed in to maximise nutrient availability to the plant as it establishes. Seed-bed nitrogen may be needed to help get the crop away, particularly with later drilling or where straw has been incorporated. Apply up to 30kg/ha of N either in the seed-bed or by very early establishment.

Tiger 90 mini prills can be mixed with the seed to bulk up low rates. They acidify the root zone increasing micro-nutrient availability as well as supplying some of the crop’s sulphur requirement.

Pest management

Two new insecticide seed dressings offer enhanced control of a range of insect pests over Chinook.

• Modesto – cabbage stem flea beetle, turnip sawfly, aphids (which can carry turnip yellows virus) and cabbage root fly.
• Cruiser – cabbage stem flea beetle and flea beetle.

Seed treated with either Chinook, Cruiser or Modesto must not be left on the surface, but covered with soil to protect birds, game and other wildlife. It is a statutory condition of using these products.

Slugs are a regular threat to establishment – the plants have such small energy reserves it does not take much damage to finish them off. Take special care to apply pellets, when required, safely to minimise the risk of them entering watercourses.

Weed management

There is a limited range of herbicides available for winter oilseed rape and the loss of trifluralin will make controlling poppies, chickweed, speedwells and blackgrass harder.

For many weeds, the best control will be achieved by starting with a pre or very early post-emergence metazachlor-based herbicide like Katamaran Turbo, but high rates need to be applied to achieve effective control. Where seed is not covered by 15mm of settled soil or on light soils if heavy rain expected, early post-emergence application will be safer.

Centium pre-emergence can be an effective addition particularly providing control of cleavers, hedge mustard, shepherd’s purse and chickweed, but needs a covering of 20mm of settled soil.

Early control of cereal volunteers with a graminicide is essential to avoid crop competition and moisture loss.

Effective weed control is influenced by establishment technique – are you moving the whole soil surface? A competitive crop will help achieve effective weed control.