OSR acreage hangs in the balance

10 Aug 2022

Earlier this year United Oilseeds forecast the OSR area to increase by 30% in 2022 and while there’s no shortage of enthusiasm for the crop, many growers are waiting for rainfall. With little predicted for the South East, the acreage hangs in the balance.

“I need between 25 and 50ml of rainfall before I can confidently drill OSR,” explains Michael Wilton, farm manager at the Stody Estate in Norfolk and BASF Real Results grower.

“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.”

Based in Suffolk, 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.

“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 OSR.”

While growers have been able to start drilling further north, fear of another dry spell is still in the back of minds.

“In comparison with Mike, we’ve had a splash more rain to end a dry July,” notes Mat Barnes, BASF’s Agronomy Manager covering Yorkshire. “It was drizzily on and off all last week, preventing the combines from running. But a dry spell is set to come in and any OSR that’s been drilled could be vulnerable. Cabbage root fly and clubroot have all increased recently so it’s a watch out for drilling this early even with sufficient moisture.

“While CSFB pressure has lessened recently, pigeons are still a real issue and can take a good crop back to bare stems in no time. Getting a well-established even crop going into the winter is key as backward crops have landing spaces and are targeted first.”

Mike would usually receive 400ml of rainfall by August, but is currently 160ml short.

“At this moment in time, I don’t know where that moisture is coming from. If we’ve not had any significant rainfall by the end of August, I won’t be planting any OSR and that would be a disaster.

“I’ve been asked whether I’d consider irrigation to get the OSR established. It’s always been a resounding ‘no’ but I’m starting to wonder whether I ought to contemplate it. If I’d already cultivated, drilled and applied my pre-emergence herbicide, perhaps it’s not such a crazy idea to protect the investment afterall. It would still be expensive. This year, however, 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 OSR is in the ground.”

With half of the seed in the shed, Mike is understandably keen to get going but moisture, he says, is more important that drilling date.

“Last year we drilled OSR from 10th August through to 10th September. The early crop got away and was well established by the time we saw CSFB activity. Admittedly, it had 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 Mike’s farm: “It’s critical that OSR has unimpeded root development. It’s a big tap root which needs to go down for anchorage, as well as to access water and nutrition. It also helps keep soils well-structured within the rotation. Here, we usually put a tine through to crack the soils open. With no clay content, our soils will not crack on their own.”

Varietal choice also plays a key role. This year, Mike is growing DK Expansion, LG Ambassador, 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.”

Matt agrees: “Effective 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, Mike uses a starter fertiliser, recommends good soil to seed contact and notes that early weed control is preferable.

“In 2020 we did a pre-emergence application of clomazone to clear up various weeds such as hedge mustard and cleavers. 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.”

It’s one advantage of the Clearfield Technology, as Matt explains: “Cleravo lets you wait to see whether the OSR comes through and then clear weeds in a single application. It’s highly effective against volunteer cereals, broad-leaved weeds as well as brassica weeds like charlock and volunteer OSR.

“Newer varieties are performing very well in breeder and AHDB’s recommended list trials,” he adds.