LG Avenger CSFB resilience helps Lincs farmer return to OSR

Cabbage stem flea beetle has been a big factor behind the decline in oilseed rape area over recent years, but one Lincolnshire grower is using varietal resilience to return to the crop after a three-year break.

David Bristow, Lincolnshire

David Bristow of the 650 ha Stourton Estate on the edge of the Lincolnshire Wolds, stopped growing oilseed rape in 2022/23, after several seasons spent battling flea beetle, but decided to give it another go after hearing about the CSFB resilience characteristics of LG Avenger (see panel).

“When our seed supplier United Oilseeds told us about the resilience characteristics, it was one of the main reasons we were prepared to give oilseed rape another go,” says Mr Bristow. “But, it’s not the only reason. LG Avenger really has got the whole package; it’s a well balanced, good variety, that we’ve had no issues with growing so far.”

Rapid establishment

This season, Mr Bristow has 52 ha of LG Avenger in the ground, sown after winter barley in the last week of August. Stubbles were cultivated with a low disturbance subsoiler before drilling with the farm’s Horsch Avatar at 2.6 kg/ha, alongside a companion crop of buckwheat (5 kg/ha) and a surface dressing of 150 kg/ha of DAP fertiliser.

“We did have to wait until there was some moisture before drilling, but once it went in, the LG Avenger was up and away really quickly. The drill worked really well, with very even seed depth, which resulted in excellent establishment.

“The crop grew past the cotyledon stage so rapidly, I don’t think we saw any of the classic shot-holing last autumn, although pressure was generally fairly low.”

Larval assessments in 10 stem samples collected this spring support this, with just one larvae per stem found. “They were all very small, so I suspect they were laid fairly late in the season,” he notes.

The lack of CSFB damage comes despite no insecticides being used on the farm for the past six years, with a large area now signed up to the SFI no insecticide option (CIPM4).

Marginal gains

Mr Bristow is well aware that CSFB remains a threat to oilseed rape, so is keen to do all he can to mitigate the risks when coming back into the crop. Below are some of the steps he has taken:

• Selecting a CSFB resilient variety, LG Avenger
• Waiting for adequate moisture before drilling to aid rapid establishment
• Sowing with a companion crop to ‘mine’ soil phosphate and help disguise the OSR
• Applying DAP fertiliser at drilling to boost establishment
• Leaving taller stubble in the preceding barley crop to lessen the brown soil colour that CSFB are more attracted to
• Focus on achieving uniform seed depth and even emergence
• Applying an early spring multi-nutrient (polysulphate) fertiliser and nitrogen in mid-February to boost spring growth
• Two spring fungicides applied at mid-stem extension and mid-flowering, plus micronutrients at the earlier timing
• Close monitoring of pest and disease levels in-season, and potential CSFB migration risks to next year’s crop

“Individually, they’re all quite small things, but together they do all add up to make a bigger difference,” says Mr Bristow.

Added insurance

LG Avenger’s strong disease scores and pod shatter resistance provide another layer of insurance for protecting yield potential, Mr Bristow says.

“This season we’ve only applied two fungicides in the spring, and nothing last autumn, as the combination of LG Avenger’s phoma resistance and our careful disease monitoring was enough. Crops just never reached the threshold for treatment.”

The crop’s first spring fungicide was based on 200g/ha of tebuconazole, which Mr Bristow says helps to encourage compensatory growth lower down the plant. “It’s not about managing crop height, it’s to encourage crops to branch out more.”

LG Avenger’s pod shatter resistance is another trait Mr Bristow values, especially as the tractor and trailed sprayer used for pre-harvest desiccation lack the ground clearance of self-propelled machines. “Given the pod shatter resistance, we probably won’t use a pod sticker this season.”

Mr Bristow concludes; “The crop’s looked really strong throughout this season so far, with lots of pods forming during flowering, so if it carries all of those through to harvest, I hope it will do very well. We’d like to get at least 4-4.5 t/ha, maybe more ideally.

“I’m confident that we’ll be growing LG Avenger again next season, with a slightly larger area of 59 ha planned.”

LG Avenger

• High yielding hybrid with CSFB resilience characteristics
• High oil content (46.5%)
• Pod shatter resistance
• Turnip Yellows Virus resistance
• Strong disease package, including a light leaf spot rating of 7 and sclerotinia tolerance

CSFB Resilience explained

Florentina Petrescu, Oilseed Rape Product Manager

LG CSFB Resilience is “a novel genetic approach that tackles CSFB at key crop stages, as part of an effective integrated pest management strategy on farm”, explains Florentina Petrescu, Limagrain UK OSR Product Manager.

Resilient varieties feature a series of characteristics that make them better adapted to escaping damage during two crucial periods in the autumn and spring, so it is not just about a single genetic trait, she says. These characteristics include:

1. Strong autumn dynamic growth to help developing crops escape the early “shot holing” damage caused by adult flea beetles feeding on cotyledons and first leaves, which can result in significant leaf loss and complete crop failure in extreme cases
2. Rapid stem elongation in the spring to improve the plant’s resilience to damage caused by larvae mining into petioles and stems
3. A capacity in some varieties (e.g. LG Avenger) to limit the number of larvae that develop within the stems – the exact reasons for this are still being identified
4. Reduced CSFB larvae damage severity – e.g. stunted, bushy plants.