2 June 1995



Industrial oilseed rape management comes under focus on the Association of Independent Crop Consultants stand at Cereals 95. Robert Harris relays the latest advice

COAXING a profit from industrial oilseed rape on set-aside demands high standards of management. Only then can the fine balance of producing good yields at minimum cost be struck.

So says Peter Taylor, an AICC agronomist for Bishops Stortford-based Samco. "You cant treat set-aside rape as a Cinderella crop and expect good returns." But too many growers have done that in the past, he adds. "They looked at the end price, stuck the seed in the ground and did nothing to it. Do that and you get nothing back."

Although double low industrial rape fetches about £130/t and high erucic acid rape (HEAR) £20 more, it is still worth less than conventional rape. That means it needs to be managed more carefully to optimise profits. "Each input must be justified," says Mr Taylor. He favours HEAR for its higher price. "Its worth more, and it yields as well and is agronomically similar to grow." Volunteers are the main drawback, he concedes.

"You cant mix the two. Dont grow double low rape on the rest of the farm – a few high erucic volunteers in a conventional crop will ruin it." The reverse can also be true, he warns.

Winter double low varieties remain the best choice for those unwilling to take that step. Although spring rape removes the pigeon problem and costs less to grow, the savings are not enough to offset the lower yield, Mr Taylor maintains. "Spring rape is also quite drought-prone and clashes with wheat harvest."

Growers should select a variety that is cheap to grow. Express does well in his area. "It has good disease resistance, stands well and yields." HEAR growers have little choice – Martina is the main variety on contract, he says.

Cheap seed

Farm-saved seed is worth considering, says Mr Taylor. It costs about £1.50/kg dressed and cleaned; buying in seed is 3-4 times more expensive. "You can save £20/ha (£8/acre) before you even start." Find the cheapest dressing possible, he adds. "You only want something to control early flea beetle attack."

Seed should be drilled in the last 10 days of August for quick establishment and to produce plants with 6-7 leaves going into winter. That means fewer winter losses and also helps cut pigeon damage.

A quick turnaround after the previous straw crop is therefore vital. Discing is the best option on heavy soils – two or three passes will incorporate well-chopped straw to 10cm (4in). Ploughing and furrow pressing is often enough on lighter soils to create a seedbed.

Mr Taylor bases broad-leaved weed control on trifluralin. Cleavers must be treated elsewhere in the rotation – they are too expensive to control in set-aside rape, he advises. Ideally trifluralin needs incorporating before drilling, but the action of the drill alone can give good results, he adds.

Drilling rate

The aim is to sow 100 seeds/sq m for a good crop. Seed weight differs between varieties, so it helps to know the thousand grain weight. "But as a rule of thumb, on heavy land dont sow less than 5kg/ha."

A maintenance P and K dressing will be needed – the crop removes about 60kg/ha (48 units/acre) of each. But autumn nitrogen should be avoided unless there is excess straw, when 40-60kg/ha (32-48 units/acre) may be needed to counter bacterial lockup. "But ploughing releases nitrogen, so I would not apply it then," notes Mr Taylor.

Further autumn treatments should only be applied as and when needed. Flea beetles may need controlling, and grass weeds should be sprayed with the lowest effective dose. Where germination is likely to be prolonged, a quarter or third rate early spray should be applied, followed by a similar later application as necessary.

Autumn fungicides should not be needed if resistant varieties are grown. Only high levels of light leaf spot justify the £12/ha (£4.80/acre) spray cost, he reckons.

Light leaf spot

The disease is more important in the spring, he maintains. "If light leaf spot is coming in on the older leaves, a half-rate triazole should be enough to control it."

Growers with taller varieties can take advantage of tebuconazoles (Folicur) growth regulatory activity by applying a low "holding" dose to check disease, then spraying again with a half rate + chlormequat at green bud, advises Mr Taylor. Pollen beetles can trouble winter rape, he adds. "But only spray if 5-10 beetles/a plant can be found at green bud – once flowers are open, the danger is past."

Avoid Sclerotinia

Mid-flower is the only time Mr Taylor recommends routine spraying. Sclerotinia can hit yield hard, and an attack is not worth risking, he warns. In most cases 1l/ha (0.7pt/acre) of carbendazim is adequate and cheap at £6/ha (£2.40/acre). It also controls botrytis.

In high risk cases, a half-rate vinclozolin (Ronilan) may be needed, but it trebles the cost. Alpha-cypermethrin (Acquit, Contest, Fastac) can be added if weevils can be found across the field, but is unnecessary if they are confined to headlands.

A late Alternaria spray is not usually needed, he suggests. High clearance tackle adds to the expense, so the cost will only be recouped if the disease is moving up the plant during wet weather.

Keeping control of inputs in this way means the crop can pay its way (see box), says Mr Taylor. "Those who were put off the crop should reconsider it. Its a good way of spreading fixed costs, provided you can do it using existing labour and machinery. But you have to treat it as a worthwhile crop to get the best from it."

Typical industrial oilseed rape gross margins (£/ha)

OO winterHEARNatural regeneration

Yield (t/ha)3.22.95 –

Price (£/t)130150-





Variable cost18818825

Area payment315315315

Gross margin543570290