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Growers who held off planting oilseed rape last month can still expect decent yields – even if they delay drilling until mid-September, say agronomists.

• Moisture vital for establishment 

• Lack of any rain delays planting

• Still time to get crops in ground

Growers who held off planting oilseed rape last month can still expect decent yields – even if they delay drilling until mid-September, say agronomists.

Earlier this year, United Oilseeds forecast a 30% increase in the amount of rape planted this summer. But the area hangs in the balance after the heatwave and summer drought left soils parched and dusty.

“I need between 25 and 50 millilitres of rainfall before I can confidently drill oilseed rape,” says Michael Wilton, farm manager at the Stody Estate in north Norfolk.

“Moisture is the most important aspect of establishing the crop – it’s as important as all the other factors – cultivations, varietal selection, early nutrition – put together. Not only do we need some moisture for seeds to chit, we need enough to keep seedlings growing.”

BASF agronomy manager Matt Keane, agrees: “If there’s no moisture in the ground, emergence will be patchy, and flea beetle will move from one plant to another. It will also slow plant development, making them even more susceptible to damage.

Wait for moisture

“It’s worthwhile holding off until there’s some moisture, otherwise all that vigour the effort and hard work getting a crop to grow, goes to waste. There’s nothing flea beetles like more than the cotyledons of rape.”

Mr Wilton would usually receive 400ml of rainfall by August. This year he was 160ml short. “I’ve been asked whether I’d consider irrigation to get rape established. It’s always been a resounding ‘no’ but I’m starting to wonder whether I ought to contemplate it.”

Last year, Mr Wilton drilled rape from 10 August to 10 September. With half of the seed still in the shed, he was understandably keen to get going this year. But moisture, he says, is more important than drilling date.

When it comes to irrigation, he says: “Despite having had 100 million gallons of water from the reservoirs and bole holes, it’s likely that I’ll have run out of water by the time any rape is in the ground.”


The early crop last year and was well-established by the time there was activity from cabbage stem flea beetle. There were more larvae come spring, but by then the plants were big enough to withstand the damage.

“The later drilled crops didn’t come under flea beetle pressure, but the mid-drillings went in when it was drier and didn’t establish well, the beetles were active.”

Due to the soil type, cultivations are really important on Mr Wilton’s farm: It is critical that rape roots are unimpeded, he says. 

A big tap root needs to go down for anchorage, as well as to access water and nutrition.

Varietal choice also plays a key role. This year, Mr Wilton is growing DK Expansion, LG Ambassador and V367OL (HOLL). He says he looks for good genetics, strong autumn vigour and big seed. “I won’t accept seed with less than a 5g thousand seed weight.

Quite simply we’ve found that the bigger the seed, the bigger the cotyledons and the more energy the young plants have, making them more resilient to CSFB damage. A good seed treatment is important too.”

Mr Keane agrees: “Seed treatments help plants get up and away.

“Integral Pro, for example, is a bio-fungicide based on the bacteria Bacillus Amyloquefaciens and activates plant’s natural defence systems. 

It colonises the roots, protecting the plants from various attacks, acting as a barrier against fungi.”

At drilling, Mr Wilton uses a starter fertiliser. He also recommends good soil to seed contact and early weed control is preferable.

“In 2020, we did a pre-emergence application of clomazone to clear up various weeds.

“In 2021, it was drier and we weren’t sure how successful the crop was going to be so we decided not to apply any pre-em herbicides. I felt that was a mistake.

“Weed control is a real challenge,” he admits.  “We’re upping the pre-establishment spend and increasing the risk early on.

“However, we need to set ourselves up to succeed so we need to do what’s necessary.”